Browse Topic: Exhaust manifolds

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Towards Quantitative Prediction of Urea Thermo-Hydrolysis and Deposits Formation in Exhaust Selective Catalytic Reduction (SCR) Systems2019-01-09924/2/2019
In order to assist in fast design cycle of Diesel engines selective catalytic reduction (SCR) exhaust systems, significant endeavor is currently being made to improve numerical simulation accuracy of urea thermo-hydrolysis. In this article, the achievements of a recently developed urea semi-detailed decomposition chemical scheme are assessed using three available databases from the literature. First, evaporation and thermo-hydrolysis of urea-water solution (UWS) single-droplets hanged on a thin thermocouple ring (127 μm) as well as on a thick quartz (275 μm), have been simulated at ambient temperature conditions ranging from 473K to 773K. It has been shown that the numerical results, in terms of evaporation rate and urea gasification, as well as droplet temperature history are very close to the experiments if the heat flux coming from the droplet support is properly accounted for. Indeed, an additional conduction flux has proved to be necessary in the evaporation model in order to account for the droplet heating coming from the support (i.e. thermocouple ring or quartz bead). This additional heat conduction flux has shown more critical for droplets suspended on a thick quartz. It is also argued that our detailed kinetic mechanism is able to ensure accurate thermal decompositions as long as the temperature inside the droplet is still nearly uniform. This assumption is shown to be true at low temperature and so, at low evaporation and thermo-hydrolysis rates. However, for high gas temperature, bubble nucleation near the support surface induces non-uniform temperature distribution.. This process makes accurate simulation of thermal decomposition extremely dependent on the local temperature inside such large suspended droplets. These results are also relevant and underline the modelling difficulties that we must tackle when it comes to studying the evaporation, boiling and thermolysis of liquid films and deposits on the exhaust walls. Next verification of the models has been carried out using UWS sprays injected in 6-m long pipe under typical Diesel engine exhaust manifold conditions. In this case, good agreement with experiments in terms of urea to ammonia (NH3) conversion efficiencies has been obtained under different temperatures and residence times. In addition, it proved that by-products (like solid biuret, Cyanuric acid and even ammelide) can be formed in the spray parcels upon water evaporation is completed during their travel to the exhaust catalyst inlet. These solid by-product particles may clog the catalyst inlet section.
Habchi, Chaouki, Quan, Shaoping, Drennan, Scott, Bohbot, Julien
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
Achieving Ultra-Low Oil Consumption in Opposed Piston Two-Stroke Engines2019-01-00681/15/2019
The opposed piston two-stroke (OP2S) engine architecture is widely recognized for its improved fuel efficiency relative to a four-stroke engine. Achates Power Inc. seeks to demonstrate the market readiness of the OP2S engine by proving competitive in other important areas, one of which is oil consumption. Achieving oil consumption competitive to modern four-stroke engines is thus a key step in bringing OP2S technology to market. Two-stroke engines have historically suffered from higher engine lube oil consumption and subsequent emissions and durability challenges. This is primarily due to two main features of traditional two-stroke engines; the direct interaction of the piston skirt and rings with the intake and/or exhaust ports, which results in a direct leak path for lube oil to the combustion chamber and/or exhaust manifold, and crankcase-scavenged architectures which entrain oil into air being pumped through the crankcase. The OP2S engine architecture directly addresses these concerns by utilizing intake and exhaust manifolds, a closed crankcase system, and oil control rings which operate outboard of the ports. Previous work has shown the importance of careful consideration of cylinder liner, piston, and ring design in minimizing oil consumption of the OP2S architecture. This work evaluates further refinements in cylinder form, hone texture and oil retention, port sealing ring design, and oil control ring design. A Da Vinci DALOC sulfur-trace analyzer for real-time oil consumption measurement was used to generate speed vs. load maps of oil consumption of an Achates Power OP2S A48 development engine, operated under typical medium-duty conditions. The engine demonstrated oil consumption levels competitive with modern four-stroke benchmarks and completed a 100-hour durability test with no measured performance loss or increase in oil consumption. This work represents a key step towards proving the potential of the Achates Power OP2S engine architecture in the commercial and passenger vehicle markets.
Chown, Dan, Koszewnik, John, MacKenzie, Ryan, Pfeifer, Dan, Callahan, Brian, Vittal, Manny, Froelund, Kent
Preparing BMW Motorrad’s Boxer Engine for the Future: Improving Performance, Driveability and Efficiency While Fulfilling Future Emission Standards2018-32-008310/30/2018
Engine development mostly revolves around the same competing goals. With the implementation of the EU4 and EU5 emission standards for motorcycles, the difficulty of increasing performance and improving driveability and efficiency, while simultaneously fulfilling the Emission standards becomes even higher. Though the automotive industry offers a variety of solutions for the named topics, their implementation in a high performance motorcycle engine with specific needs regarding packaging, a wide operating range and full load behavior, represents a special challenge. This paper presents the approach of BMW Motorrad to meet these goals on the example of the boxer engine, focusing on the methodology throughout the development process. The gas exchange system of the engine was optimized using 1D gas dynamic simulations and 3D CFD analysis for a redesign of the valve train, ports and valves. The results of the calculations were further confirmed by experiments at the flow test bench measuring discharge coefficients and using particle image velocimetry (PIV). Combined simulation and engine testing led to a newly developed exhaust manifold enabling a faster light-off and a more stable operating temperature of the catalyst, while reducing raw exhaust emissions through a new injector layout. Engine experiments showed lower emissions, an improved efficiency and a more stable combustion in part load as well as an increased performance at full load. These results translated into lower exhaust emissions and fuel consumption when testing the motorcycle in the world motorcycle harmonized test cycle (WMTC).
Oppelt, Maximilian, Schwarz, Frank, Eibl, Rüdiger, Gaitan, Pedro
Thermo-Mechanical Fatigue Testing of Welded Tubes for Exhaust Applications2018-01-00904/3/2018
Selected ferritic stainless steel sheets for exhaust applications were tested under thermo-mechanical fatigue (TMF) condition in the temperature range of 400-800 °C with partial constraint. Straight welded tubes were used as the testing coupons to withstand large compression without buckling, and to understand the effect of welding as well. Repeated tests confirmed the observed failure scenario for each material type. The hysteresis loop behaviors were also simulated using the mechanism-based integrated creep and fatigue theory (ICFT) model. Although more development work is needed, for quick material screening purpose this type of testing could be a very cost effective solution for materials and tube weld development for exhaust applications.
Quan, Guangchun, Wu, Xijia, Lafleur, Luc, zhang, Zhong
High-Performance Rear- and Mid-Engine Vehicle Exhaust System Temperatures2018-01-14364/3/2018
Hot surface ignition of combustible material is a known cause of vehicle fires. Although the detailed mechanisms of hot surface ignition are highly complex, the surface temperature is known to play a crucial role in this process. There has been limited previous work in the literature on this topic, much of which has focused on engine or exhaust system surface temperatures of the most common types of passenger vehicles. Also, much of this work was done in an unrepeatable manner and suffered from measurement technique induced errors. The focus of the present work is on repeatable and low measurement technique induced error temperature measurements of exhaust system surface temperatures of rear- and mid-engine sports cars. Temperature measurements were made at several points along the exhaust systems of vehicles both with and without turbo chargers on a 5-mile oval track. The exhaust system surface temperatures were examined under conditions of transient acceleration and steady-state driving for vehicle speeds of up to 125 mph (201 km/h). Finally, the effect of engine rotation speed for a constant vehicle speed on exhaust surface temperature was examined. It was found that the exhaust temperatures of rear- and mid-engine sports cars have maximum surface temperatures that are within the range of temperatures reported in literature for passenger vehicles in the range of speeds for which comparison data exists. It was also found that increased engine rotation speed for a constant vehicle speed results in increased surface temperatures for all measured locations.
Papageorge, Michael, Colwell, Jeff
A Simulative Study for Post Oxidation During Scavenging on Turbo Charged SI Engines2018-01-08534/3/2018
Fulfilling exhaust emissions regulations and meet customer performance needs mainly drive the current engine development. Turbocharging system plays a key role for that. Currently turbocharging should provide highest engine power density at high engine speed by also allowing a very responsive performance at low end. This represents a trade-off in turbocharger development. A large scaled turbine allows having moderate exhaust gas back pressure for peak power region, but leading to loss of torque in low engine speed. In the last years of engine development scavenging helped to get away a bit from this trade-off as it increases the turbine mass flow and also reduces cylinder internal residual gas at low engine speed. The mostly in-use lean strategy runs air fuel ratios of closed to stoichiometric mixture in cylinder and global (pre catalyst) of λ = 1.05 to l = 1.3. This will be out of the narrow air fuel ratio band of λ = 1 to ensure NOx conversion in the 3-way-catalyst. The use of the rich strategy (in cylinder λ < 1, pre catalyst stoichiometric) increases significantly the brake specific fuel consumption and lowers the exhaust gas temperature, which leads to loss of turbine power. Nevertheless as a result of this procedure, fresh air and large amount of unburned fuel enters the catalyst in short sequences. This can lead to high temperature in the catalyst and thus reduces its live cycle. The present paper aims to show the potential of oxidation of unburned species pre turbine to empower the turbine and also reduce the amount of emissions needed to convert by the catalyst. Within this paper the use of detailed reactions kinetics mechanism of CO and H2 will be shown. Furthermore some 3D CFD calculation results will be presented to show the mixture in the exhaust manifold. To show the maximum potential 1D simulation including a strongly reduces oxidation mechanism has been carried out.
Guenther, Torsten, Grill, Michael, Bargende, Michael
Simulation Study of 1D-3D Coupling for Different Exhaust Manifold Geometry on a Turbocharged Gasoline Engine2018-01-01824/3/2018
One-dimensional (1D) simulation tools, the computing speed of which is relatively fast, usually solve simple complexity problems. The solving process of 1D simulation is mostly based on one-dimensional dynamic equations and empirical laws and thus in some cases it cannot obtain a similar accuracy with the time-consuming three-dimensional (3D) simulation tools. The 1D-3D co-simulation, which combines the advantages of the two simulation tools while minimizes the disadvantages, is a method that integrates and runs the two simulation tools concurrently. The coupled simulation can offer a 3D analysis for which a detailed information is needed while offer system level information in the rest of the whole system where averaged results are sufficient. The approach not only minimizes the computational cost, but avoids demand for imposing accurate boundary conditions to the 3D simulation. But nowadays, a lot of paper only use the approach to obtain boundary condition from 1D environment, few study focus on the influence of 3D part on system. (e.g influence of intake or exhaust manifold on flow in cylinder in co-simulation).The objective of this study includes two aspects, one compares the difference between 1D and the 1D/3D coupling, the other studies the influence of the 4-1 and 4-2-1 exhaust manifold on in-cylinder residual fraction gas (RGF) based on the proposed 1D and 3D co-simulation approach. It describes a detailed analysis of the integrated 1D-3D simulation for two different exhaust manifold geometries on a turbocharged gasoline engine. The research results show that the induction process of the original 1D model and the co-simulation model were nearly equal, but the exhaust pressure of the coupled model was smoother than that of the original 1D model. The 4-1 exhaust manifold has a larger residual gas fraction due to the more severe pulse interference and the 4-2-1 exhaust manifold is able to mitigate this phenomenon by separating the runner 1/runner 4 with runner 2/runner 3. Furthermore, by added a spacer plate at exit port of 4-2-1 manifold, it can further reduce in-cylinder RGF and enable more uniformity among four cylinders. Therefore, the 4-2-1 exhaust manifold can be used to enhance the engine performance to achieve the concept of downsizing and down-speeding, and also it can be adopted to optimize the fuel efficiency by advancing the spark timing.
Zhang, Chaolin, Hu, Bo, lai, Chenguang, Zhang, Hailin, Qin, Ling, Leng, Xiaoli, Huang, Wenpeng
Sodium Cooling Efficiency in Hollow Valves for Heavy Duty Engines2018-01-03684/3/2018
As a consequence of the ongoing evolution of engines, where performance is continuously improving and the use of alternative fuels is being adopted by many engine manufacturers, thermal working conditions of the exhaust valves are increasingly critical. In order to better resist the higher temperature levels of the exhaust gases, current development ranges from improvement of the cooling concept for the overall system, new materials for valve set components up to the upgrade of the exhaust manifold material. Change in the design of several valvetrain components due to the increased thermal loads is a logical consequence of this technical evolution process. Hollow exhaust valves filled with Sodium (Na) are a known technology that is widely used in passenger car engines to improve thermal behavior and to avoid the need to change to expensive materials (Ni-base alloys). Nevertheless, shaker-cooling effect of Na for engine speeds below 3.000 [rpm] has been questioned in the past and this technology has not been fully explored in heavy duty (HD) applications [1]. In order to investigate the thermal efficiency or effectiveness and to confirm Na-filled valves as a potential technical solution for thermal issues in HD engines, back-to-back analyses (FEA) and tests (temperature measurements and endurance) were performed, mainly focused on heavy duty spark ignition (SI) engines (gas fueled) and on severe applications of diesel engines.
Zenklusen, Fernando, Coenca, Marcio, Puck, Alexander
Pressure Amplitude Influence on Pulsating Exhaust Flow Energy Utilization2018-01-09724/3/2018
A turbocharged Diesel engine for heavy-duty on-road vehicle applications employs a compact exhaust manifold to satisfy transient torque and packaging requirements. The small exhaust manifold volume increases the unsteadiness of the flow to the turbine. The turbine therefore operates over a wider flow range, which is not optimal as radial turbines have narrow peak efficiency zone. This lower efficiency is compensated to some extent by the higher energy content of the unsteady exhaust flow compared to steady flow conditions. This paper experimentally investigates the relationship between exhaust energy utilization and available energy at the turbine inlet at different degrees of unsteady flow. A special exhaust manifold has been constructed which enables the internal volume of the manifold to be increased. The larger volume reduces the exhaust pulse amplitude and brings the operating condition for the turbine closer to steady-flow. The operating points are defined by engine speed and boost pressure. From these values the isentropic turbine work is calculated and with the measured compressor work the mean turbine efficiency is estimated. The results show that more energy has to be provided to the turbine at larger exhaust manifold volumes to maintain a constant boost pressure, indicating that the efficiency of the turbine decreases.
Holmberg, Ted, Cronhjort, Andreas, Stenlaas, Ola
The NiceC Programming LanguageTBMG-283152/1/2018
NiceC is an improved version of ANSI C. It attempts to clean up C as much as possible using syntax translation. A type checker for NiceC is under development. The NiceC programming language is translated to, and fully compatible with, ordinary C. Thus it can be used as a drop-in replacement for C. The main benefits of using NiceC are as follows:
Experimental Investigation of Cold Start Emission using Dynamic Catalytic Converter with Pre-Catalyst and Hot Air Injector on a Multi Cylinder Spark Ignition Engine2017-01-236710/8/2017
Control of harmful emissions during cold start of the engine has become a challenging task over the years due to the ever increasing stringent emission norms. Positioning the catalytic converter closer to the exhaust manifold is an efficient way of achieving rapid light-off temperature. On the other hand, the resulting higher thermal loading under high-load engine operation may substantially cause thermal degradation and accelerate catalyst ageing. The objective of the present work is to reduce the light-off time of the catalyst and at the same time reduce the thermal degradation and ageing of the catalyst to the minimum possible extent by adopting an approach with Dynamic Catalytic Converter System (DCCS). The emission tests were conducted at the cold start of a 4 cylinder spark ignition engine with DCCS at different positions of the catalyst at no load conditions. Also emission tests were conducted with pre-catalysts of 20% volume and 40% volume of the main catalytic converter and with air pre-heater at the exhaust manifold prior to main catalytic converter. It was established that considerable reduction in the time to light off was achieved by using DCCS and light-off time was further reduced by using pre-catalysts and air pre-heater as compared to the conventional catalysts. It was observed that DCCS with air pre-heater delivering air at 80°C and at 20lpm air flow rate brings down the time to light off to 10 seconds.
Mahadevan, Ganesan, Subramanian, Sendilvelan
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
Influence of Coolant Temperature and Flow Rate, and Air Flow on Knock Performance of a Downsized, Highly Boosted, Direct-Injection Spark Ignition Engine2017-01-06643/28/2017
The causes of engine knock are well understood but it is important to be able to relate these causes to the effects of controllable engine parameters. This study attempts to quantify the effects of a portion of the available engine parameters on the knock behavior of a 60% downsized, DISI engine running at approximately 23 bar BMEP. The engines response to three levels of coolant flow rate, coolant temperature and exhaust back pressure were investigated independently. Within the tested ranges, very little change in the knock limited spark advance (KLSA) was observed. The effects of valve timing on scavenge flow and blow through (the flow of fresh air straight into the exhaust system during the valve overlap period) were investigated at two conditions; at fixed inlet/exhaust manifold pressures, and at fixed engine torque. For both conditions, a matrix of 8 intake/exhaust cam combinations was tested, resulting in a wide range of valve overlap conditions (from 37 to -53°CA). The results indicate that at the fixed manifold pressure test condition, the effects of cam timing on air flow masked the effects of in-cylinder conditions on KLSA. At fixed engine torque, however there was a 1.2°CA variation in KLSA with no distinguishing trend between valve overlap and KLSA. A trade-off between valve timing and the impact that this has on the boost system requirements was found to be of far greater significance than any benefits that valve timing had on spark advance at this load.
Asif, Mohd, Giles, Karl, Lewis, Andrew, Akehurst, Sam, Turner, Niall
Modelling and Control of Engine Torque for Short-Circuit Flow and EGR Evacuation2017-01-06063/28/2017
Low-Pressure Exhaust Gas Recirculation (LP-EGR) has been shown to be an effective means of improving fuel economy and suppressing knock in downsized, boosted, spark ignition engines. LP-EGR is particularly beneficial at low-speed, high-load conditions, but can lead to combustion instability at lower loads. The transport delays inherent in LP-EGR systems slow the reduction of intake manifold EGR concentrations during tip-out events, which may lead to excessive EGR concentrations at low load. This paper explores leveraging Variable Valve Timing (VVT) as a means of improving the rate of reduction of intake manifold EGR concentration prior to tip-out. At higher boost levels, high valve overlap may result in intake manifold gas passing directly to the exhaust manifold. This short-circuiting behaviour could potentially improve EGR evacuation rates. However, introducing short-circuit flow may lead to lean exhaust flow through the catalyst, and/or necessitate rich in-cylinder conditions that could counteract the fuel economy benefits of increasing high load LP-EGR rates. Therefore, this paper seeks to quantify the improvement in EGR evacuation rate and duration of short circuiting that may be achieved while at boosted conditions with high valve overlap, in preparation for a tip out. To conduct this investigation, a controller is first proposed, capable of regulating torque at boosted operating conditions with high valve overlap and external EGR. This controller extends a published control architecture, by accounting for both short-circuit flow and external EGR. The developed controller is then applied to a GT-Power model to regulate torque during constant torque LP-EGR evacuations, where high valve overlap is shown to improve evacuation times by 15-25%.
Wiese, Ashley, Stefanopoulou, Anna, Buckland, Julia, Karnik, Amey Y.
Thermodynamic Potential of Electrical Turbocharging for the Case of Small Passenger Car ICE under Steady Operation2017-01-05263/28/2017
The proposed paper deals with thermodynamic optimization of highly flexible ICE (variable compression ratio, intake/exhaust VVA) while comparing e-turbocharging concept with classical one. The e-turbocharging approach is based on idea that compressor/turbine has its own electric machine (motor/generator) and that additional electric energy can be supplied/attached from/to engine crank train. Hence it allows independent control of compressor/turbine. On the other hand, classical approach is based on a standard mechanical connection between turbine and compressor. The whole system (flexible engine + boost device) is optimized under steady operation – low load (BMEP of 4 bar), medium load (BMEP of 13 bar), high load (BMEP of 30, 25 and 18 bar) and maximum load are considered. Moreover, 3 combustion concepts are considered – classical SI and CI, and ideal RCCI. Sensitivity study of selected parameters is performed: e.g., efficiency of electric machine(s), HP exhaust manifold volume. All the results are achieved by means of simulation using 0-D/1-D SW tool. The data are analyzed and general conclusions are drawn while focusing on thermodynamic potential of e-turbocharging concept under steady operation.
Vitek, Oldrich, Macek, Jan
Thermomechanical Analysis of Diesel Engine Exhaust Manifold2016-36-025810/25/2016
This study focuses on the Termomechanical Fatigue (TMF) analysis for an exhaust manifold. Bolt tension and temperature field has been applied in order to get variation on stresses, going from room load condition to a full load condition. The temperature field has been acquired from 1D simulation and adjusted to fit experimental values measured on the vehicle. Low cycle fatigue (LCF) has been considered to evaluate the exhaust manifold under the stress cycles produced by temperature fluctuation. Thermal and stress analysis have been performed by Abaqus package. An in-house code has been employed in the fatigue analysis. The bolt torque and the temperature field on the engine and exhaust manifold are the loads considered in the analysis.
de Azevedo Cardoso, Ademar, Andreatta, Ederson Claudio
Investigations on Ventilation Strategies for SI Cylinder Deactivation Based on a Variable Valve Train2016-01-234610/17/2016
Advanced SI engines for passenger cars often use the cylinder deactivation technology for dethrottling and thus achieving a reduction of fuel consumption. The gas exchange valves of the deactivated cylinders are closed permanently by a zero lift of the cams. The solutions for cylinder deactivation can vary in the kind of gas composition included in the deactivated cylinders: charge air, exhaust gas or vacuum. All these strategies have in common the frequent loss of captured charge mass from cycle to cycle. Their two-stroke compression-expansion cycle additionally intensifies this phenomenon. Thus, a significant decrease of the minimum cylinder pressure can cause an undesired entry of lubricant into the combustion chamber. The idea was to ventilate the generally deactivated cylinders frequently to compensate the loss of captured cylinder charge mass. The task was to keep the minimum cylinder pressure above a certain limit to prevent the piston rings from a failure. However, a compromise has to be found about the value of IMEP the deactivated cylinders perform in dependence of the included charge mass. The experimental design for this investigation contains a large variety of parameters: type of inclusion, choice of ventilation valves, phase, intensity and frequency of ventilation. Some parametric combinations can be an interesting compromise. They use a ventilation phase at BDC_HP 180°CA before firing TDC in contact to the intake manifold or at BDC_GE 180°CA after firing TDC in contact to the exhaust manifold. Both advantageous strategies use small valve lift curves and low ventilation frequencies.
Gottschalk, Wolfram, Fink, Rene, Schultalbers, Matthias
Thermo-Mechanical Fatigue Study of Gasoline Engine Exhaust Manifold Based on Weak Coupling of CFD and FE2016-01-235010/17/2016
This paper combines fluid software STAR-CCM+ and finite element software ABAQUS to solve the temperature field of this Gasoline engine exhaust manifold based on loose coupling method. Through the simulation of car parking cooling - full load condition at full speed, we estimate thermal fatigue life of the exhaust manifold with the plastic strain increment as the evaluation parameters. It can guide the direction of optimal design of the exhaust manifold. Here we also revealed how the bolt force affects the manifold elastic and plastic behavior.
Liu, Zhien, Chen, Jiangmi, Xiao, Sheng-hao
Probabilistic Isothermal, Anisothermal, and High-Temperature Thermo-Mechanical Fatigue Life Assessment and CAE Implementations2016-01-03704/5/2016
Fatigue life assessment is an integral part of the durability and reliability evaluation process of vehicle exhaust components and systems. The probabilistic life assessment approaches, including analytical, experimental, and simulation, CAE implementation in particular, are attracting significant attentions in recent years. In this paper, the state-of-the-art probabilistic life assessment methods for vehicle exhausts under combined thermal and mechanical loadings are reviewed and investigated. The loading cases as experienced by the vehicle exhausts are first categorized into isothermal fatigue, anisothermal fatigue, and high-temperature thermomechanical fatigue (TMF) based on the failure mechanisms. Subsequently, the probabilistic life assessment procedures for each category are delineated, with emphasis on product validation. Finally, two examples: an isothermal fatigue life assessment for a welded exhaust sub-system, and a high-temperature TMF life assessment for an exhaust manifold (base material) are provided to demonstrate the probabilistic life assessment procedure with the computer-aided engineering (CAE) and finite-element analysis (FEA) tools.
Wei, Zhigang, Qu, Yunfei, Jiang, Dongying, Luo, Limin, Hamilton, Jason, Ellinghaus, Kay, Pieszkalla, Markus
Investigation of the Gas Exchange (Scavenging) on a Single-Scroll Turbocharged Four Cylinder GDI Engine2016-01-10244/5/2016
For scavenging the combustion chamber during the gas exchange, a temporary positive pressure gradient between the intake and the exhaust is required. On a single-scroll turbocharged four cylinder engine, the positive pressure gradient is not realized by the spatial separation of the exhaust manifold (twin-scroll), but by the use of suitable short exhaust valve opening times. In order to avoid any influence of the following firing cylinder onto the ongoing scavenging process, the valve opening time has to be shorter than 180 °CA. Such a short valve opening time has both, a strong influence on the gas exchange at the low-end torque and at the maximum engine power. This paper analyzes a phenomenon, which occurs due to short exhaust valve opening durations and late valve timings: A repeated compression of the burned cylinder charge after the bottom dead center, referred to as “recompression” in this paper. By means of a new energetic analysis (available technical work capacity) the energetic contribution of the recompression to the boost pressure generation has been examined and is presented in this paper. Furthermore two different variable exhaust valve train systems in combination with a part-scroll-separation exhaust manifold are compared in this paper. The aim is to reduce fuel consumption at the nominal power. The two exhaust valve train systems increase the valve opening duration by either a two step system or by a system with the ability to offset the valve timing. It is shown in simulation results how both systems in combination with a prolonged part-scroll-separation in the exhaust manifold reach a potential to reduce fuel consumption up to 10 %.
Wolany, Adalbert, Glahn, Claus, Berner, Hans-Juergen, Bargende, Michael
Development of a New 2.0L I4 Turbocharged Gasoline Direct Injection Engine2016-01-10174/5/2016
It is important to take action regarding environmental issues on a global scale, and automakers are adding downsized turbocharged engines to their line-ups as a means of reducing CO2 emissions, particularly in Europe. Honda has recently announced a next-generation powertrain series that realizes a good balance between environmental performance and driving pleasure. As part of this series, the company has developed a downsized and turbocharged 2.0L gasoline direct injection engine. This is a high-powered sports car engine positioned in the European “hot hatch” category. The development balanced engine power with good environmental performance. The new powertrain featured a range of technologies to enable these demands to be satisfied, including a high-tumble port, a dual VTC(Valve Timing Control),variable exhaust valve lift mechanism, a two-piece water jacket for the exhaust manifold, which has been integrated with the cylinder head, a mono-scroll turbocharger, pistons equipped with cooling channels and lightweight crankshaft. The engine realizes a maximum torque of 400Nm and a maximum output of 228kW, while achieving CO2 emissions of 170g/km in the EU fuel economy test cycle (36.6% maximum thermal efficiency) and clearing the Euro 6b standards. This paper will report on the technologies employed in the new powertrain.
Jono, Mitsutaka, Taguchi, Masayuki, Shonohara, Toshimitsu, Narihiro, Shigeru
Concept Analysis and Initial Results of Engine-Out NOx Estimator Suitable for on ECM Implementation2016-01-06114/5/2016
The interest for NOx estimators (also known as virtual sensors or inferential sensors) has increased over the recent years due to benefits attributed to cost and performance. NOx estimators are typically installed to improve On-Board Diagnostics (OBD) monitors or to lower bill of material costs by replacing physical NOx sensors. This paper presents initial development results of a virtual engine-out NOx estimator planned for the implementation on an ECM. The presented estimator consists of an airpath observer and a NOx combustion model. The role of the airpath observer is to provide input values for the NOx combustion model such as the states of the gas at the intake and exhaust manifolds. It contains a nonlinear mean-value model of the airpath suitably transformed for an efficient and robust implementation on an ECM. The airpath model uses available sensory information in the vehicle to correct predictions of the gas states. The NOx combustion model is a crank-angle resolved model of the incylinder processes, consisting of a pressure-heat release model, zone temperature model and NOx formation model. The NOx combustion model operates in open-loop mode and it is calibrated in offline mode using instrumentation grade in-cylinder pressure sensor. The presented work includes detailed description of the model, explanations of design of experiment, calibration procedure and available validation results.
Kihas, Dejan, Pachner, Daniel, Baramov, Lubomir, Uchanski, Michael, Naik, Priya, Khaled, Nassim
Thermal Analysis of Heavy Duty Engine Exhaust Manifold Using CFD2016-01-06484/5/2016
The exhaust manifold bridges the gap between the engine structure and the hot-end after-treatment system, the burned in-cylinder gases are disposed through the manifold. The automotive exhaust manifolds are designed and developed for providing a smooth flow with low/least back pressure and must be able to withstand extreme heating under very high temperatures and cooling under low temperatures. The paper presents a theoretical study aiming to investigate the feasibility of three different CAE approaches and techniques used for the simulation of exhaust manifold fluid flow and the accompanying thermal distribution. The main difficulty emanates from the pulsating nature of fluid flow inside the engine exhaust manifold. To verify the outcome of each solution experimental measurements of the manifold temperatures have been performed. The predicted metal temperature is then used to carry out the thermo-structure durability analysis to evaluate the design of HD diesel engine exhaust manifold which is out of the scope of this study.
Eroglu, Sinan, Duman, Ipek, Ergenc, Alp, Yanarocak, Rıfat
The Analysis of Phase Separation in Vertical Headers of Microchannel HEs2016-01-02534/5/2016
This paper presents the experimental analysis of separation in vertical headers based on flow visualization. Two-phase separation phenomena inside the header is observed and quantified. Driving forces are analyzed to study the mechanisms for two-phase flow motion and flow regimes. Main tube of the header is made of clear PVC for visualization study. R-134a is used as the fluid of interest and the mass flux from the inlet pass is 55 kg/m2s - 195 kg/m2s. Potential ways to improve two-phase separation are discussed. A model is built to show how separation brings potential benefits to MAC heat exchangers by arranging the flow path.
Li, Jun, Hrnjak, Predrag
Durability Analysis of Heavy Duty Engine Exhaust Manifold Using CFD-FE Coupling2016-01-03754/5/2016
The exhaust manifold is one of the engine components which is used to collect the burned gases from the cylinder head and send it to the exhaust hot end aftertreatment system with low engine backpressure. The main purpose of the automotive exhaust manifolds are providing a smooth flow field and must be able to endure thermo-mechanical loadings. The present paper explains the CAE analysis method to assess the design of exhaust manifold of a heavy duty diesel engine. Coupled computational fluid dynamics (CFD) analyses were performed to solve the flow field within the exhaust system and surface convection loading prediction at fluid side and obtain temperature distribution at solid region of exhaust manifold domain. The metal temperature prediction provided by thermal model is used to carry out the durability analysis of the structure. A transient nonlinear Finite Element Analysis (FEA) is undertaken to simulate the inelastic deformation and predict thermo-mechanical fatigue (TMF) failure. Gasket sealing prediction is another analysis concern which is driven by FEA in exhaust manifolds since any gas leakage affects the engine performance. The use of such CAE approach allows the design and analyses engineers to diagnose critical locations or to find the root cause of manifold failures in an early stage of development and to meet measures in order to remove local structural weaknesses. This minimizes the need for expensive hardware testing, also reducing the overall product development cycle time and cost.
Eroglu, Sinan, Duman, Ipek, Guzel, Ahmet Hamdi, Yilmaz, Rifat
NVH Development of the Ford 2.7L 4V-V6 Turbocharged Engine2015-01-22886/15/2015
A new turbocharged 60° 2.7L 4V-V6 gasoline engine has been developed by Ford Motor Company for both pickup trucks and car applications. This engine was code named “Nano” due to its compact size; it features a 4-valves DOHC valvetrain, a CGI cylinder block, an Aluminum ladder, an integrated exhaust manifold and twin turbochargers. The goal of this engine is to deliver 120HP/L, ULEV70 emission, fuel efficiency improvements and leadership level NVH. This paper describes the upfront design and optimization process used for the NVH development of this engine. It showcases the use of analytical tools used to define the critical design features and discusses the NVH performance relative to competitive benchmarks.
Zouani, Abdelkrim, Stout, Joseph, Hanim, Salah, Gan, Changshen, Dziubinschi, Gabriela, Baldwin, William, Fu, Zhi
Conjugate Heat Transfer and Thermo-Mechanical Heat Cycle Analysis of an Automotive Exhaust Muffler System2015-01-03274/14/2015
Recent progress in computer-aided engineering (CAE) has made it possible to model complex interdisciplinary multiphysics analyses. This paper investigated the sequential coupled thermal-structural analysis by examining the associated thermal stresses under simulated operational conditions close to the real situation. An evaluation of exhaust muffler strain due to thermal stresses was made by coupling Star-CCM+ CFD software and ABAQUS FEM structural analysis software. The study was made to evaluate discovered muffler durability test failure and to develop a countermeasure design. Failure of the muffler internal pipe was discovered after heat cycle durability testing. The internal pipe had broken into two pieces. In the first step, CFD analysis was done by thermo-flow simulation to determine the resulting heat distribution on the muffler assembly when subjected to the prescribed peak duty cycle temperature. The temperature distribution in fluid region in the vicinity of the solid part was subsequently mapped onto the parts' surface and the corresponding FEM nodes using CFD software. In the next step, the nodal temperature values were input as additional boundary conditions using the PREDEFINED FIELDS card. Additional material mechanical properties with temperature dependent characteristics, including the thermal expansion coefficient, were also input into the model. Correlation of the CAE analysis results were then made with the physical test data. In the final step, the FEM modified model was used to develop countermeasures, which satisfied the heat cycle durability test specifications, with alternative internal muffler parts design.
Patterson, Elizabeth M., Goldasteh, Iman, Maaita, Salamah
Effect of Temperature Cycle on Thermomechanical Fatigue Life of a High Silicon Molybdenum Ductile Cast Iron2015-01-05574/14/2015
High silicon molybdenum (HiSiMo) ductile cast iron (DCI) is commonly used for high temperature engine components, such as exhaust manifolds, which are also subjected to severe thermal cycles during vehicle operation. It is imperative to understand the thermomechanical fatigue (TMF) behavior of HiSiMo DCI to accurately predict the durability of high temperature engine components. In this paper, the effect of the minimum temperature of a TMF cycle on TMF life and failure behavior is investigated. Tensile and low cycle fatigue data are first presented for temperatures up to 800°C. Next, TMF data are presented for maximum temperatures of 800°C and minimum cycle temperatures ranging from 300 to 600°C. The data show that decreasing the minimum temperature has a detrimental effect on TMF life. The Smith-Watson-Topper parameter applied at the maximum temperature of the TMF cycle is found to correlate well with out-of-phase (OP) TMF life for all tested minimum temperatures. Fractography and energy dispersive spectroscopy (EDS) are then performed on the tested specimens to determine the difference in failure mechanism as the minimum cycle temperature changes. Based on these observations, it appears that the segregation of magnesium to the grain boundary which occurs near 400°C in HiSiMo DCI influences TMF failure behavior when the TMF temperature cycle passes through 400°C.
Avery, Katherine, Pan, Jwo, Engler-Pinto, Carlos
Comparative Assessment of Elastio-Viscoplastic Models for Thermal Stress Analysis of Automotive Powertrain Component2015-01-05334/14/2015
In this paper, thermal stress analysis for powertrain component is carried out using two in-house developed elasto-viscoplastic models (i.e. Chaboche model and Sehitoglu model) that are implemented into ABAQUS via its user subroutine UMAT. The model parameters are obtained from isothermal cyclic tests performed on standard samples under various combinations of strain rates and temperatures. Models' validity is verified by comparing to independent non-isothermal tests conducted on similar samples. Both models are applied to the numerical analysis of exhaust manifold subject to temperature cycling as a result of vehicle operation. Due to complexity, only four thermal cycles of heating-up and cooling-down are simulated. Results using the two material models are compared in terms of accuracy and computational efficiency. It is found that the implemented Chaboche model is generally more computationally efficient than Sehitoglu model, though they are almost identical in regard to accuracy. This study provides an insight into the necessary information required for fatigue and durability modeling of automotive engine components operating at elevated temperature.
Mao, Jianghui, Engler-Pinto, Carlos, Su, Xuming
The New Toyota 1.2-Liter ESTEC Turbocharged Direct Injection Gasoline Engine2015-01-12684/14/2015
Toyota Motor Corporation is developing a series of engines belonging to its ESTEC (Economy with Superior Thermal Efficient Combustion) development concept. This paper describes the development of 8NR-FTS after the subsequent launch of the 2.0-liter DI Turbocharged 8AR-FTS. 8NR-FTS is a 1.2-liter inline 4-cylinder spark ignition downsized turbocharged direct injection (DI) gasoline engine. By following the same basic concepts as 8AR-FTS engine [1], the 8NR-FTS incorporates various fuel efficient technologies such as a cylinder head with an integrated exhaust manifold, the Atkinson cycle using the center-spooled variable valve timing with mid-position lock system (VVT-iW), and intensified in-cylinder turbulence to achieve high-speed combustion. Instead of the D-4ST (Direct injection 4-stroke gasoline engine Superior version with Turbo) system that incorporates port and direct injection, this engine adopts the D-4T (Direct injection 4-stroke gasoline engine with Turbo) system that performs only DI in each cylinder. In combination with a single-scroll turbocharger, high torque is achieved from low engine speeds by cooperative control with the VVT system. This engine also adopts a stop and start control strategy that achieves speedy and shock-free re-start performance by starting the engine with stratified injection in the first compressed cylinder. The engine can be mated with either a 6-speed manual transmission (6MT) or continuously variable transmission (CVT). Especially with CVT, turbocharger lag duration is reduced by shifting control, and both fun-to-drive dynamic performance and excellent fuel economy are capable by switching two driving mode; “normal” or “sport”.
Shinagawa, Tomohiro, Kudo, Masahito, Matsubara, Wataru, Kawai, Takashi
Exhaust Manifold Durability Subject to Splash Quenching2015-01-17354/14/2015
Exhaust manifold design is one of the more challenging tasks for the engine engineer due to the harsh thermal and severe vibration environment. Extremely high exhaust gas temperatures and dynamic loading combine to subject the manifold to high cyclic stress when the material has reduced fatigue strength due to the high temperature. A long service life before a fatigue failure is the objective in exhaust manifold design. Accumulation of fatigue damage can occur from dynamic loading and thermal loading combined. Thermal mechanical fatigue (TMF) is a primary mechanism for accumulating fatigue damage. TMF typically occurs when a vehicle driving cycle has operating conditions that repeatedly change the exhaust gas temperature between hot and cold. Another way to experience temperature cycling is through splash quenching. Splash quenching was analyzed and found to rapidly accumulate fatigue damage. An experimental and analytical method is presented that quantified splash quenching and the impact on exhaust manifold durability. The number of quenches in the life of a vehicle is uncertain. It is therefore recommended that vehicle packages are designed in such a way that splash quenching of the exhaust manifold is avoided. This will maximize the durability of the hot exhaust components.
Wade, Robert, Hsieh, Jerry C.
Phase Separation in Second Header of MAC Condenser2015-01-16944/14/2015
This paper presents results of the visualization of the separation in the vertical header of the automotive condenser. A prototype of a heat exchanger was made that has inlet in the middle of the header, with 21 microchannel tubes as the first pass. In the second header liquid separates and leaves through 4 microchannel tubes beneath while mostly vapor leaves through 11 microchannel tubes on the top as another exit. That way the 2nd pass has liquid below first pass and vapor above it. R134a was used in the tests. Mass flow at the inlet to the header was in the range 8.4 - 30 g/s (mass flux of 54 kg/m2·s-193 kg/m2·s) and quality at the inlet to second header was varied over a range of 0.05 to 0.25, to see their impact on the separation of two-phase flow inside the transparent header. Visualization was performed to better understand and define the physical parameters that dominate the separation phenomena. Efficiencies of separation are defined to quantify the separation effect of the special design of headers, which could affect the amount of heat exchanged in the condenser.
Li, Jun, Hrnjak, Predrag
Development of the Combustion System for General Motors' High-Efficiency Range Extender Ecotec Small Gas Engine2015-01-12724/14/2015
General Motors has developed an all-new Ecotec 1.5 L range extender engine for use in the 2016 next generation Voltec propulsion system. This engine is part of a new Ecotec family of small displacement gasoline engines introduced in the 2015 model year. Major enhancements over the range extender engine in the current generation Voltec propulsion system include the adoption of direct injection (DI), cooled external exhaust gas recirculation (EGR), and a high 12.5:1 geometric compression ratio (CR). Additional enhancements include the adoption of high-authority phasers on both the intake and exhaust camshafts, and an integrated exhaust manifold (IEM). The combination of DI with cooled EGR has enabled significant thermal efficiency gains over the 1.4 L range extender engine in the current generation Voltec propulsion system at high engine loads. The addition of a high geometric CR and high-authority camshaft phasers for extended late intake valve closing (LIVC) operation has enabled improved low- and mid-load engine efficiency. The combination of DI and high-authority camshaft phasers has minimized the full-load engine torque loss inherent with traditional high CR and LIVC implementations. The combustion system was developed with extensive use of computational fluid dynamics (CFD) simulation for optimization of in-cylinder mixing and combustion. These tools aided in the sorting and selection of the combustion chamber, ports, piston, and fuel injector. Extensive single- and multi-cylinder engine testing and development was also employed to refine and optimize the engine combustion system.
Jocsak, Jeffrey, White, David, Armand, Cedric, Davis, Richard S.
Analysis of Engine Walls Thermal Insulation: Performance and Emissions2015-01-16604/14/2015
This paper presents an experimental analysis on the effect of thermal insulation of engine internal walls on the performance and emissions of a heavy-duty diesel engine. Some parts of the engine, like pistons, cylinder head and exhaust manifold were thermally insulated from gas contact side in order to reduce heat losses through the walls. Each component has been analyzed, independently, and in combination with others. The results have been compared with that of the original engine configuration. The analysis focuses on NOx and, smoke emissions along with brake specific fuel consumption. In order to take advantage of the engine insulation, an optimization of the air management and injection settings was finally performed, which provided the best combination for each engine configuration. The results showed that, on the one hand maintaining the same level of NOx, soot emissions is reduced using insulated cylinder head and insulated pistons, but these configurations increase the fuel consumption. On the other hand the specific fuel consumption is reduced using insulated exhaust manifolds, being this the only configuration that improves both NOx-Soot and NOx-BSFC tradeoff.
Serrano, Jose Ramon, Arnau, Francisco Jose, Martin, Jaime, Hernandez, Manuel, Lombard, Benoit
Turbocharger Matching Method for Reducing Residual Concentration in a Turbocharged Gasoline Engine2015-01-12784/14/2015
In a turbocharged engine, preserving the maximum amount of exhaust pulse energy for turbine operation will result in improved low end torque and engine transient response. However, the exhaust flow entering the turbine is highly unsteady, and the presence of the turbine as a restriction in the exhaust flow results in a higher pressure at the cylinder exhaust ports and consequently poor scavenging. This leads to an increase in the amount of residual gas in the combustion chamber, compared to the naturally-aspirated equivalent, thereby increasing the tendency for engine knock. If the level of residual gas can be reduced and controlled, it should enable the engine to operate at a higher compression ratio, improving its thermal efficiency. This paper presents a method of turbocharger matching for reducing residual gas content in a turbocharged engine. The turbine is first scaled to a larger size as a preliminary step towards reducing back pressure and thus the residual gas concentration in-cylinder. However a larger turbine causes a torque deficit at low engine speeds. So in a following step, pulse separation is used. In optimal pulse separation, the gas exchange process in one cylinder is completely unimpeded by pressure pulses emanating from other cylinders, thereby preserving the exhaust pulse energy entering the turbine. A pulse-divided exhaust manifold enables this by isolating the manifold runners emanating from certain cylinder groups, even as far as the junction with the turbine housing. This combination of appropriate turbine sizing and pulse-divided exhaust manifold design is applied to a Proton 1.6-litre CamPro CFE turbocharged gasoline engine model. The use of a pulse-divided exhaust manifold allows the turbine to be increased in size by 2.5 times (on a mass flow rate basis) while maintaining the same torque and power performance. As a consequence, lower back pressure and improved scavenging reduces the residual concentration by up to 43%, while the brake specific fuel consumption improves by approx. 1%, before any modification to the compression ratio is made.
Ismail, Muhammad Izzal, Costall, Aaron, Martinez-Botas, Ricardo, Rajoo, Srithar
Design of the Exhaust Manifold of a Turbo Charged Gasoline Engine Based on a Transient Thermal Mechanical Analysis Approach2014-01-288210/13/2014
The present paper describes a CAE analysis approach to evaluate the design of exhaust manifold of a turbo charged gasoline engine. It allows design engineers to identify structural weakness at the early stage or to find the root cause of exhaust manifold failures. A transient none-linear finite element method is used to calculate the plastic deformation and thermal mechanical behaviors of the exhaust manifold assembly during thermal shock cycles, which include rated speed full load, rated speed motored and idle speed conditions. A transient heat transfer simulation is performed to provide thermal boundary conditions for the nonlinear stress/strain analysis. The finite element model includes a part of cylinder head, exhaust manifold, gaskets, turbo charger housing, catalytic converter, brackets, bolts and nuts. The results show that plastic deformation is the main cause of manifold cracking and the manifold flange distortion causes the exhaust leakage. The simulation results indicate that predicted crack locations and leak area are in agreement with that from the engine durability test. Based on the baseline calculation results, local geometric modifications are made, which include changed shape of the inlet flange, changed location of anchor bolt hole and removing the internal baffle. For the modified design of the exhaust manifold, the cumulated equivalent plastic strain and the gasket sealing pressure at the end of third cycle meet the guideline limits. The modified exhaust manifold successfully passed all tests. Finally, general design recommendations of exhaust manifold are summarized in the paper.
Chen, Ming, Wang, Yanjun, Wu, Wenrui, Xin, Jun
Performance Sensitivity to Exhaust Valves and Turbine Parameters on a Turbocompound Engine with Divided Exhaust Period2014-01-259710/13/2014
Turbocompound can utilize part of the exhaust energy on internal combustion engines; however, it increases exhaust back pressure, and pumping loss. To avoid such drawbacks, divided exhaust period (DEP) technology is combined with the turbocompound engine. In the DEP concept the exhaust flow is divided between two different exhaust manifolds, blowdown and scavenging, with different valve timings. This leads to lower exhaust back pressure and improves engine performance. Combining turbocompound engine with DEP has been theoretically investigated previously and shown that this reduces the fuel consumption and there is a compromise between the turbine energy recovery and the pumping work in the engine optimization. However, the sensitivity of the engine performance has not been investigated for all relevant parameters. The main aim of this study is to analyze the sensitivity of this engine architecture in terms of break specific fuel consumption to different parameters concerning the gas exchange such as blowdown valve timing, scavenging valve timing, blowdown valve size, scavenging valve size, discharge coefficients of blowdown and scavenging ports, turbine efficiency, turbine size and power transmission efficiency. This study presents the sensitivity analysis of the turbocompound DEP engine to these parameters and defines a set of important parameters that should be examined in experimental studies.
Aghaali, Habib, Angstrom, Hans-Erik
Turbocharger Matching and Assessments of Turbocharger Effect on a Diesel Engine based on One-Dimensional Simulation2014-01-255710/13/2014
The aim of this paper is to choose the convenient turbocharger for the OM355 naturally aspirated diesel engine and turn it to a turbocharged one. For this, 1D1 computer simulation code is used and simulation results are validated with experimental measurements. Finally, by selecting a proper turbocharger, engine power increases about 50% and specific fuel consumption decreases about 4%. Moreover, effects of exhaust manifold geometry and ambient condition on performance parameters of the turbocharged diesel engine are investigated.
Shamsderakhshan, Mohamadamin, Kharazmi, Shahaboddin
Study on the Unsteady Heat Transfer of Engine Exhaust Manifold Based on the Analysis Method of Serial2014-01-17114/1/2014
In order to predict the thermal fatigue life of the internal combustion engine exhaust manifold effectively, it was necessary to accurately obtain the unsteady heat transfer process between hot streams and exhaust manifold all the time. This paper began with the establishment of unsteady coupled heat transfer model by using serial coupling method of CFD and FEA numerical simulations, then the bidirectional thermal coupling analysis between fluid and structure was realized, as a result, the difficulty that the transient thermal boundary conditions were applied to the solid boundary was solved. What's more, the specific coupling mode, the physical quantities delivery method on the coupling interface and the surface mesh match were studied. On this basis, the differences between strong coupling method and portioned treatment for solving steady thermal stress numerical analysis were compared, and a more convenient and rapid method for solving static thermal stress was found. Finally, aiming at the thermal stress analysis of steady and unsteady temperature fields, the thermal fatigue life of the exhaust manifold was estimated in application of Manson-Coffin formula, giving a general qualitative analysis.
Zhien, Liu, Wang, Xiaomin, Yan, Zhang, Li, Xueni, Xu, Yu
TMF Life Prediction of High Temperature Components Made of Cast Iron HiSiMo: Part I: Uniaxial Tests and Fatigue Life Model2014-01-09154/1/2014
HiSiMo cast irons are frequently used as material for high temperature components in engines as e.g. exhaust manifolds and turbo chargers. These components must withstand severe cyclic mechanical and thermal loads throughout their service life. The combination of thermal transients with mechanical load cycles results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material and, after a certain number of loading cycles, to failure of the component. In this paper (Part I), the low-cycle fatigue (LCF) and TMF properties of HiSiMo are investigated in uniaxial tests and the damage mechanisms are addressed. On the basis of the experimental results a fatigue life model is developed which is based on elastic, plastic and creep fracture mechanics results of short cracks, so that time and temperature dependent effects on damage are taken into account. The model can be used to estimate the fatigue life of components by means of finite-element calculations (Part II of the paper).
von Hartrott, Philipp, Seifert, Thomas, Dropps, Steven
TMF Life Prediction of High Temperature Components Made of Cast Iron HiSiMo: Part II: Multiaxial Implementation and Component Assessment2014-01-09054/1/2014
HiSiMo cast irons are frequently used as material for high temperature components in engines as e.g. exhaust manifolds and turbo chargers. These components must withstand severe cyclic mechanical and thermal loads throughout their life cycle. The combination of thermal transients with mechanical load cycles results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material and, after a certain number of loading cycles, to failure of the component. In Part I of the paper, a fracture mechanics model for TMF life prediction was developed based on results of uniaxial tests. In this paper (Part II), the model is formulated for three-dimensional stress states, so that it can be applied in a post-processing step of a finite-element analysis. To obtain reliable stresses and (time dependent plastic) strains in the finite-element calculation, a time and temperature dependent plasticity model is applied which takes non-linear kinematic hardening into account. The material properties of the model are identified from the results of the uniaxial test. The plasticity model and the TMF life model are applied to assess the lifetime of an exhaust manifold.
Seifert, Thomas, Hazime, Radwan, Dropps, Steven
Damage Mechanisms of Stainless Steels under Thermal Fatigue2014-01-09174/1/2014
Thermal fatigue of austenitic and ferritic stainless steel grades has been experimentally and numerically investigated. A special test has been developed to determine the thermal fatigue resistance of clamped V-shaped specimens. This test permits to impose thermal cycle by alternating resistance heating and air cooling. The thermal fatigue life of a specimen is expressed as the number of cycles to failure. For a given grade, the fatigue life depends on the maximal and minimal temperature of the cycle, holding time at the maximal temperature and specimen thickness. The advantage of this V-shape test is that it is a simple procedure quite representative of the thermal fatigue process occurring in an exhaust manifold. This test is well suited to perform a study of damage mechanisms and to compare stainless steel grades. Examination of the failed specimens indicated that cracks could be mainly attributed to out-of-phase (OP) thermal fatigue process especially in case of ferritic grades. For austenitic steels (AISI304 EN1.4301, AISI321 EN1.4541 or AISI308 EN1.4828) at a critical temperature or above, an in-phase (IP) thermal fatigue mechanism is coupled with oxidation and creep, which are further significantly reducing the lifetime. Therefore, the service temperature range of austenitic grades is more limited than ferritic grades. Despite their lower yield stress at high temperature, ferritic grades exhibit a very good thermal fatigue resistance at elevated peak temperatures because of their very good cyclic oxidation behavior, creep resistance and their low coefficient of thermal expansion. Consequently a dedicated titanium or niobium stabilized ferritic offer was developed for the hot part of the exhaust system (from manifold to catalytic converter) that includes 14%Cr (K11X 429/425 1.4595), 17%Cr (K41X 441 1.4509) and 19%Cr (K44X modified 444 1.4521) grades in order to cover the peak temperature range from 900°C to 1050°C.
Santacreu, Pierre-Olivier, Faivre, Laurent, Acher, Antoine
1-D Simulation Study of Divided Exhaust Period for a Highly Downsized Turbocharged SI Engine - Scavenge Valve Optimization2014-01-16564/1/2014
Fuel efficiency and torque performance are two major challenges for highly downsized turbocharged engines. However, the inherent characteristics of the turbocharged SI engine such as negative PMEP, knock sensitivity and poor transient performance significantly limit its maximum potential. Conventional ways of improving the problems above normally concentrate solely on the engine side or turbocharger side leaving the exhaust manifold in between ignored. This paper investigates this neglected area by highlighting a novel means of gas exchange process. Divided Exhaust Period (DEP) is an alternative way of accomplishing the gas exchange process in turbocharged engines. The DEP concept engine features two exhaust valves but with separated function. The blow-down valve acts like a traditional turbocharged exhaust valve to evacuate the first portion of the exhaust gas to the turbine. While the scavenge valve feeding the latter portion of the exhaust gas directly into the low resistant exhaust pipe behaves similarly to valves in a naturally aspirated engine. By combining the characteristics of both turbocharged and naturally aspirated engines, high backpressure between the turbine inlet and the exhaust port is maintained in the blowdown phase while significant reduction of the backpressure could be achieved in the latter displacement phase. This is directly beneficial for pumping work and residual gas scavenging. Combustion phasing & stability and turbocharger efficiency could also benefit from such concept. This simulation study was carried out using a validated 1D model of a highly downsized SI engine. Two degrees of freedom including the lift and the duration of the scavenge valve were optimized to achieve minimum BSFC. The potential for higher attainable BMEP was also briefly investigated at low engine speed.
Hu, Bo, Akehurst, Sam, Brace, Chris, Copeland, Colin, Turner, James
A Critical Assessment of Factors Affecting the Flammability of R-1234yf in a Frontal Collision2014-01-04194/1/2014
An evaluation methodology has been developed for assessing the suitability of R-1234yf in vehicles. This relates primarily to evaluating the flammability of R-1234yf in the engine compartment during a frontal collision. This paper will discuss the process followed in the methodology, the technical rationale for this process, and the results of the analysis. The specific types of analysis included in the methodology are: exhaust-system thermal characterization, computer simulated crash tests, actual crash tests, teardown and examination of crashed parts, and releases of refrigerant onto hot exhaust manifolds. Each type of analysis was logically ordered and combined to produce a comprehensive evaluation methodology. This methodology has been applied and demonstrates that R-1234yf is difficult to ignite when factors that occur in frontal crashes are simultaneously considered. Factors considered in this analysis include: crush and deformation of the vehicle structure, airflow in the engine compartment, exhaust system temperatures during different driving scenarios, and coolant release due to damage of the engine coolant system. Such findings support the conclusion of the Society of Automotive Engineers Cooperative Research Team (SAE CRP1234-4) regarding R-1234yf usage: “risks are still very small compared to the risks of a vehicle fire from all causes and well below risks that are commonly viewed as acceptable by the general public.” This methodology can provide a representative and more realistic assessment of the suitability of R-1234yf in automotive air-conditioning systems. The evaluation methodology can be applied to any vehicle.
Styles, Bryan, Santrock, Jeffrey, Vincent, Curtis, Leffert, Michael, Putcha, Narasimha
Modularity Adoption in Product Development: A Case Study in the Brazilian Agricultural Machinery Industry2013-01-90931/15/2014
Facing a competitive and globalized market and with increasingly demanding customers, companies must constantly seek the development of practices in the development of new products. One of the current practices is the adoption of modularity. In that sense, the objective of this paper is to conduct an analysis of this practice in a Brazilian company, which manufactures agricultural machinery. The applicability of modular design in current products is focused. Therefore, a case study approach has been chosen. First, a review of the scientific literature was conducted, followed by field research, for collecting data based on interviews with product engineers and technical documentation. The case study shows the applicability of the modular design concept in a combine header, by increasing the number of repeated components. The modular header approach facilitates the implementation of engineering changes and allows greater standardization of components. In addition, it contributes for greater flexibility, as it is possible to create a wider range of product configurations and satisfy specific customer needs. The proposed modular design can provide further benefits such as product cost reduction due to larger lots of parts. In recent years, the company's forecasts have indicated that the market will require high-power harvesting machines with greater capacity. Therefore increasing diversification in the composition of the header product family is demanded. The use of modular headers can facilitate proper reaction to variable market demands, as each module can be produced, stored and adapted according to production orders.
Mayer de Ávila, Rodrigo, Borsato, Milton
The Analysis of Crack Mechanism and Estimate of Life Time by the Vibration Measurement of Stainless Exhaust Manifold in Firing Condition2013-01-264310/14/2013
SUS exhaust manifold is weaker than cast iron in aspect of high temperature vibration. So as to improve reliability of SUS exhaust manifold and get over gas temperature limit, exhaust manifold vibration mode and level has to be decreased. And because of error and limit of conventional modal analysis, we measured vibration mode and level of SUS exhaust manifold directly in engine firing condition. To measure vibration of hot parts(600∼800°C) in engine, we used special cooling device at base of accelerometer. Thus we developed analysis method of SUS exhaust manifold crack mechanism. We came to know the accurate vibration mode and level of SUS exhaust manifold in hot condition. Besides, we found out in proportion as vibration level increases endurance life decreases.
Kim, Han Sang, Park, Sang Joon
Modeling and Control of Single Turbocharger with High Pressure Exhaust Gas Recirculation Diesel Engine2013-01-264910/14/2013
The regulation of NOx emission from a diesel engine is becoming stricter by the environmental agency and furthermore, EGR has been adopted to reduce NOx emission. Air flow control of a diesel engine combined with turbocharger and EGR is complicated because turbocharger and EGR are coupled physically. This paper examines the design of a model based control structure for diesel engine with a turbocharger and EGR. Model based control provides desirable control strategies from the physical analysis of an engine model. Air fraction and exhaust manifold pressure target based control simulation was conducted in this research. Engine is highly nonlinear and susceptible to uncertainties. To overcome this problem, a robust controller was designed by using a sliding mode control method.
Jung, Hojin, Jin, Hyomin, Choi, Seibum, Ko, Minseok
Logistics Product Data Reports HandbookTAHB0007_1 (Current)5/1/2013
This document describes a set of standardized reports that can be generated using the logistics product data elements contained in GEIA-STD-0007-B. Each report is defined by selection options, processing, format, report sequence, and data sources. The selection options paragraph identifies recommended mandatory and optional selections that can be made by the user to tailor the report content. The processing paragraph identifies qualifying criteria for report data, report calculations, and specific instructions regarding how the data should be presented on the report. Each report has a sample report showing its format. Report sequences specify the sort criteria for a given report, and each Part/Section within a report. There is an attached listing of data sources for the elements that are on a report. The listing provides the report header for each element; and its GEIA-STD-0007-B data element/attribute along with the appropriate entity. The data source listings were developed by viewing each report in a left-to-right, top-to-bottom sequence. If an element shows up more than once on a report and each subsequent occurrence is pulled from the same GEIA-STD-0007-B Entity as the previous one, then that element is only listed once in the data source listing. However, if an element is listed more than once and each occurrence is pulled from different GEIA-STD-0007-B Entities, then that element will be listed for each report occurrence. Report development can be accomplished via a manual process or via software. The latter approach is recommended since software is available on the market that meets the requirements for each of the reports in this handbook.
LCLS Life Cycle Logistics Supportability
Multi-User Space Link Extension (SLE) SystemTBMG-163515/1/2013
The Multi-User Space (MUS) Link Extension system, a software and data system, provides Space Link Extension (SLE) users with three space data transfer services in timely, complete, and offline modes as applicable according to standards defined by the Consultative Committee for Space Data Systems (CCSDS). MUS radically reduces the schedule, cost, and risk of implementing a new SLE user system, minimizes operating costs with a “lights-out” approach to SLE, and is designed to require no sustaining engineering expense during its lifetime unless changes in the CCSDS SLE standards, combined with new provider implementations, force changes.
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