Browse Topic: Turbochargers

Items (265)
Find
Acoustic Assessment in a Small Displacement Diesel Engine2014-32-01291/30/2026
In the last years, the increasing concern for the environmental issues of IC engines has promoted the development of new strategies capable of reducing both pollutant emissions in atmosphere and noise radiation. Engines can produce different types of noise: 1) aerodynamic noise due to intake and exhaust systems and 2) surface radiated noise. Identification and analysis of noise sources are essential to evaluate the individual contribution (injection, combustion, piston slap, turbocharger, oil pump, valves) to the overall noise with the aim of selecting appropriate control strategies. Previous paper focused on the combustion related noise emission. The research activity aimed at diagnosing and controlling the combustion process via acoustic measurements. The optimal placement of the microphone was selected, where the signal was strongly correlated to the in-cylinder pressure development during the combustion process. Analysis and processing of the sound emission allowed the acoustic contribution of the combustion event to be isolated. Some indices capable of relating the combustion noise radiation back to the combustion development were defined. This paper presents an experimental activity devoted to analyze the entire noise generation process of a small displacement diesel engine. The purpose was to identify the contribution of the different sources (mechanical, combustion, fluid dynamic) to the overall emission. The methodology here proposed analyze the specific signature in the frequency domain of each source. The final objective was to use the microphone signal acquired in a proper selected location, to obtain indications about the effective strategies to achieve noise reduction. The repetitiveness of the measurements was guaranteed by a network encircling the engine. Microphones were placed in different positions and tests were performed in the complete engine operative field. In the paper, the experimental set-up is described, the methodology is presented. Results are then shown and discussed.
Chiatti, Giancarlo, Recco, Erasmo, Chiavola, Ornella, Conforto, Silvia
On the Measurement and Simulation of Flow-Acoustic Sound Propagation in Turbochargers2019-01-14886/5/2019
Most of today’s internal combustion engines are turbocharged by combined radial compressors and turbines for downsizing. This mostly leads to reduced orifice noise of both intake and exhaust systems, but the detailed damping mechanisms remain yet unknown. Intake and exhaust systems are developed with 1D-CFD simulations, but validated acoustic sub-models for turbochargers are not yet available. Therefore the aim of this publication is studying the turbocharger’s silencing capabilities and subsequently develop new acoustic turbocharger models. The acoustic properties of the turbocharger can be well described by transmission loss. In addition to thermodynamic variations, parameter variations with wastegate and VTG systems were also performed. A total of four turbochargers of very different sizes were investigated. Low frequency attenuation is dominated by impedance discontinuities, increasing considerably with mass flow and pressure ratio. High frequency transmission loss is generated by destructive interferences in the stator, which depend on the stator mass flow distribution and the turbocharger size. A new generic turbocharger model was developed to model both low frequency impedance discontinuities and high-frequency interferences by combining a generic geometric housing model with dynamically controlled energy terms and conventional turbocharger maps. The high thermodynamic quality is a necessary prerequisite for the high acoustic accuracy achieved. The model could be validated and the accuracy was increased by as much as 5 dB, especially for higher frequencies of engine noise.
Ruppert, Hendrik, Falke, Felix, Pischinger, Stefan, Günther, Marco, Stienen, Ralf
Prediction of Broadband Noise in an Automotive Centrifugal Compressor with Three-Dimensional Computational Fluid Dynamics Detached Eddy Simulations2019-01-14876/5/2019
Centrifugal compressors for automotive turbochargers must operate over wide speed and flow ranges to provide the required air pressure and mass flow rate to the intake manifold of the internal combustion engines. At a fixed rotational speed, the flow field near the inducer of the impeller becomes increasingly unstable with decreasing flow rate, as the incidence angle grows between the air flow approaching the impeller, relative to the tangent of the main impeller blades at the leading edge. Flow field measurements conducted earlier have revealed that once the incidence angle exceeds a critical value (nearly independent of rotational speed) of approximately 15°, reversed flow near the periphery (blade tips) starts penetrating upstream of the impeller, with a high tangential velocity in the direction of impeller rotation. As the incidence angle is increased towards this critical value, whoosh noise elevates, where it remains high for a significant portion of the mid-flow operating range, before decreasing at further elevated incidence angles. To understand this phenomenon further, a detailed, three-dimensional (3D) computational fluid dynamics (CFD) model of the experimental setup was constructed, and simulations were completed at four flow rates along a constant rotational speed. Predictions from this 3D CFD model agree reasonably well with experiments, including the steady-state performance, time-averaged flow field, and noise as captured from the pressure transducer installed in the compressor inlet duct. Near the peak whoosh noise of the studied speed, the impeller flow field was closely examined. Predictions reveal the highest total sound pressure level in the whoosh frequency range occurs near the inducer plane, within the shear layer between the concentric, bi-directional flow structure, with forward flow closer to the axis and reversed flow around the periphery.
Dehner, Rick, Selamet, Ahmet
New Psychoacoustic Criteria for Turbocharger Aero Noise2019-01-14896/5/2019
With ever more stringent regulations related to air pollution and CO2 emissions, there is a growing trend to address this through the downsizing of automotive engines. Turbochargers are used to improve engine power by using exhaust gas energy to provide boosted air pressure for better efficiency. They are a key element in powertrains of today and in the future. During real operating conditions, the rotational speed of a turbo varies greatly making this rotating machinery run in “continuous transient” phases and produces unwanted noises as a result. Recently, we identified a new source of aero noise while developing a new type of turbocharger. Our typical in-house procedure for characterizing usual aero broad band noise source was to use the 3-microphone methodology for measuring the acoustic intensity. However, this methodology is not well adapted if the noise source is tonal, not constant over time and includes high frequency content, which is the case with the new type of turbocharger design and which could create bad noise perception in case of noise transfer into the vehicle cabin. As a result and first step, a set of new psychoacoustic criteria was studied to better understand the relationship between the turbocharger design and the noise content characteristics in addition to the existing methodology. Two new metrics called « Fluctuation Standard Deviation Ratio » and « Low Frequency Peak Emergence » were developed to fulfill this need. The “Fluctuation Standard Deviation Ratio” is assessed in the time domain and can be connected to the human perception of a «steam locomotive», which for a usual compressor flow noise can lead to connotations such as “feeling of unsafety”. The low frequency peak emergence is assessed in the frequency domain and relates to a perception of an annoying whistling sound, which is easily captured by human ears when the peak frequency is below 2 kHz - 3 kHz. Both criteria will be detailed in this paper. Their relevance with human perception will also be shown using practical examples.
Rigault, Alexandre, Kihm, Fred, Baron, Nicolas
Surge Prediction in a Single Sequential Turbocharger (SST) Compressor Using Computational Fluid Dynamics2019-01-14906/5/2019
The Single Sequential Turbocharger (SST) used in Ford’s 6.7L Scorpion Diesel is analyzed using Computational Fluid Dynamics (CFD) to draw conclusions about the compressor stability at low mass flows. The SST compressor concept consists of a double-sided wheel which flows in parallel fed by two separate inlets (front and rear), followed by a single vane-less diffuser, and a volute. CFD simulations for the full stage are performed at low mass flow rates Both, front and rear, sides have ported shroud casing-treatment (CT) in the inlet region. An objective of the analysis is to determine which side of the SST unit compressor (front or rear on the double-sided wheel) suffers flow break down first as the mass flow is reduced, and its impact on the overall stability of the SST compressor. Another objective is to better understand the interactions between the compressor inlet flow and the flow through the casing-treatment. It has been observed that these interactions reduce the effectiveness of the front ported shroud casing-treatment in the selected geometry. This leads to a breakdown of the flow field in the front wheel first and a subsequent overall system instability occurring at higher mass flows compared to a case where the rear wheel flow breaks down first. If the design is such that the rear compressor stalls first, then the SST compressor stage can remain stable to lower mass flow rates. The early instability (at higher mass flow rate) of the compressor due to surge in the front wheel is causing NVH and drivability issues in the vehicle. The utility of CFD to guide the design of the inlets and casing treatment for such type of stages has been demonstrated through comparisons of predicted results to test data.
Karim, Ahsanul, Wade, Robert, Morelli, Anthony, Miazgowicz, Keith, Lizotte, Brian
Agglomeration and Nucleation of Non-Volatile Particles in a Particle Grouping Exhaust Pipe of a Euro VI Heavy-Duty Diesel Engine2019-01-00441/15/2019
The possibility of non-volatile particle agglomeration in engine exhaust was experimentally examined in a Euro VI heavy duty engine using a variable cross section agglomeration pipe, insulated and double walled for minimal thermophoresis. The agglomeration pipe was located between the turbocharger and the exhaust treatment devices. Sampling was made across the pipe and along the centre-line of the agglomeration pipe. The performance of the agglomeration pipe was compared with an equivalent insulated straight pipe. The non-volatile total particle number and size distribution were investigated. Particle number measurements were conducted according to the guidelines from the Particle Measurement Programme. The Engine was fuelled with commercially available low sulphur S10 diesel. Experiments conducted in heavy duty engine relevant operating points were done to sweep the effect of (i) Mass flow rate in the exhaust (ii) Temperature in the exhaust and (iii) Engine speed and thus exhaust pressure pulsation frequencies in the exhaust. The test matrix included eleven operating points at steady-state. The results show that, using the agglomeration pipe, neither significant non-volatile particle reduction nor noticeable change in particle size distribution could be proven. In the current study, nucleation of non-volatile particles could not be observed along the straight pipe. Furthermore, it was found that the variable cross-section agglomeration pipe and straight pipe showed similar results in the total particle number and particle size distribution with respect to non-volatile particles.
K, Arun Prasath, Stenlaas, Ola, Bernemyr, Hanna, Erlandsson, Anders
FSI - MRF Coupling Approach For Faster Turbocharger 3D Simulation2019-01-00071/15/2019
Fluid-Structure Interaction (FSI) simulation approach can be used to simulate a turbocharger. However, this predictive 3D simulation encounters the challenge of a long computational time. The impeller speed can be above 100,000 rpm, and generally a CFD solver limits the maximum movement of the impeller surface per time step. The maximum movement must be a fraction (~0.3) of the cell length, thus the time step will be very small. A Multiple Reference Frame (MRF) approach can reduce computational time by eliminating the need to regenerate the mesh at each time-step to accommodate the moving geometry. A static local reference zone encompassing the impeller is created and the impact of the impeller movement is modeled via a momentum source. However, the MRF approach is not a predictive simulation because the impeller speed must be given by the User. A new simulation approach was introduced that coupled the FSI and MRF approach. Like in the FSI approach, the total moment of the impeller was calculated based on the resultant force acting over the impeller surface. This calculation was conducted for each time-step and the resulted moment was returned back to the solver to update the MRF zone moment. With this coupling approach, the computational time is similar to the MRF approach while maintaining similar accuracy to the FSI predictive approach. The coupling approach was applied to simulate a turbocharger of 15 L diesel engine. The work done by the turbine on the compressor was adjusted to match the impeller speed with the test data. The calculated pressure upstream from the turbine showed a good agreement with test data. The new approach was also used to guide the design of the exhaust manifold for better turbocharger performance.
Abidin, Zainal, Morris, Andrew, Miwa, Jason, Sadique, Jasim, Wang, Yunliang
Cadillac pulls the wraps off two new V-Series sedans19AUTP08_191/1/2019
Cadillac has added two more sedans to its V-Series performance lineup, the 2020 CT4-V and CT5-V. The CT4-V will square off against established C-segment players such as the BMW 3-Series and Mercedes-Benz C-Class, along with Hyundai's new Genesis G70. The CT5-V will compete with the BMW 5-Series and Audi A6. The two new 4-door sedans join the larger 2019 CT6-V sedan in the V-Series stable, though the company noted that the series is evolving to be less focused on hard-core, track-worthy machines, and more about sporty and comfortable daily drivers. “We are inviting even more customers into the V-Series family,” said Brandon Vivian, Cadillac executive chief engineer, “by adding a new level of elevated performance between our Sport models and the ultimate, high-performance track capability that the V-Series has grown to represent.”
Seredynski, Paul
Porsche reveals eighth-generation of fabled 91119AUTP01_151/1/2019
Regularly updating and evolving the Porsche 911's aesthetic signature might seem an impossible task. But more than half a century after its birth, the unveiling of the eighth-generation at the 2018 L.A. Auto Show demonstrated that it is in fact still a totally possible art-with design boss Michael Mauer the chief artist. Designated in-house as the 992 series and slightly larger than the outgoing 991, it is launched in rear-wheel-drive and all-wheel-drive forms-Carrera S and Carrera 4S-and now only in the wide-body width previously used for the Carrera 4 GT3 and GTS, instead of two body widths. Across the nose, the new 911 is 45 mm (1.8 in) wider than the outgoing version, a figure some 911 purists may look at askance, as growth in recent years has already been considerable.
Birch, Stuart
WHAT WE'RE DRIVING18AUTP10_0510/1/2018
Mercedes-Benz is fond of saying it cascades at least some of the S-Class' posh luxury and technology throughout its range. That's just what it has done for the fourth-generation A-Class, the nameplate that sits at the bottom of the brand's lineup. The new A-Class is heaped with cabin tech, in particular. Built on Mercedes' MFA2 front-wheel-drive platform, the A200 AMG Line version driven is well-connected, having the MBUX (Mercedes-Benz User Experience) touchscreen interface (and a touchpad), plus “Hey Mercedes” voice recognition.
Effect of Mesh Size in Numerical Simulation of Turbine Housing in Turbocharger2018-01-17159/10/2018
Numerical method is popular in analyzing turbine housing in turbocharger with an early and rapid risk assessment. However, complex casting and extreme thermal loading from exhaust gas temperature and flow variation under engine duty cycle lead to big thermal stress and this makes material serviced in the plastic zone. Previous numerical simulations show that a mesh size is insensitive to the elastic finite element analysis (FEA), but might not be proper for elastic-plastic FEA, even that other boundary conditions keep same, which indicating simulation results are changeable with mesh size and a simple numerical mesh size convergence might not be enough to guarantee accurate numerical results as well. Therefore, several different mesh sizes are used in elastic-plastic analysis of turbine housing to investigate the influence on numerical results. Based on the numerical results and their comparison, we conclude that theoretical results exist under smaller finite element size but it is impractical to reach under elastic-plastics analysis in engineering application because industrial resource is not enough to support. The reasonable mesh size is recommended to consider both accuracy of simulation results and industrial resource. The fatigue life model and Goodman diagram should be calibrated as well based on this mesh size to evaluate turbine housing design risk.
Guo, Henry, Long, Haiyang
Development of a New 1.8L Down-Speeding Turbocharged Gasoline Engine with Miller Cycle2018-01-17129/10/2018
Upcoming China 4th stage of fuel consumption regulation and China 6a emission legislation require improvement of many existing engines. This paper summarizes an upgrade of combustion system and mechanical layout for a four-cylinder engine family. Based on an existing production process for a naturally aspirated 2.0-liter gasoline engine, a 1.8-liter down-speeded and turbocharged gasoline engine is derived. Starting development by analysis of engine base geometry, a layout for a Miller-Cycle gas exchange with early closing of intake valves is chosen. Requirements on turbocharger configuration are investigated with one-dimensional gas exchange simulation and combustion process will be analyzed by means of 3D-CFD simulation. Challenging boundary conditions of a very moderate long-stroke layout with a stroke/bore-ratio of only 1.037 in combination with a cost efficient port fuel injection system and fixed valve lift profiles are considered. To compensate reduced in-cylinder charge motion of small valve lift three measures are taken. Firstly, the intake port is modified for significantly increased tumble motion at higher valve lift. This is combined with a masking of the intake valve area in the combustion chamber and enables a high turbulence even at very small valve lift. Finally, the valve lift profile is optimized by changing cylinder head layout from tappet valve train to roller-finger follower. This has also positive impact on friction behavior. Further reduction of parasitic losses by reduced main bearing diameter, adapted piston ring layout and introduction of an oil pump with two pressure stages accompanies the increase of combustion efficiency. The development targets with almost ninety-two percent of the maximum torque achieved at an engine speed 1250 rpm and a minimum specific fuel consumption of 230 g/kWh are reached, which means maximum thermal efficiency of 36.8% normalizing to caloric value of 42.5 MJ/kg.
Ye, Yisu, Xu, Libing, Wang, Jinshi, Yao, Kefu, Zhao, Mingxiang, Dieterich, Carsten, Souren, Mike, Morcinkowski, Bastian
Effective Suppression of Surge Instabilities in Turbocharger Compression Systems through a Close-Coupled Compressor Inlet Restriction2018-01-17149/10/2018
The current work demonstrates effective suppression of compression system surge instabilities by installing a variable cross-sectional flow area restriction within the inlet duct of a turbocharger centrifugal compressor operating on a bench-top facility. This restriction couples with the compressor, similar to stages in a multi-stage turbomachine, where the effective pressure ratio is the product of those for the restriction and compressor. During experiments at constant compressor rotational speed, the compressor is stable over the negatively sloped portion of the pressure ratio vs. flow rate characteristics, so the restriction is eliminated within this operating region to preserve compressor performance. At low flow rates, the slope of the compressor alone characteristics reaches a positive value, and the unrestricted compression system enters mild surge. Further reduction of flow rate with the unrestricted compressor inlet results in a sudden transition to deep surge instabilities. Within this low-flow operating range, where surge instabilities occur in the compressor-alone system, the restriction is activated to modify the slope of the combined (restriction plus compressor) characteristics and stabilize the system. An analytical approach is presented to illustrate the impact of compressor inlet restriction on the stability of the combined restriction-compressor system. Over the tested rotational speed range, experimental results demonstrate that a compressor inlet restriction of less than 3 kPa is capable of suppressing surge instabilities and extending the low-flow compressor operating range to approximately one-third of the mass flow rate where deep surge occurred without compressor inlet restriction.
Dehner, Rick, Selamet, Ahmet, Miazgowicz, Keith
Adaptive Turbo Matching: Radial Turbine Design Optimization through 1D Engine Simulations with Meanline Model in-the-Loop2018-01-09744/3/2018
Turbocharging has become the favored approach for downsizing internal combustion engines to reduce fuel consumption and CO2 emissions, without sacrificing performance. Matching a turbocharger to an engine requires a balance of various design variables in order to meet the desired performance. Once an initial selection of potential compressor and turbine options is made, corresponding performance maps are evaluated in 1D engine cycle simulations to down-select the best combination. This is the conventional matching procedure used in industry and is ‘passive’ since it relies on measured maps, thus only existing designs may be evaluated. In other words, turbine characteristics cannot be changed during matching so as to explore the effect of design adjustments. Instead, this paper presents an ‘adaptive’ matching methodology for the turbocharger turbine. By coupling an engine cycle simulation to a turbine meanline model (‘in-the-loop’), adjustments in turbine geometry are reflected in both the exhaust boundary conditions and overall engine performance. Running the coupled engine-turbine model within an optimization framework, the optimal turbine design evolves. The methodology is applied to a Renault 1.2 L turbocharged gasoline engine, to minimize fuel consumption over given full- and part-load operating points, while meeting performance constraints. Despite the current series production turbine being a very good match already, and with optimization restricted to a few turbine geometric parameters, the full-load case predicted a significant cycle-averaged BSFC reduction of 3.5 g/kWh, while the part-load optimized design improved BSFC by 0.9 g/kWh. No engine design parameters were changed, so further efficiency gains would be possible through simultaneous engine-turbocharger optimization. The proposed methodology is not only useful for improving existing designs; it can also develop a bespoke turbine geometry in new engine projects where there is no previously available match. For these reasons, ‘adaptive’ turbo matching will become the standard approach in the automotive industry.
Kapoor, Prakhar, Costall, Aaron W., Sakellaridis, Nikolaos, Hooijer, Jochem, Lammers, Rogier, Tartoussi, Hadi, Guilain, Stéphane
Steady-State Experimental and Meanline Study of an Asymmetric Twin-Scroll Turbine at Full and Unequal and Partial Admission Conditions2018-01-09714/3/2018
The use of twin-scroll turbocharger turbines has gained popularity in recent years. The main reason is its capability of isolating and preserving pulsating exhaust flow from engine cylinders of adjacent firing order, hence enabling more efficient pulse turbocharging. Asymmetrical twin-scroll turbines have been used to realize high pressure exhaust gas recirculation (EGR) using only one scroll while designing the other scroll for optimal scavenging. This research is based on a production asymmetrical turbocharger turbine designed for a heavy duty truck engine of Daimler AG. Even though there are number of studies on symmetrical twin entry scroll performance, a comprehensive modeling tool for asymmetrical twin-scroll turbines is yet to be found. This is particularly true for a meanline model, which is often used during the turbine preliminary design stage. This study presents the development of a generalized meanline model for a twin-scroll turbine, which can be used in the early design stages, concentrating on asymmetrical scrolls. The improvements from the previous meanline model, i.e., the inlet duct and interspace model, in order to enable asymmetrical scroll prediction is described. The latter is based on the popular theory of turbomachinery wakes mixing, adopted from literature. The model is validated against experimental cold gas stand data under equal and unequal-admission conditions. Comparison between the model and experiments indicates the importance of the inlet duct and interspace model between the scrolls in obtaining satisfactory predictions across different admission conditions, due to the non-symmetrical features between the scrolls.
Palenschat, Torsten, Mueller, Markus, Rajoo, Srithar, Chiong, Meng Soon, Newton, Peter, Martinez-Botas, Ricardo, Tan, Feng Xian
The Development of a New V6 3.5L Turbocharged Gasoline Engine2018-01-03664/3/2018
For the launch of the redesigned Lexus LS, a new 3.5 L V6 twin turbo engine has been developed aiming at unparalleled performance on four axes, “driving pleasure”, “power-performance”, “quietness” and “fuel economy”. To achieve outstanding power-performance and high thermal efficiency, the specifications have been optimized for high speed combustion. The maximum torque of 600 Nm, power of 310 kW (yielding specific power of 90 kW/L), and the maximum thermal efficiency of 37% have been achieved using several new technologies including a high efficiency turbocharger. A prototype vehicle equipped with this engine and Direct-Shift 10AT achieved a 0-60 mph acceleration time of 4.6 sec, with extremely good CAFE combined fuel economy of 23 mpg and power-performance aligned with V8 turbocharged offerings from competing OEM’s.
Yamazaki, Daichi, Mori, Akio, Murase, Eiji
Numerical and Experimental Investigation of Effect of Tongue Shape on Turbine Reliability2018-01-04834/3/2018
Turbine housing in turbocharger is a critical part which must withstand severe cyclic mechanical and thermal load throughout its service life. The combination of thermal transients with mechanical load cycles results in a complex evolution of damage, leading to thermal mechanical fatigue (TMF) of the material and, after a certain number of loading cycles, to failure of the component. The volute tongue at radial turbine housing is a key feature which is frequently the first location subject to thermal crack failure due to turbine design. Design of tongue is of importance to improve system's TMF performance. In this work, two tongues including square and elliptic shape on radial turbine fatigue are studied. TMF performance is evaluated by finite element analysis (FEA). In particular, experimental method is carried out in order to validate the simulation model. The good agreement is found between numerical and experimental results. Based on both numerical and experimental investigation we identify and in particular quantify the influence of tongue shape which can raise the design quality of turbine housing in the preliminary design stage.
Guo, Henry, Jia, Wenchuan, Li, Na
Ultra-High Fuel Injection Pressure with Massive EGR to Enable Simultaneous Reduction of Soot and NOx Emissions2018-01-02274/3/2018
In this study both double and triple injection strategies were used with fuel pressures up to 300 and 250 MPa, respectively. Tests were conducted at medium load conditions with cooled, high-pressure EGR at a ratio of 40% and higher. A four-cylinder production engine, featuring double turbochargers with one variable geometry turbocharger, was tested. The double injection strategy consisted of a 20% close-coupled pilot injection while the triple injection strategy introduced a post injection consisting of 10% the total cycle fuel. Results of this study do not indicate an advantage to extreme fuel pressure. The increased air entrainment reduces soot while increasing the premixed burn heat release, mean cylinder temperature, and NOx. Compared to the double injection scheme, triple injections achieved much lower soot for the same EGR rate with only a small NOx penalty. Under the conditions tested, triple injections could be used with high EGR as a mixing strategy, allowing for the use of fuel pressures below 200 MPa to achieve a low FSN that can be effectively cleaned by the DPF.
Ogren, Ryan M., Kong, Song-Charng
Diesel Engine Cylinder Deactivation for Improved System Performance over Transient Real-World Drive Cycles2018-01-08804/3/2018
Effective control of exhaust emissions from modern diesel engines requires the use of aftertreatment systems. Elevated aftertreatment component temperatures are required for engine-out emissions reductions to acceptable tailpipe limits. Maintaining elevated aftertreatment components temperatures is particularly problematic during prolonged low speed, low load operation of the engine (i.e. idle, creep, stop and go traffic), on account of low engine-outlet temperatures during these operating conditions. Conventional techniques to achieve elevated aftertreatment component temperatures include delayed fuel injections and over-squeezing the turbocharger, both of which result in a significant fuel consumption penalty. Cylinder deactivation (CDA) has been studied as a candidate strategy to maintain favorable aftertreatment temperatures, in a fuel efficient manner, via reduced airflow through the engine. This work focuses on prediction and demonstration of fuel economy benefits of CDA when implemented at idle and low load portions of the emission certification cycles, such as the heavy duty federal test procedure (HD-FTP), and other real-world drive cycles, including the Orange County bus and port drayage creep cycles. A 3.4% benefit in fuel economy has been demonstrated over the HD-FTP, while maintaining tailpipe-out NOx emissions. Greater improvements in fuel economy have been predicted over the real world cycles, with a 5.6% reduction predicted over the Orange County bus cycle and 35% reduction predicted over the port drayage creep cycle.
Joshi, Mrunal, Gosala, Dheeraj, Allen, Cody, Srinivasan, Sirish, Ramesh, Aswin, VanVoorhis, Matthew, Taylor, Alexander, Vos, Kalen, Shaver, Gregory, McCarthy Jr, James, Farrell, Lisa, Koeberlein, Edward D.
Divided Exhaust Period Implementation in a Light-Duty Turbocharged Dual-Fuel RCCI Engine for Improved Fuel Economy and Aftertreatment Thermal Management: A Simulation Study2018-01-02564/3/2018
Although turbocharging can extend the high load limit of low temperature combustion (LTC) strategies such as reactivity controlled compression ignition (RCCI), the low exhaust enthalpy prevalent in these strategies necessitates the use of high exhaust pressures for improving turbocharger efficiency, causing high pumping losses and poor fuel economy. To mitigate these pumping losses, the divided exhaust period (DEP) concept is proposed. In this concept, the exhaust gas is directed to two separate manifolds: the blowdown manifold which is connected to the turbocharger and the scavenging manifold that bypasses the turbocharger. By separately actuating the exhaust valves using variable valve actuation, the exhaust flow is split between two manifolds, thereby reducing the overall engine backpressure and lowering pumping losses. In this paper, results from zero-dimensional and one-dimensional simulations of a multicylinder RCCI light-duty engine equipped with DEP are presented. It is shown that while DEP helped reduce pumping penalty at medium and high loads, the pumping benefit was negated by crankshaft power consumption from a mechanical supercharger which made up for the boost deficit as the low exhaust enthalpy could not be efficiently utilized by a fixed geometry turbocharger (FGT). However, by replacing the FGT with a variable geometry turbocharger (VGT), a 1% improvement in brake-specific fuel consumption (BSFC) over the stock engine configuration was observed at high load, as the VGT allowed more efficient exhaust energy utilization through aspect ratio adjustment. In addition, by closing the blowdown valve at low load, higher exhaust gas temperatures were obtained by bypassing the turbocharger and thereby eliminating exhaust heat losses, which would be useful for aftertreatment thermal management.
Bharath, Anand Nageswaran, Reitz, Rolf, Rutland, Christopher
Virtual Full Engine Development: 3D-CFD Simulations of Turbocharged Engines under Transient Load Conditions2018-01-01704/3/2018
The simulation of transient engine behavior has gained importance mainly due to stringent emission limits, measured under real driving conditions and the concurrently demanded vehicle performance. This is especially true for turbocharged engines, as the coupling of the combustion engine and the turbocharger forms a complex system in which the components influence each other remarkably causing, for example, the well-known turbo lag. Because of this strong interaction, during a transient load case, the components should not be analyzed separately since they mutually determine their boundary conditions. Three-dimensional computational fluid dynamics (3D-CFD) simulations of full engines in stationary operating points have become practicable several years ago and will remain a valuable tool in virtual engine development; however, the next logical step is to extend this approach into the transient domain. This article evaluates the potential of different turbocharger models being included in 3D-CFD engine models, starting from a map-based approach ranging up to a fully discretized 3D-CFD turbocharger. The approach presented in this article combines a three-dimensional representation of the entire engine, including the turbine and compressor housing, but replacing the turbocharger rotors with performance maps. Several numeric investigations were conducted to reduce calculation time and improve the system stability. A virtual hot gas test bench is set up in three different simulation environments to compare the map-based turbocharger against a conventional zero-dimensional (0D)/one-dimensional (1D) modeling and a 3D-CFD turbine. The analysis focuses on differences in stationary behavior and the response to pressure pulses. The modeling approach, validated on the virtual hot gas test bench, is used to model a two-cylinder engine. It is analyzed under stationary load conditions showing the interaction between turbocharger and engine within a working cycle. In a second step, transient load conditions over multiple working cycles are applied to the engine model, and the results are compared to the respective measurements obtained at the test bench.
Kaechele, Andreas, Chiodi, Marco, Bargende, Michael
Divided-Exhaust Turbocharger System with Boost-Valve2018-01-08954/3/2018
In a divided-exhaust turbocharging system, 1 exhaust valve and port from each cylinder can be directed to the turbocharger turbine (referred to as the Blowdown Path) and the other can bypass the turbocharger (referred to as the Scavenge Path). The Blowdown and Scavenge valve events are determined based on the functions of the blowdown and displacement phases of the exhaust process. In our previous publications of another version of Divided Exhaust Period Turbocharging, the Valve Event Modulated Boost system (VEMB), we demonstrated significant engine efficiency and performance improvements over the base turbocharged engine. Reductions in pumping work and high-load Residual Gas Fraction are the primary reasons for efficiency and performance improvements. In this project we have evaluated through simulation and engine testing, the further advantages of the Divided-Exhaust-Boost (DEB) system version of Divided Exhaust Boosting; a version that does not require a concentric-camshaft for boost control. This system retains the previously-reported very large improvement in catalyst light-off performance, which is to be expected from a system that can completely remove the turbocharger from the exhaust pathway during the cold-start period.
Roth, David B., Chen, Wei, Ciaravino, Joseph
Testing and Implementation of a Turbocharged Formula SAE Vehicle2018-01-09674/3/2018
Research on turbocharging for FSAE at the University of Malta, has been ongoing for a number of years. 1D simulations were done to determine best design configuration and determine a lowered compression ratio. A decompression plate was installed on the Kawasaki 600 cc engine. Calibration of the engine was performed on the engine dynamometer. A hot-gas test stand for testing of the turbocharger was developed. The turbocharger speed was measured by a custom built hall-effect sensing setup that is compact enough to be implemented also in the FSAE vehicle. Bespoke camshafts with optimized valve timing determined through WAVE 1D simulations and designed with Valdyn® were machined. The turbocharged setup was used on the University of Malta FSAE vehicle in the FSAE Italy 2017 competition. Knock was investigated through in-cylinder pressure measurements and use of commercial knock sensor on the 600 cc engine. Benchmarking in-cylinder pressure measurement tests were carried out on a 1.4 liter naturally aspirated Ford engine for both ‘masked’ and ‘unmasked’ in-cylinder pressure sensors to assess the possibility and effect of cavity resonance in such experimental tests. High speed data acquisition was performed at 200 kHz per channel and was post-processed using LabVIEW®. Calibration of the knock detection feature on the programmable ECU required the determination of the relevant parameters namely: knock frequency, reference and knock windows and knock to reference window amplitude ratio. Calibration of the ECU knock parameters was aided by playing back recorded engine sensor data to minimize the time of engine knocking.
Azzopardi, Jean Paul, Farrugia, Jean-Paul, Caruana, Carl, Grech, Nicholas, Farrugia, Nicholas, Chircop, Marlon, Farrugia, Mario, Farrugia, Michael
Experimental Investigation on Surge Phenomena in an Automotive Turbocharger Compressor2018-01-09764/3/2018
Downsizing and turbocharging are today considered an effective way to reduce CO2 emissions in automotive gasoline engines, especially for the European and US markets. In the broad field of research and development for engine boosting systems, the instability phenomenon of surge has gathered considerable interest in recent years, as the main limiting factor to high performance boosting and boost pressure control. To this extent, developing an in-depth knowledge of the surge dynamics and on the phenomena governing the transition from stable to unstable operation can provide very valuable information for the design of the intake system and boost pressure control algorithms, allowing optimal boost pressure without compromising the transient response. This paper describes an experimental study that aims at better understanding the phenomena leading to the inception of surge, and exploring the effects of the downstream circuit geometry on the compressor dynamic behavior in surge and prior to surge. A specific circuit adaptable in volume and length was designed to study the effect of different configurations on the steady flow compressor performance, with special reference to the surge line position. Instantaneous static pressures are measured in several locations upstream and downstream the compressor. Besides, dynamic sensors to measure noise and vibrations are also adopted. The preliminary results of the experimental campaign are presented, exploring the influence of geometry variations on the compressor map and surge dynamics.
Marelli, Silvia, Misley, Anna, Silviestri, Paolo, Capobianco, Massimo, Taylor, Alexandra, Canova, Marcello
Drivecycle Benefits of Controlling Airflow with the SuperTurbo™2018-01-09704/3/2018
The SuperTurbo™ is a driven turbocharger that uses a high-speed traction drive combined with a CVT (Continuously Variable Transmission) or electric motor to provide additional power to or from the turbo shaft. The CVT can be shifted to a ratio that provides a turbo speed that generates a desired boost pressure and air flow rate to the engine. Unlike a conventional turbocharger, where the turbine and compressor powers must be balanced, the a driven turbocharger can provide additional power to the turbo shaft through supercharging when the turbine is not collecting sufficient power to drive the compressor to the desired boost pressure, and during other operating conditions can absorb excess turbine power through turbo-compounding to improve engine efficiency. This direct control of air flow to the engine enables greater flexibility in engine operation. The topics presented focus on heavy-duty diesel engines, but the concepts can be applied to all engine types. Transient response is improved, as well as fuel efficiency during transient operation of diesel engines, as excess fueling to provide exhaust energy to the turbine is avoided. Instead, additional airflow is provided to the engine through supercharging to increase combustion efficiency. This aids in engine downspeeding, as well as downsizing, to provide improved drivability of the vehicle. Simulations and engine testing show that efficient transients can provide a fuel savings of up to 6% over a transient drivecycle, and the ability to downspeed the engine can provide an additional 3% efficiency gain. Overall, the ability to directly control airflow to the engine provides flexibility for engine operation that is not possible with a conventional turbocharger.
Brown, Jared W., Waldron, Thomas
Evaluation of Engine-Related Restrictions for the Global Efficiency by Using a Rankine Cycle-Based Waste Heat Recovery System on Heavy Duty Truck by Means of 1D-Simulation2018-01-14514/3/2018
As a promising concept to improve fuel efficiency of a long-haul heavy duty truck with diesel engine, organic Rankine cycle (ORC) based waste heat recovery system (WHR) by utilizing the exhaust gas from internal combustion engine has continuously drawn attention from industry in recent years. The greatest achievable global efficiency may be, however, restricted by the engine. On one hand, engine operating conditions have direct impact on the temperature and the mass flow of exhaust gas, which is the waste heat source, on the other hand, the engine cooling system limits the heat rejection from the condenser of the WHR system. This paper aims to evaluate the impacts of the varied engine applications considering the effects of the WHR system on the global efficiency and engine emissions. A complex 0D/1D-simulation model for a turbocharged production heavy duty engine with low-/high-temperature cooling circuit and a WHR system with ethanol as working fluid have been established in GT-Suite. The WHR-System recovers the heat from high pressure exhaust gas recirculation as well as exhaust gas after turbocharger. The parametric studies have revealed the engine-related restrictions for the global efficiency at WHR-System design operating point. A comparison between one- und two-stage turbochargers in respect of the recovered exergy and an investigation of different integration positions for the WHR-system with respect to the heat rejection potential have been carried out. This paper differs from the most current researches on ORC based WHR-System by the fact that it focuses on the engine performance changes regarding the integration of WHR system rather than the control and optimization of WHR system for a fixed engine configuration.
Yang, Kangyi, Bargende, Michael, Grill, Michael
Thermodynamic and Practical Benefits of Waste Energy Recovery Using an Electric Turbo-Generator Under Different Boosting Methods2018-01-08514/3/2018
This paper provides insight into the tradeoffs between exhaust energy recovery and increased pumping losses from the flow restriction of the electric turbo-generator (eTG) assessed using thermodynamic principles and with a detailed GT-Power engine model. The GT-Power engine model with a positive displacement expander model was used to predict the influence of back pressure on in-cylinder residuals and combustion. The eTG is assessed for two boosting arrangements: a conventional turbocharger (TC) and an electrically assisted variable speed (EAVS) supercharger (SC). Both a low pressure (post-turbine) and high pressure (pre-turbine) eTG are considered for the turbocharged configuration. The reduction in fuel consumption (FC) possible over various drive cycles is estimated based on the steady-state efficiency of frequently visited operating points assuming all recovered energy can be reused at an engine efficiency of 30% with 10% losses in the electrical path. On the city FTP and US06 cycles, the EAVS SC engine benefits more than the turbocharged from adding the eTG. The opposite is observed for the highway cycle where adding the eTG causes greater fuel consumption reductions for the turbocharged engine. Boost reserve in the TC case at low load, however, makes the EAVS SC with eTG (boost-by-wire) a better boosting and energy recovery system overall with reductions in FC up to 1.4%, 2.4% and 4.6% relative to the TC engine over the FTP, highway and US06 cycles respectively.
Kiwan, Rani, Middleton, Robert, Stefanopoulou, Anna
Turbocharger Impact on Diesel Electric Powertrain Performance2018-01-09654/3/2018
When electrifying the powertrain, there arises an opportunity to revise the traditional turbocharging trade-off between fuel-economy and transient performance. With the help of electrification, it might be possible to make the trade-off in favor of fuel economy, since transient response can be improved by the electric machine. The paper investigates this trade-off by looking at three turbocharger selections. A conventionally dimensioned turbocharger, an efficiency optimized turbocharger with maintained flow capacity, and an efficiency optimized turbocharger with increased flow capacity. The concepts are evaluated on the following cases: stationary operation, engine tip-in performance, vehicle acceleration performance, and on road fuel economy performance. The investigation is based on a validated mean value engine model of a six cylinder inline CI engine, and on a validated driveline and vehicle model of a heavy-duty truck. The evaluations are made with the help of simulations and numerical optimal control. The results show that there is a fuel saving potential, and that the transient response is improved by the electric machine.
Leek, Alf Erik Viktor, Eriksson, Lars
Use of Water-Butanol Blends in a Turbocharged Common Rail Dual Fuel Engine for Enhanced Performance and Reduce Smoke Levels2018-01-02514/3/2018
Experiments were conducted on a turbocharged three cylinder automotive common rail diesel engine with port injection of butanol. This dual fuel engine was run with neat butanol and blends of water and butanol (up to 20% water by mass). Experiments were performed at a constant speed of 1800 rpm and a brake mean effective pressure of 11.8 bar (full load) at varying butanol to diesel energy share values while diesel was either injected as a single pulse or as twin pulses (Main plus Post). Open engine controllers were used for varying the injection parameters of diesel and butanol. Water butanol blends improved the brake thermal efficiency by a small extent because of better combustion phasing as compared to butanol without water. When the butanol to diesel energy share was high, auto-ignition of butanol occurred before the injection of diesel. This lowered the ignition delay of diesel and hence elevated the smoke level. Two separated heat release phases along with high rates of pressure rise were thus observed. This limited the maximum butanol to diesel energy share. However, it was also possible to enhance the butanol to diesel energy share from about 28 to 33% through the use of water butanol blends. However, the change in the amount of water in the blend had little impact due to its small quantity. Increase in the amount of butanol decreased the NO emission because of reduced charge temperature. However, the water in the blend had little impact due to its small quantity. Smoke and NO emissions were lower with the water butanol blends. Use of Main plus Post Injection with the blend (W10) was effective in reducing NO (by 10%) and smoke (by 52%) emissions, without any adverse effect on brake thermal efficiency. The optimal main to post offset was 10 deg. CA and the best post quantity was about 10% of the total diesel injected.
Yadav, Jaykumar, Ramesh, A
The Effect of Swirl on the Flow Uniformity in Automotive Exhaust Catalysts2017-01-238410/8/2017
In aftertreatment system design, flow uniformity is of paramount importance as it affects aftertreatment device conversion efficiency and durability. The major trend of downsizing engines using turbochargers means the effect of the turbine residual swirl on the flow needs to be considered. In this paper, this effect has been investigated experimentally and numerically. A swirling flow rig with a moving-block swirl generator was used to generate swirling flow in a sudden expansion diffuser with a wash-coated diesel oxidation catalyst (DOC) downstream. Hot-wire anemometry (HWA) was used to measure the axial and tangential velocities of the swirling flow upstream of the diffuser expansion and the axial velocity downstream the monolith. With no swirl, the flow in the catalyst monolith is highly non-uniform with maximum velocities near the diffuser axis. At high swirl levels, the flow is also highly nonuniform with the highest velocities near the diffuser wall. An intermediate swirl level exists where the flow is most uniform. To gain further insight into the mechanisms controlling flow redistribution, numerical simulations have been performed using the commercial CFD code STARCCM+. With no swirl, the central jet transverses the diffuser, and a drastic flow redistribution takes place near the monolith face due to its high resistance. Immediately downstream of the sudden expansion, the flow separates from the diffuser wall forming a separation zone around the central jet. Increasing swirl reduces the size of this separation zone, and eventually leads to the formation of the central recirculation zone characteristic of high swirl flows. At intermediate swirl levels, the size of the wall separation zone is reduced considerably, while the axial adverse pressure gradient is insufficient to cause a central recirculation. Such a flow regime occurs at relatively low swirl levels (S ~ 0.23). This may have positive implications for aftertreatment system design with low residual swirl levels from the turbine, which might be tuned by adjusting the distance between the turbine and the catalyst or employing guide vanes. The findings can be directly transferred to other aftertreatment systems with a catalyst or particulate filter. Moreover, swirling flows with an obstruction or a high resistance device downstream (e.g. a heat exchanger or filter) are present in many other applications such as cooling flows, combustion and turbomachinery. Therefore the results are relevant to a much wider research and industrial community.
Rusli, Ijhar H., Aleksandrova, Svetlana, Medina, Humberto, Benjamin, Stephen F.
Unsteady Performance Simulation Analysis of a Waste-Gated Turbocharger Turbine under Different Valve Opening Conditions2017-01-241710/8/2017
An electronic waste-gated turbocharger for automotive application can accurately control the boost pressure and effectively reduce turbo-lag. It can improve the transient responsive performance of engine and the acceleration performance of vehicle, which makes vehicle have a better adaptation to the complex traffic environment. A detailed analysis of aerodynamic working principle of electronic wastegate is the foundation for designing the control strategy of electronic wastegate. Putting turbine with electronic wastegate under unsteady condition that simulates the pulse exhaust gas of engine and studying influences of different valve opening on the performance of turbine has the practical value. This paper sets fixed and periodical unsteady conditions and adopts numerical methods to explore the performance of turbine in twin-entry turbocharger and the flow loss of bypass. Steady simulation structure is given for reference. The influence and change rule of wastegate valve opening on turbine performance are researched comprehensively. The results show that the nearer the valve opening approximates to full close, the greater the influence on the turbine unsteady performance is, and the bigger the flow loss in per degree is. The flow loss in the turbine and the bypass are evaluated to reveal the mechanism of influence on turbine performance of valve opening and flow loss. This paper is helpful to optimize the structure of electronic actuator and design the control strategy.
Fan, Houchuan, Ni, Jimin, Shi, Xiuyong, Jiang, Nan, Qu, Dayong, Zheng, Yi, Zheng, Yinghong
Simulation and Test Research for Integrated Exhaust Manifold and Hot End Durability2017-01-243210/8/2017
In order to reduce emissions, size and manufacturing cost, integrated exhaust manifold become popular in gasoline engine, especially in three-cylinder engine. Moreover, due to shorter length, lighter weight, and less component connections, the exhaust manifold and hot end durability will improve apparently. In this work, an advanced cylinder head with integrated exhaust manifold is adopted in a three-cylinder turbo engine. Because of this integration characteristic, the gas retain in cylinder head longer and the temperature reach higher level than normal cylinder head, which will cause thermal fatigue failure more easily. To validate the exhaust manifold and hot end durability, series simulation and test validation work have been done. Firstly, overall steady state and transient temperature simulation was done for global model. For turbocharger, in order to simulate the outlet turbulent flow and 3d rotation, a code was compiled to define this 3d rotation. In this code, the inlet boundary was defined by turbine blade’s rotational velocity, direction and angle. Secondly, based on temperature prediction, thermal modal, high cycle fatigue (HCF) and thermal mechanical fatigue (TMF) analysis were done in sequence. According to HCF analysis, catalyst bracket fatigue factors fulfilled the require limit. According to TMF analysis, cylinder head life which contains the exhaust manifold fulfilled the life cycle target. Temperature and vibration test were done on rig test, good correlation is shown between test and simulation results. Finally, no crack failure was found inside the cylinder head and hot end after durability test, which also proved the TMF and HCF results indirectly.
Li, Xiangwang, Wang, Weimin, Zou, Xiongcai, Zhang, Zhiming, Zhang, Wenlong, Zhang, Shemin, Chen, Tao, Cao, Yuhuang, Chen, Yuanda
Development of New I3 1.0L Turbocharged DI Gasoline Engine2017-01-242410/8/2017
In recent years, more attentions have been paid to stringent legislations on fuel consumption and emissions. Turbocharged downsized gasoline direct injection (DI) engines are playing an increasing important role in OEM’s powertrain strategies and engine product portfolio. Dongfeng Motor (DFM) has developed a new 1.0 liter 3-cylinder Turbocharged gasoline DI (TGDI) engine (hereinafter referred to as C10TD) to meet the requirements of China 4th stage fuel consumption regulations and the China 6 emission standards. In this paper, the concept of the C10TD engine is explained to meet the powerful performance (torque 190Nm/1500-4500rpm and power 95kW/5500rpm), excellent part-load BSFC and NVH targets to ensure the drivers could enjoy the powerful output in quiet and comfortable environment without concerns about the fuel cost and pollution. The combustion system with side-mounted 6-hole direct injector and 200bar injection pressure has been optimized by CFD simulation and optical engine investigation. To ensure performance output and transient responsiveness, an efficient and low inertia turbocharger was selected. Effective technical measures including friction reducing, thermal management, variable oil pump and Dual VVT were applied in order to achieve the good fuel economy. Special attentions have been paid to the engine structure design, mass balancing strategy and mounting system optimization to achieve excellent NVH performance which is at same level similar to a 4-cylinder TGDI gasoline engine. Benefited from the modular design concept, the engine size was minimized, which has the advantage for packaging, especially for hybrid vehicles. Through the development work, the engine performance and BSFC targets have been achieved and confirmed by engine and vehicle tests. This engine has been installed in one of the passenger cars (1205 to 1320kg) and 18% fuel consumption reduction has been achieved in the NEDC cycle compared to 1.6L NA engine while maintaining fun-to-drive and NVH performance
Zhang, Shemin, Li, Huaping, Chen, Tao, Jiang, Nan, Tan, Xinzhen, Deng, Limei, Xia, Qingsong, Kapus, Paul, Ma, Mingtang, Li, Wei, Zhang, Junqiang, Ma, Qingjun, Xia, Yong
Study on Nonlinear Rotordynamics Characteristics for Electric Compound Turbocharger2017-01-241810/8/2017
The electric compound turbocharger(ECT) which integrates a high speed motor into a turbocharger rotor shaft can be used transiently to accelerate the turbocharger more quickly in response to an acceleration requirement. It can utilize the exhaust gas energy fully to improve the engine fuel efficiency and benefit for engine with lower emissions. The key technique of ECT is to solve the reliability problems when an electrical motor is integrated into a turbocharger shaft between the turbine and compressor wheels will increase the burden for the bearing support and affect the turbocharger shaft rotation characteristics. In order to know the dynamics behavior of higher load bearing system is explored for reliability, this paper focus on the nonlinear rotor dynamics characteristics of ECT rotor bearing system. Based on the principle and structure of ECT rotor bearing system, the basic theory method and dynamics model of rotor bearing system is established considered the nonlinear fluid film force. The shaft critical speed, unbalance response, stability performance are analyzed, the nonlinear film whirl and the film oscillation analysis show a complex rotor dynamic behavior of ECT. The influence on the key structural parameters and film clearance for rotor bearing system are discussed. The nonlinear rotor vibration characteristics of electric compound turbocharger under actual operating conditions are predicted. The results can support a theoretical basis for the design of nonlinear shafting dynamics of ECT and increase rotor bearing system reliability for future products.
Zhang, Hong, Wang, Zhuo, Hong, Zhouzhensen
Improvement of Diagnosing Methods of the Diesel Engine Functioning under Operating Conditions2017-01-221810/8/2017
Operability and efficiency of transport diesel engines significantly depend on periodical diagnosis of its technical condition. The article considers the features of monitoring and diagnostic of transport diesel engines with the help of vibroacoustic analysis of high pressure fuel equipment and gas distribution mechanism. Functional scheme of diagnostic system and analytical method of TDC determination is described. Article gives an example of four-stroke and two-stroke diesel engines diagnosis. Also the article shows turbocharger speed determination and diagnosis with the help of vibroacoustic spectrum analysis. The main feature of the given methods is their high efficiency for diagnosis of transport diesel engines during operation.
Varbanets, Roman, Karianskyi, Sergey, Rudenko, Sergey, Gritsuk, Igor V., Yeryganov, Aleksey, Kyrylash, Olena, Aleksandrovskaya, Nadezhda
Engine Oil Components Effects on Turbocharger Protection and the Relevance of the TEOST 33C Test for Gasoline Turbocharger Deposit Protection2017-01-234110/8/2017
Countries from every region in the world have set aggressive fuel economy targets to reduce greenhouse gas emissions. To meet these requirements, automakers are using combinations of technologies throughout the vehicle drivetrain to improve efficiency. One of the most efficient types of gasoline engine technologies is the turbocharged gasoline direct injection (TGDI) engine. The market share of TGDI engines within North America and globally has been steadily increasing since 2008. TGDI engines can operate at higher temperature and under higher loads. As a result, original equipment manufacturers (OEMs) have introduced additional engine tests to regional and OEM engine oil specifications to ensure performance of TGDI engines is maintained. One such engine test, the General Motors turbocharger coking (GMTC) test (originally referred to as the GM Turbo Charger Deposit Test), evaluates the potential of engine oil to protect turbochargers from deposit build-up. In this paper, the authors discuss the impact of typical engine oil components on GMTC performance. Concern about turbocharger deposits is not a new phenomenon, however. In the early 1990s the TEOST 33C bench test was developed to simulate turbocharger coking, and early studies showed a correlation between TEOST 33C results and field issues. A comparison of the TEOST 33C bench test and the GMTC engine test revealed no such correlation between the two tests under the conditions studied. Due to this lack of correlation, a comparison of TEOST 33C response with turbocharger deposits generated during field operation was performed.
Yang, Kongsheng, Fletcher, Kristin A., Styer, Jeremy P., Lam, William Y., Guinther, Gregory H.
A Comparison of On-Engine Surge Detection Algorithms using Knock Accelerometers2017-01-242010/8/2017
On-engine surge detection could help in reducing the safety margin towards surge, thus allowing higher boost pressures and ultimately low-end torque. In this paper, experimental data from a truck turbocharger compressor mounted on the engine is investigated. A short period of compressor surge is provoked through a sudden, large drop in engine load. The compressor housing is equipped with knock accelerometers. Different signal treatments are evaluated for their suitability with respect to on-engine surge detection: the signal root mean square, the power spectral density in the surge frequency band, the recently proposed Hurst exponent, and a closely related concept optimized to detect changes in the underlying scaling behavior of the signal. For validation purposes, a judgement by the test cell operator by visual observation of the air filter vibrations and audible noises, as well as inlet temperature increase, are also used to diagnose surge. The four signal treatments are compared with respect to their reliability as surge indicator and the time delay between surge onset and indication. Results show that the signal power in the surge frequency band has reasonably good properties as surge indicator. The normal Hurst exponent is problematic, since periodic vibrations from engine firing dominate the scaling behavior. Root mean square and the above mentioned scaling exponent do not measure vibrations caused by surge directly, but rather the reduction in housing vibrations due to the engine load drop. Nevertheless, it was found to be possible to design an indicator that gives good results based on the change in scaling behavior.
Kerres, Bertrand, Cronhjort, Andreas, Mihaescu, Mihai, Stenlaas, Ola
NVH Performance Improvement of a Turbo-Charged GDI Engine based on the Simulation and Experiment Studies2017-01-242610/8/2017
In recent years, Turbo-charged GDI technology is more and more widely used, which can meet the high demand of the engine performance and efficiency, but the resulting reliability and NVH issues also need to be paid attention to [1]. Traditional NVH performance improvement is mostly based on the experience design and repeatable test, which lead to longer development period, high cost, and also ineffective results. NVH performance simulations play more important role in engine vibration and noise prediction along with the development of the simulation technology[2][3]. The force response analysis is usually used to evaluate the NVH performance of the engine structure under the standard excitation. However, dynamic analysis of the crank train, valve train, and piston can be carried out based on the AVL software family, also the vibration and airborne noise of whole engine can be predicted directly at different speed and load [4]. The NVH performance of a turbo-charged GDI engine was studied based on the simulation and experiment in this paper. Firstly the engine NVH targets including the airborne noise, mount vibration and so on are set up, and the targets are broken down into system and component if possible. Secondly, the mechanism dynamics, engine vibration and noise simulations were carried out, and the weaknesses of the original engine design had been found out. Some appropriate structural improvements to the main parts and new NVH performance prediction were done according to the targets of NVH performance. Then experiment results show that simulation method of radiation noise OA level prediction is basically correct, and a series of structural improvement measures are very effective. Some special problems such as the turbocharger noise were also investigated, and some remarkable effects have been achieved.
Zhang, Zhiming, Wang, Weimin, Wang, Jiangtao, Zhang, Jiming, Chen, Yuanda, Zhang, Wenlong, Yang, Guofang, Fan, Fugui, Zhang, Wenxiang, Huang, Fengqin, Li, Xiangwang
The Development of Acoustics Compressor Maps and Computational Aeroacoustic Method to Evaluate Turbocharger Inlet Flow Control Devices2017-01-20719/19/2017
The advent of turbochargers and the Eco-Boost technology at Ford in gasoline engines creates new challenges that need to be addressed with innovative designs. One of them is flow induced noise caused by airflow entering the turbocharger during off design operation. At certain vehicle operation conditions, the mass flow rate and pressure ratio are such that compressor wheel can generate a wide range of acoustic frequencies. Characterization of ‘whistles’ or pure tonal noises, ‘whoosh’ or broad band frequency noise caused by flow separation from the blade surfaces, and chirps, where the frequency increases or decreases with time are a few of the common error states. Understanding the fundamental mechanisms of such noise generation is necessary for developing effective countermeasures for the noise source generation. Computational Aero-Acoustic (CAA) analyses are performed to study the effects of inlet and outlet conditions to find the source of the noise. These analyses are carried out with three-dimensional (3D) Computational Fluid Dynamics (CFD) models including the rotating compressor wheel, inlet duct geometry, volute, diffuser, and exit duct geometry. Geometric changes to the turbocharger inlet are developed and their effects on both the performance and acoustic signature of the turbocharger are studied. After CFD and CAA studies, the turbocharger inlet geometry modifications are tested on a turbocharger gas stand. The test stand is instrumented to acquire time resolved pressure fluctuations that are post processed into acoustic data. The acoustic data is overlaid on a standard compressor map. The development of the new acoustic compressor map identifies the areas in the performance region where noise sources of various frequencies are prevalent.
Miazgowicz, Keith
Assessment of Combustion Mechanical Noise Separation Techniques on a V8 Engine2017-01-18466/5/2017
The noise radiated by an ICE engine results from a mixture of various complex sources such as combustion, injection, piston slap, turbocharger, etc. Some of these have been categorized as combustion related noise and others as mechanical noise. Of great concern is the assessment of combustion noise which, under some operating conditions, is likely to predominate over the other sources of noise. The residual noise, produced by various other sources, is commonly referred to as mechanical noise. Being able to extract combustion and mechanical noise is of prime interest in the development phase of the engine and also for diagnostic purposes. This paper presents the application of combustion mechanical noise separation techniques on a V8 engine. Three techniques, namely the multi regression analysis, the classical Wiener filter and the cyclostationary (synchronous) Wiener filter, have been investigated. The techniques have been applied to microphone recordings measured at one meter distance from an engine running on a test bench. Reference in-cylinder pressure sensors have been instrumented and synchronously acquired together with the microphones. Strengths and weaknesses of the techniques are assessed and presented in the paper. Finally a source separation technique is applied as a pre-processing step to the sound recordings measured on a microphone array. Sound source localization then allows to localize and quantify the combustion and mechanical sources of noise on the engine. This is illustrated with an application example.
Bianciardi, Fabio, Janssens, Karl, Gryllias, Konstantinos, Delvecchio, Simone, Manna, Claudio
The Effect of Ported Shroud Recirculating Casing Treatment on Turbocharger Centrifugal Compressor Acoustics2017-01-17966/5/2017
Ported shroud compressor covers recirculate low momentum air near the inducer blade tips, and the use of these devices has traditionally been confined to extending the low-flow operating region at elevated rotational speeds for compressors on compression-ignition (CI) engines. Implementation of ported shrouds on compressors for spark-ignition (SI) engines has been generally avoided due to operation at pressure ratios below the region where ported shrouds improve low-flow range, the slight efficiency penalty, and the perception of increased noise. The present study provides an experimental investigation of performance and acoustics for a SI engine turbocharger compressor both with a ported shroud and without (baseline). The objective of implementing the ported shroud was to reduce mid-flow range broadband whoosh noise of the baseline compressor over 4-12 kHz. At the compressor inlet, elevated BPF noise of the ported shroud partially offset the mid-flow range (4-12 kHz) whoosh noise suppression and the maximum overall SPL reduction was 6 dB(A), while elevated 4-12 kHz and BPF noise caused an SPL increase of up to 5 dB(A) at low speed and flow. Since the ported shroud did not significantly increase low-flow 4-12 kHz noise at the compressor outlet, overall SPL was reduced over the mid to low flow range by a maximum of 12 dB(A).
Dehner, Rick D., Selamet, Ahmet, Steiger, Michael, Miazgowicz, Keith, Karim, Ahsanul
Fast 2-D Heat Transfer Model for Computing Internal Temperatures in Automotive Turbochargers2017-01-05133/28/2017
The growing concerns about emissions in internal combustion engines, makes necessary a good prediction of the after-treatment inlet temperature in fast one-dimensional engine simulation codes. Different simple models have been developed during the last years which improve the prediction of the turbocharger heat transfer phenomena. Although these models produce good results when computing the turbine outlet temperature, those models focus on the axial heat transfer paths and lack the capability of producing detailed results about the internal thermal behavior of the turbocharger. In this work, a new version of heat transfer model for automotive turbochargers is presented. This model discretizes the turbocharger in both the radial and axial directions, and computes the heat transfer and temperature at different parts of the machine. Aiming for a low computational cost, it was designed to be compatible with fast one-dimensional engine simulations as a replacement of previous models [1]. The paper deals with the description of the radial heat transfer model, tuning and validation for not water cooled turbocharger. The paper describes the heat transfer equations that serve as base for modeling other turbochargers by modifying geometry, material, and boundary conditions with the advantage of computing the oil temperature inside the turbocharger central housing, lubrication channels, and maximum level of temperature at different points in the bearing system, with the aim of reduce experimental tasks. The model results can be use practically to study heat exchanges occurring inside and the effects on the turbocharger performance. It will allow to evaluate thermal damage done to the system itself, guidance for researchers on the development of effective procedures and tools to cope with the technological exigencies in the optimum performance of the turbocharging system. As well as influences on the working fluid temperatures which leads oil coke formation, that can affect the performance of the engine[2].
Serrano, Jose, García-Cuevas lng, Luis Miguel, Tiseira, Andres, Rodriguez Usaquen, Tatiana, Mijotte, Guillaume
Exhaust System Thermal Management: A Process to Optimize Exhaust Enthalpy for Cold Start Emissions Reduction2017-01-01413/28/2017
Future vehicle North American emissions standards (e.g., North American Tier 3 Bin 30 or LEVIII SULEV 30) require the exhaust catalyst to be greater than 80% efficient by 20 seconds after the engine has been started in the Federal Test Procedure. Turbocharged engines are especially challenged to deliver fast catalyst light-off since the presence of the turbocharger in the exhaust flow path significantly increases exhaust system heat losses. A solution to delivering cost effective SULEV 30 emissions in turbocharged engines is to achieve fast catalyst light-off by reducing exhaust system heat losses in cold start, without increasing catalyst thermal degradation during high load operation. A CAE methodology to assess the thermal performance of exhaust system hardware options, from the exhaust port to the catalyst brick face is described, which enables compliance with future emissions regulations. In addition to close-coupling of the catalyst, wastegate strategies, directed wastegate flow, engine displacement, and scroll configuration were studied with respect to the magnitude and preservation of exhaust enthalpy delivered to the catalyst face. The concept of total sensible enthalpy available at the catalyst face, and a measure of exhaust thermal efficiency is introduced as a means of quantifying the likelihood of successful catalyst light-off prior to vehicle drive-away. Boundary condition definition, numerical requirements, and correlation to measured data are discussed.
Host, Ray, Moilanen, Peter, Fried, Marcus, Bogi, Bhageerath
Potentials of Electrical Assist and Variable Geometry Turbocharging System for Heavy-Duty Diesel Engine Downsizing2017-01-10353/28/2017
Diesel engine downsizing aimed at reducing fuel consumption while meeting stringent exhaust emissions regulations is currently in high demand. The boost system architecture plays an essential role in providing adequate air flow rate for diesel fuel combustion while avoiding impaired transient response of the downsized engine. Electric Turbocharger Assist (ETA) technology integrates an electric motor/generator with the turbocharger to provide electrical power to assist compressor work or to electrically recover excess turbine power. Additionally, a variable geometry turbine (VGT) is able to bring an extra degree of freedom for the boost system optimization. The electrically-assisted turbocharger, coupled with VGT, provides an illuminating opportunity to increase the diesel engine power density and enhance the downsized engine transient response. This paper assesses the potential benefits of the electrically-assisted turbocharger with VGT to enable heavy-duty diesel engine downsizing. A 1D engine simulation model of the Caterpillar 7.1L 6-cylinder diesel engine has been developed and validated against engine test data taken with ETA device fitted. Both steady state and transient engine performance are evaluated with different electric power levels, motor response time and VGT vane positions. The ETA technology gives transient response benefits over a range of transient events, but with diminishing returns at the higher levels of ETA power. Better transient response and fuel consumption could be achieved by combining ETA device with VGT versus a standard fixed turbine. The importance of ETA control with fast response time during transient maneuver is highlighted. This study also demonstrates the engine speed drop is less significantly affected than recovery time over block load test by employing ETA technology. This potential limit of the requirement to have sufficient initial excess boost for downsized engine could be addressed by controlling the VGT vane position. Finally, the capability of this optimized boosting system to enable downsizing from 9.3L to 7.1L is demonstrated.
Xue, Xingyu, Rutledge, John
Heat Transfer Effect on Performance Map of a Turbocharger Turbine for Automotive Application2017-01-10363/28/2017
In the last few years, the effect of diabatic test conditions on compressor performance maps has been widely investigated leading some Authors to propose different correction models. The aim of the paper is to investigate the effect of heat transfer phenomena on the experimental definition of turbocharger maps, focusing on turbine performance. An experimental investigation on a small turbocharger for automotive application has been carried out and presented. The study focused onto the effects of internal heat transfer on turbine thermomechanical efficiency. The experimental campaign was developed considering the effect of different heat transfer state by varying turbine inlet temperature, oil and coolant temperature and compressor inlet pressure. An original model previously developed by the Authors is adopted for the correction of compressor steady flow maps. The major benefit of this method is represented by the easiness of data post-processing, the data base economy, the reduced number of geometrical and physical input parameters required and the accuracy of the solution. Besides, this model does not need an out-of-standard test bench to obtain the compressor maps. The corrected compressor results were then used to evaluate turbine thermomechanical efficiency, generally assessed on the basis of compressor power absorption.
Marelli, Silvia, Gandolfi, Simone, Capobianco, Massimo
Study on the Interaction of Clearance Flow and Shock Wave in a Turbine Nozzle2017-01-10393/28/2017
Radial flow Variable Nozzle Turbine (VNT) enables better matching between the turbocharger and engine. At partial loading or low-end engine operating points, the nozzle vane opening of the VNT is decreased to achieve higher turbine efficiency and transient response, which is a benefit for engine fuel consumption and emission. However, under certain small nozzle opening conditions (such as nozzle brake and low-end operating points), strong shock waves and strong nozzle clearance flow are generated. Consequently, strong rotor-stator interaction between turbine nozzle and impeller is the key factor of the impeller high cycle fatigue and failure. In present paper, flow visualization experiment is carried out on a linear turbine nozzle. The turbine nozzle is designed to have single-sided clearance, and the Schlieren visualization method is used to describe the formation and development process of clearance flow and shock wave under different clearance and expansion ratio configurations. Numerical simulations are also performed to investigate the flow structure and the interaction behavior between shock wave and clearance flow in details. Results indicate that for the investigated turbine nozzle, the shock wave is squeezed and bent in the opposite direction of the main flow in the interaction region. In the location close to the end-wall, the shock wave is truncated by the clearance flow and mixed downstream-wise with a distorted shock wave structure. Furthermore, increasing the clearance size causes the distortion of the shock wave structure near the end-wall, while the shock wave intensity near mid-span is increased. Meanwhile, the clearance leakage flow and shock wave can cause the static pressure of the nozzle vane exit to fluctuate violently.
Lei, Xinguo, Qi, Mingxu, Sun, Harold, Shi, Xin, Hu, Liangjun
Experimental and Numerical Study of the Water Injection to Improve the Fuel Economy of a Small Size Turbocharged SI Engine2017-01-05403/28/2017
In this work, a promising technique, consisting of a liquid Water Injection (WI) at the intake ports, is investigated to overcome over-fueling and delayed combustions typical of downsized boosted engines, operating at high loads. In a first stage, experimental tests are carried out in a spark-ignition twin-cylinder turbocharged engine at a fixed rotational speed and medium-high loads. In particular, a spark timing and a water-to-fuel ratio sweep are both specified, to analyze the WI capability in increasing the knock-limited spark advance. In a second stage, the considered engine is schematized in a 1D framework. The model, developed in the GT-Power™ environment, includes user defined procedures for the description of combustion and knock phenomena. Computed results are compared with collected data for all the considered operating conditions, in terms of average performance parameters, in-cylinder pressure cycles, burn rate profiles, and knock propensity, as well. Finally, the validated model is applied to investigate the full potential of water injection in reducing the knock tendency and improving the fuel economy in a wide load range. The numerical results highlight that WI technique involves significant Brake Specific Fuel Consumption (BSFC) advantages, especially at the medium-high loads. These benefits are limited by the maximum allowable levels for the in-cylinder pressure, while additional advantages are obtained in terms of reduced turbine inlet temperature, turbocharger speed, and boost pressure. The developed numerical procedure, based on validated combustion and knock sub-models, is able to take into account the complex interactions among different parameters, which affect the engine behavior. It is hence believed to realistically forecast the WI-related BSFC advantages and constraints, induced by thermo-mechanical stresses. Simultaneously, it underlines the need of a partial engine redesign to fully exploit WI potential.
De Bellis, Vincenzo, Bozza, Fabio, Teodosio, Luigi, Valentino, Gerardo
Dynamic Downsizing Gasoline Demonstrator2017-01-06463/28/2017
Gasoline engine downsizing is already established as a technology for reducing vehicle CO2 emissions. Further benefits are possible through more aggressive downsizing, however, the tradeoff between the CO2 reduction achieved and vehicle drivability limits the level of engine downsizing currently adopted by vehicle manufacturers. This paper will present the latest results achieved from a very heavily downsized engine, and resulting demonstrator vehicle, featuring eSupercharging in combination with a conventional turbocharger. The original 1.2 litre, 3-cylinder, MAHLE downsizing engine has been re-configured to enable a specific power output in excess of 160 kW/litre. Of key importance is a cost effective, efficient and flexible boosting system. The Aeristech eSupercharger, operating at 48 V, enables the transient response and low speed torque to be more than recovered, enabling both very high specific output and specific torque characteristic with excellent transient response and drive-ability characteristics, clearly demonstrating eSupercharging as a key technology for enabling further engine downsizing. The resulting heavily downsized engine has been installed into a demonstrator vehicle that also features an advanced 48 V lead-carbon battery pack and a 48 V belt-driven integrated starter generator (BISG). The battery and BISG have been selected to enable the continuous high-output (6 kW) operation of the eSupercharger to support prolonged operation of the engine at low speed and high-torque output. The fuel consumption of the resulting demonstrator vehicle has been analysed over a number of drive-cycles and the benefits of the downsized engine in conjunction with the complete mild-hybrid system have been assessed.
Bassett, Michael, Hall, Jonathan, Cains, Tony, Underwood, Mark, Wall, Richard, Richards, Bryn GR
Optimal Pressure Based Detection of Compressor Instabilities Using the Hurst Exponent2017-01-10403/28/2017
The compressor surge line of automotive turbochargers can limit the low-end torque of an engine. In order to determine how close the compressor operates to its surge limit, the Hurst exponent of the pressure signal has recently been proposed as a criterion. The Hurst exponent quantifies the fractal properties of a time series and its long-term memory. This paper evaluates the outcome of applying Hurst exponent based criterion on time-resolved pressure signals, measured simultaneously at different locations in the compression system. Experiments were performed using a truck-sized turbocharger on a cold gas stand at the University of Cincinnati. The pressure sensors were flush-mounted at different circumferential positions at the inlet of the compressor, in the diffuser and volute, as well as downstream of the compressor. Results show that the previously identified threshold value distinguishing between surge and stable operation when the analysis was carried out for a different and smaller compressor can be used also for this much larger compressor. The investigation concerning the sensor locations reveals that pressure sensors at the outlet or shortly upstream the volute tongue give the clearest distinction between fully stable operation and operation close to the surge line. Further investigations show that as currently implemented, the criterion would need a minimum sampling duration of 500 ms and sampling frequency of 512 Hz. An extended algorithm based on distinguishing between a mono- and multifractal pressure signal is shown to have potential as an early warning indicator.
Kerres, Bertrand, Mihaescu, Mihai, Gancedo, Matthieu, Gutmark, Ephraim
Automated Calibration for Compressor Recirculation Valve Control2017-01-05943/28/2017
Turbocharger compressors are susceptible to surge – the instability phenomena that impose limitations on the operation of turbocharged engines because of undesired noise, engine torque capability constraints, and hardware strain. Turbocharged engines are typically equipped with a binary compressor recirculation valve (CRV) whose primary function is to prevent compressor surge. Calibration of the associated control strategy requires in-vehicle tests and usually employs subjective criteria. This work aims to reduce the calibration effort for the strategy by developing a test procedure and data processing algorithms. An automated calibration for CRV control is developed that will generate a baseline calibration that avoids surge events. The effort to obtain the baseline calibration, which can be further fine-tuned, is thereby significantly reduced. Procedures are developed for testing and analysis that combines a previously developed surge characterization method with unconstrained nonlinear optimization. An adaptive algorithm is also presented that can update the CRV control calibration online. The developed procedures are demonstrated on vehicle data and compared with manually obtained calibrations.
Xiao, Baitao, Hellstrom, Erik, Wang, Yan, Buckland, Julia, Santillo, Mario
Items per page:
1 – 50 of 265