Browse Topic: Compressors

Items (229)

Experimental Evidence to Influence Design of Novel Low Lubrication Method for Rotorcraft Secondary Lubrication Systems

F-0081-2025-0279

5/20/2025

This paper presents experimental research aimed at developing novel low lubrication methods for rotorcraft and jet engines, focusing on sustaining minimal lubrication to prevent catastrophic bearing failure during loss of lubrication (LoL) events or to increase fuel consumption performance on once-through, fuel-oil bearing lubrication engines. Utilizing two high-speed bearing test rigs simulating low and high thrust class engine conditions, the study establishes lower bounds for oil flow rates necessary to maintain thermal stability and prevent thermal runaway in hybrid ball bearings. These findings inform the design of the Zulu Pod (ZPod), a passively driven, self-contained oil delivery system that uses engine compressor bleed air to precisely meter lubricant flow. Engine test stand results demonstrate that replacing traditional fuel-oil lubrication with the ZPod system reduces thrust specific fuel consumption (TSFC) by an average of 7%, with up to 11% savings, without compromising engine thrust or bearing health. The ZPod offers a simplified, efficient alternative to fuel-lubricated systems by eliminating fuel diversion for lubrication, enhancing fuel efficiency, and maintaining bearing performance in attritable or single-use engines. Additionally, the study highlights the potential of minimal lubrication supplied by the ZPod to extend operational life during LoL scenarios, enabling safer aircraft recovery. Future work will focus on extending testing to higher thrust classes and optimizing ZPod designs for broader applications.

Boersma, Pieter, Currier, Todd, Ferrante, Jason, Rosenthal, Julius

Method for Evaluating the Flow Properties of Pumpable Sealers

J2025_202101 (Current)

1/7/2021

This SAE Recommended Practice sets forth a method for evaluating the flow properties of automotive sealers that have been dispensed via a high pressure automatic system.

Materials, Processes and Parts Council

Safety and Design Standards for Motor Vehicle Refrigerant Vapor Compression Systems

J639_202011 (Current)

11/9/2020

This SAE Standard applies to refrigerant vapor compression systems that provide cooling and/or heating for passenger cars, light trucks, and commercial vehicles (on and off road) that use automotive type mobile air conditioning (MAC) systems. Large trucks, buses, and other vehicles that do not use typical automotive A/C systems or use refrigerants not listed in this document are not covered by this standard. This standard covers vehicles with MAC systems using belt driven compressors and electric motor driven compressors. This document provides industry-recognized standards for the design, assembly, and test of MAC systems, including necessary service equipment, and is intended to cover all phases of the lifetime of MAC systems to minimize environmental, health, and safety impacts. The standards listed in this document cover the currently accepted industry guidelines and procedures. The standards can be used as requirements for regulatory authorities to meet minimum environmental, health, and safety requirements. Also included are cautionary statements for the service industry to alert technicians to the inadvisability and possible health or safety effects associated with venting refrigerant during service. It is not intended to restrict the use, or further development of, other types of refrigerants or refrigeration systems for MAC applications. This document may be amended, or additional safety standards created, should other refrigerants or refrigeration systems become practical. This document addresses only HFC-134a (R-134a), carbon dioxide (R-744), HFO-1234yf (R-1234yf), and HFC-152a (R-152a) refrigerants. For R-152a refrigerants, this standard will only apply to secondary loop systems. To prevent system contamination, all refrigerants used in MAC vapor compression systems require unique service fittings and service equipment. The unique service fittings are intended to significantly reduce the potential for refrigerant cross-contamination during service activities. CFC-12 (R-12) is no longer in use in new MAC systems. The service fitting description is maintained as a reference for older vehicles still in use. When retrofitting an R-12 system to use R-134a or when removing R-12 (during vehicle disposal), use service equipment designed for R-12 and certified to meet the requirements of SAE J1990 (R-12 recovery and recycle equipment).

Interior Climate Control Vehicle OEM Committee

Energy Recovery Rate from an Electric Air-Cycle System under the Cruising Altitude and Speed

2019-01-19059/16/2019

A new electric air-cycle system of aircrafts is investigated focusing on energy recovery from the exhaust air. The working fluid of air has the higher energy level in the cabin than in the outside during the cruise because the outside air is at low pressure and low temperature. In the system, by setting a recovery turbine behind the cabin, the discharged energy can be collected, although the working fluid through the system has been only discharged from the cabin into the outside. We perform a thermodynamic cycle-analysis, where the temperature, pressure, entropy, etc. are calculated at each position of the cycle by considering the two pressure ratios of the compressors as variable parameters to show T-s diagram. In addition, we obtain an energy recovery rate of the recovery energy to the necessary power for the electric compressor. The energy recovery rate is roughly estimated 40-80% under the reasonable practical operating conditions.

Adachi, Takahiro, Seki, Naoki, Oyori, Hitoshi, Muraoka, Mikio

Validation and Instrumentation of a Small Modular Multi-Stage Axial Compressor for Ice Crystal Icing Research

2019-01-19406/10/2019

The National Research Council of Canada (NRC) has undergone the development of a Small Axial Compressor Rig for modelling altitude ice accretion in aircraft engines. The rig consists of two axial compressor stages measuring approximately 150mm in diameter, an extension duct to allow residence time for partial melting of ice crystals and a test piece. The axial compressor stages are intended to provide realistic engine conditioning such as fracture, pressure rise, temperature rise and centrifuging of glaciated ice crystals entering the rig. The rig was designed for use in altitude icing wind tunnels such as the NRC’s altitude icing wind tunnel (AIWT), research altitude test facility (RATFac.), and those of other organization such as NASA Glenn and Technical University of Braunshweig. Previous development work [1] provided partial validation of the aerodynamic performance of just the first compressor stage at 90% power. Recent development work has concluded the aerodynamic validation of both the first and the second stages and performance was found to be satisfactory for purpose. A prediction of the ice accretion behavior of the rig based on validated performance is provided. Details of the instrumentation scheme including measurement technique for the radial distribution of ice crystal downstream of the compressor stages, and measurement of particle sizes before and after each stage are also presented.

Neuteboom, Martin, Chalmers, Jennifer, Currie, Thomas

Microwave Technique for Liquid Water Detection in Icing Applications

2019-01-19306/10/2019

The partial melting of ingested ice crystals can lead to ice accretion in aircraft compressors, but accurately measuring the relatively small fraction of liquid water content in such flows is challenging. Probe-based methods for detecting liquid water content are not suitable for deployment within turbofan engines, and thus alternatives are sought. Recent research has described approaches based on passive microwave sensing. We present here an approach based on active microwave transmission and reflection, employing a vector network analyzer. Utilization of both transmission and reflection provides additional data over and above emission or transmission only, and permits a more controllable environment than passive sensing approaches. The paper specifically addresses the question of whether such an approach is viable within the context of representative icing wind tunnel and engine flow conditions. A quasi-thermal equilibrium approach is presented herein to estimate the melting ratio during microwave analysis of samples at 0 °C. Experimental results using microwaves in the 2.45GHz region are presented, and post-processing methods investigated. This is followed by an investigation of detection limits for ice accretion in the sub-gram range. The results indicate the potential of the technique, with a number of avenues evident for further research.

Leis, John, Buttsworth, David, Saeed, Ramiz, Saleh, Khalid, McGilvray, Matthew, Gillespie, David

Two-Way Flow Coupling in Ice Crystal Icing Simulation

2019-01-19666/10/2019

Numerous turbofan power-loss events have occurred in high altitude locations in the presence of ice crystals. It is theorized that ice crystals enter the engine core, partially melt in the compressor and then accrete onto stator blade surfaces. This may lead to engine rollback, or shed induced blade damage, surge and/or flameout. The first generation of ice crystal icing predictive models use a single flow field where there is no accretion to calculate particle trajectories and accretion growth rates. Recent work completed at the University of Oxford has created an algorithm to automatically detect the edge of accretion from experimental video data. Using these accretion profiles, numerical simulations were carried out at discrete points in time using a manual meshing process. That work showed that flow field changes caused by a changing accretion profile had significant effects on the collection efficiency of impinging particles, ultimately affecting the mass of accreted ice and its shape. This paper discusses the development of the ICICLE numerical ice crystal icing code to include a fully automated two-way coupling between the accretion profile and flow field solution, to account for these effects. The numerical strategy; geometry redefinition, mesh update and flow field solution are discussed, followed by a comparison to experimental ice accretion of a simple 2D geometry and model predictions with and without flow field updating. The results showed that significant changes in leading edge accretion profiles were numerically predicted when the only the geometry was updated. Further changes then occurred when the flowfield was also updated.

Connolly, Jonathan Paul, McGilvray, Matthew, Gillespie, David, Bucknell, Alex, Parker, Liam, Jones, Geoffrey, Collier, Benjamin

Prediction of Broadband Noise in an Automotive Centrifugal Compressor with Three-Dimensional Computational Fluid Dynamics Detached Eddy Simulations

2019-01-14876/5/2019

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

Surge Prediction in a Single Sequential Turbocharger (SST) Compressor Using Computational Fluid Dynamics

2019-01-14906/5/2019

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

Swept Volume Approach for the Characterization of Pumping Loss of Shrouded Meshed Cylindrical Gears

F-0075-2019-14681

5/13/2019

High speed rotorcraft transmissions are subject to load-independent power losses consisting of drag and pumping loss. Tightly conforming shrouds enclosing the transmission gears are often incorporated to reduce the drag component of the total load independent losses. However, tightly conforming axial shrouding can result in an increase in the pumping loss component. Quantifying the pumping loss of shrouded gear transmissions has been the subject of many studies. This study presents a new approach for estimating pumping loss based on the concept of swept volume borrowed from the positive displacement pump and compressor industry. In this study, pumping loss of shrouded gear transmissions is considered to be related to the swept volume of the gear sets and the downstream flow resistance created by the shroud clearances. The drag loss and pumping loss of a spur gear pair have been determined through testing using the NASA Glenn Research Center Gear Windage Test Facility. The results from this testing have been compared to theoretical results using the formulations presented in this study. Good correlation exist between the test pumping power loss and the predicted pumping power loss for tightly conforming axial shroud configurations.

Hurrell, Michael, Delgado, Irebert

Potential Improvements in Turbofan’s Performance by Electric Power Transfer

2018-01-196210/30/2018

Bleeding in engines is essential to mitigate the unmatched air massflow between low and High Pressure (HP) compressors at low speed settings, thus avoiding unstable operation due to surge and phenomena. However, by emerging the More Electric Aircraft (MEA) the engine is equipped with electrical machines on both high and Low Pressure (LP) spools which enables transfer of power electrically from one spool to another and hence provides the opportunity to operate engine core components closer to their optimum design point at off-design conditions. At lower power setting of the engine, HPC speed can be increased by taking power from LP shaft and feeding it to HP shaft which can lead to the removal of the bleeding system which in turn reduces weight and fuel consumption and help to overcome engine instability issues. Fuel consumption can be decreased by decreasing inconsistent thrust with the aircraft mission for flight and ground idle settings. This paper investigates the idea of power circulation between shafts using a turbofan model developed using Intermediate Control Volume (ICV) method. Results show considerable improvement in efficiency while dynamic response for severe transient maneuvers is also improved considerably with the new control configuration.

Balaghi Enalou, Hossein, Le-Peuvedic, Jean-Marc, Rashed, Mohamed, Bozhko, Serhiy

Development of a Climate and Altitude Simulation Test Bench for Handheld Power Tools

2018-32-003310/30/2018

A climate and altitude conditioning test bench was developed at the Institute of Energy Efficient Mobility (IEEM) of Karlsruhe University of Applied Sciences to evaluate the overall sustainability of using innovative biofuels in handheld power tools such as chainsaws, trimmers and blowers under any typical operating condition worldwide. The 6 m3 hermetically sealed and thermally insulated test chamber is large enough to fit the entire power tool. A two-stage refrigeration system with intake air drying and electric heating allows for realistic temperature conditions to be set in the test chamber, ranging from arctic cold to tropical heat (-28 to 45 °C). Altitudes of up to 3500 m above sea level can be simulated using a throttle valve at the inlet of the chamber and a pressure-controlled rotary screw compressor positioned downstream the test chamber outlet. The air-cooled engines to be tested are fully exposed to the ambient conditions inside the test chamber, are able to aspirate the conditioned combustion air freely and release both exhaust gas and waste heat into the chamber environment. In order to control the power tool’s operation when the chamber is closed, an adaptive remote control system was specially developed. It enables automatic engine start-up by cable pull (e.g. for cold start testing), engaging the choke valve as well as operating the throttle lever automatically. This paper discusses the development process, the design, the operating limits of the climate and altitude simulation test bench as well as first tests on the reproducibility of the automatic start procedure, particularly important for future cold start investigations.

Martel, Artur, Scholl, Fino, Weierter, Dennis, Kettner, Maurice

Popcorn-Driven Robotic Actuators

TBMG-3307910/1/2018

When heated, popcorn can expand more than 10 times in size, change its viscosity by a factor of 10, and transition from regular to highly irregular granules with surprising force. These unique qualities can power inexpensive robotic devices that grip, expand, or change rigidity.

Effective Suppression of Surge Instabilities in Turbocharger Compression Systems through a Close-Coupled Compressor Inlet Restriction

2018-01-17149/10/2018

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

Limits and Fits - International Metric Tolerance System

AIR1758A (Current)8/9/2018

This information report provides guidance when the ISO International metric tolerance system for limits and fits per ISO/R286 or ANSI B4.2-1978 is applied on a standard, and also provides a selected series of limits and fits for powerplant construction suitable for holes and shafts up to 500 mm. For holes or shafts over 500 mm or for limits and fits not shown, ISO/R286 should be consulted.

E-25 General Standards for Aerospace and Propulsion Systems

Multi-Axis Voxel-Based CNC Machining of Centrifugal Compressor Assemblies

F-0074-2018-12798

5/14/2018

ABSTRACT The use of computer-aided manufacturing (CAM) software is essential in the rapid production of high-quality computer numerical control (CNC) machining toolpaths for complex parts. Typical CAM software relies on analytical representations of part geometry, where curves and surfaces are described by parametric functions. This paper proposes the use of a novel way to represent part geometry known as a voxel model. A voxel model uses a three-dimensional array of small cubes to represent a part volume; these cubes, or voxels, are the three-dimensional analog of two-dimensional pixels in an image. The use of voxels for a CAM application enables higher surface complexity, simplified collision checking, and more robust analysis of material removal than would be possible with typical parametric CAM. The unique capabilities of the voxel-based CAM approach described in this paper enable rapid production of high-quality 5-axis toolpaths for machining complex parts, such as the centrifugal compressor assembly that is presented in this work.

Kurfess, Thomas, Tucker, Tommy, Silberglied, Chelsea, Lynn, Roby, Saleeby, Kyle, Saldana, Christopher

Oil Circulation Rate in Ejector Cooling Cycles

2018-01-00774/3/2018

In this study, the influence of compressor speed, ejector motive nozzle needle position and evaporator inlet metering valve opening on the oil circulation rates (OCRs) of an automotive R744 transcritical standard ejector cycle was experimentally investigated. Significantly higher OCR (~10%) was observed at the evaporator inlet of the ejector cycle than at the high pressure side. It has been observed that evaporator OCR was increased with increasing compressor speed. When the motive nozzle needle moved towards the nozzle throat, both compressor discharge flow rate and evaporator OCR were observed to be significantly lowered. As the evaporator inlet metering valve opening was adjusted, the compressor mass flow rate did not vary significantly while the evaporator mass flow rate decreased with decreasing metering valve opening. The evaporator OCR decreased from 6.5% to 2.2% as the metering valve opening varied from 86% to 27%.

Zhu, Jingwei, Botticella, Francesco, Elbel, Stefan

Performance Characteristics of a Mobile Heat Pump System at Low Ambient Temperature

2018-01-00764/3/2018

The demand for mobile heat pump systems increases with the growing popularity of electric vehicles. One big challenge of such systems using low pressure refrigerant is the substantial drop of heating capacity at low ambient temperature conditions, when heat is most needed. The low suction density associated with low operating pressure in the evaporator is the major reason for the capacity drop. In extremely low ambient temperature, compressor speed may need to be regulated in order to prevent suction pressure going below atmospheric pressure, hence further reducing heat pumping capability. Other factors like pressure drop induced temperature glide and refrigerant maldistribution in the outdoor evaporator also weakens the system ability to absorb heat from ambient air. This paper presents detailed and in-depth analysis of the performance and limiting factors on low ambient temperature operation of a mobile heat pump system using refrigerant R1234yf. Experimental data are taken for ambient temperatures ranging from −20 to 20 ˚C. Analysis of losses are presented with the aid of a simulation model.

Feng, Lili, Hrnjak, Predrag

Numerical Simulation of Oil Separator of an Automotive Swash Type Compressor

2018-01-04884/3/2018

In the present study a numerical investigation is performed by using computational fluid dynamics (CFD) aiming to figure out and maximize the separation efficiency of an oil separator by changing the various design parameters. A typical automotive swash plate type compressor is chosen for this numerical investigation. Basically oil separation becomes very important where oil return is quite problematic due to the multiple constraints in piping layout design. Efficient oil separation makes the compressor lubrication easy and prevents from seizing during running. It also enhances the heat transfer from heat exchanger by reducing or separating oil from the refrigerant flowing in the air conditioning (AC) circuit. A computational method is proposed to analyze an oil separator fitted in a swash plate compressor. Eulerian multiphase model is employed to simulate the oil and refrigerant mixture model. Separation efficiency is predicted numerically by changing the nozzle diameter, separator diameter and height. Further to that a different approach (based on density difference) is utilized to maximize the separation percentage. It is observed that by employing such approach separation efficiency increased drastically. Thus a numerical method is established for predicting oil separation which becomes key element in the early stage of compressor design to avoid field failure.

Sen, Somnath

Performance Optimization of Compressor Rotor Clutch Sub-assembly Using Electro- Magnetic Analysis

2018-01-04844/3/2018

Rotor Clutch sub-assembly is one of the very important sub-assemblies (S/A) of an automotive compressor as it delivers the required torque/power to run the compressor. It mainly consists of rotor and bearing, stator, hub and armature. Rotor is rotated by engine pulley through belt drive system, while stator housing has got number of coils winded around stator slot. The hub sub-assembly is attached to the compressor shaft via spline arrangement and bolted across. When direct current (DC) is supplied to the terminal of the rotor, an electromagnetic field is generated which causes to attract the hub part towards rotor. Once the hub and rotor gets engaged each other, torque is transmitted to the compressor shaft which then helps to complete the suction and compression of refrigerant gas and thus making the vapor cycle run to produce adequate cooling in the air-conditioning (AC) system. Hence it is most important to ensure adequate and even distribution of electromagnetic field which is solely responsible for providing torque to the compressor. The present paper describes the numerical simulation of electromagnetic field of a clutch sub-assembly of an automotive compressor. ANSYS software was used to simulate the same. 2dimensional geometry of clutch rotor sub-assembly was created from computer aided design (CAD) tool and imported in suitable format. Meshing was performed using shell elements and the necessary material properties like permeability and B-H curve were defined along with the load conditions. The obtained flux density was then optimized by changing the shape and size of clutch sub-assembly. Further to this shaft torque was calculated analytically using the numerically obtained flux density and validated with the required torque for compression/suction process. The validation results exhibit a good trend and correlation, thus helping to develop a procedure to design clutch sub-assembly ‘first time right’ at the design stage. It is also ensured by this to have adequate torque delivered to the compressor.

Meena, Avadhesh, Sen, Somnath

Flow Visualization and Experimental Measurement of Compressor Oil Separator

2018-01-0067

4/3/2018

This article presents basic separation mechanisms with coalescing/impinging separators studied as the add-on to current popular centrifugal designs. The coalescence and impingement of oil on wire mesh and wave-plates are visualized and tested to investigate the impact of geometry and flow conditions on oil separation efficiency. Re-entrainment phenomenon is explained based on the mass balance. Oil mist flow at the swashplate reciprocating compressor discharge is quantified by video processing method to provide detailed information of the oil droplets. The physics behind oil separator is illustrated by visualization and measurement in this study, which gives useful guidelines for oil separator design and operation. The flow visualization shows the details of oil passing through different oil separation structures. Videos are quantified to provide information like droplet size distribution and liquid volume fraction. Experimental measurement shows that effective separation efficiency decreases when vapor velocity goes up. This is because higher vapor velocity brings higher liquid volume fraction and smaller droplets and higher vapor velocity will makes more trapped oil re-entrained.

Xu, Jiu, Hrnjak, Pega

Experimental Investigation on Surge Phenomena in an Automotive Turbocharger Compressor

2018-01-09764/3/2018

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

Optimization of the Engine Intake Air Temperature through the Air Conditioning Unit

2018-01-09734/3/2018

In modern turbocharged internal combustion engines the cooling of the air after the compression stage is the standard technique to reduce temperature of the engine intake air aimed at improving cylinder filling (volumetric efficiency) and, therefore, overall global efficiency. At present, standard values for the intake air temperature are in the range 30-70°C, dependently on engine load, external air conditions and vehicle speed and the adoption of a dedicated cooling fluid operating at low temperatures (-10-0°C) is addressed as the most viable option to achieve an effective temperature reduction. This paper investigates a pilot engine set-up, featuring an evaporator on the intake line of a turbocharged diesel engine, tested on a high speed dynamometer bench: the evaporator was a part of an air refrigeration unit – the same used for cabin cooling - composed also by a compressor, a condenser and a thermostatic expansion valve. The effects of the undercooling of the charge air have been experimentally assessed in terms of fuel consumption and regulated emission reduction, evaluated on the most common engine operating points. Mechanical power needed by the compressor was obviously taken into account in order to assess the overall benefits. A fuel consumption reduction has been demonstrated in the order of 2.5% when the intake air subcooling is turned on. A benefit on the regulated emissions has been observed (NOx, PM). HC and CO behavior, on the contrary, deserves some more attention and involves engine control parameters (for instance, EGR rate) and combustion performances.

Di Battista, Davide, Vittorini, Diego, Di Bartolomeo, Marco, Cipollone, Roberto

Air Dryer Installation Procedure

J2383_201711 (Historical)11/15/2017

Truck and Bus Brake Supply and Control Components Committee

Study on Nonlinear Rotordynamics Characteristics for Electric Compound Turbocharger

2017-01-241810/8/2017

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

A Comparison of On-Engine Surge Detection Algorithms using Knock Accelerometers

2017-01-242010/8/2017

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

The Effect of Ported Shroud Recirculating Casing Treatment on Turbocharger Centrifugal Compressor Acoustics

2017-01-17966/5/2017

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

Ejector Energy-Saving Technology for Mobile Air Conditioning Systems

2017-01-01203/28/2017

This study reports on a new generation ECS (Ejector Cycle System) which includes a highly efficient ejector and a novel system configuration. The ejector is working as a fluid jet pump that recovers expansion energy which is wasted in the conventional refrigeration cycle decompression process, and converts the recovered expansion energy into pressure energy and raises the compressor suction pressure. Consequently, the ejector system can reduce power consumption of the compressor by using the above mentioned pressure-rising effect and improve energy efficiency of the refrigeration cycle. The ejector consists of a nozzle, a suction section, a mixing section and a diffuser. The objective of this study is to improve actual fuel economy of all vehicles by ejector technology. The previous generation ECS was reported in 2012 SAE World Congress1. Now, a new generation ECS has been successfully developed and released in the market for Mobile Air Conditioning systems as of 2013. It achieves higher energy efficiency through the development of ARC (Active flow Ratio Control. It means to control the refrigerant flow ratio of the suction flow to the total flow by separating gas-liquid two phase flow), improved design of each ejector part, and improved internal flow distribution inside the evaporator. The ejector is integrated into the tank of evaporator like the previous generation, so there is no impact to vehicle packaging space. Test results demonstrated that the new generation ECS reduced annual power consumption of compressor by 10% compared to previous generation and by 20% compared to conventional expansion valve systems. The new generation ejector technology can significantly improve actual fuel consumption of Mobile Air Conditioning systems and contribute to global greenhouse gas reduction.

Shan, Zhiwei, Kawamoto, Yoichiro, Ogata, Gota

Development of the Large Type Electric-Driven Refrigerator for the HV Truck

2017-01-01373/28/2017

In respect to the present large refrigerator trucks, sub-engine type is the main product, but the basic structure does not change greatly since the introduction for around 50 years. A sub-engine type uses an industrial engine to drive the compressor, and the environmental correspondence such as the fuel consumption, the emission is late remarkably. In addition, most of trucks carry the truck equipment including the refrigerator which consumes fuel about 20% of whole vehicle. Focusing on this point, the following are the reports about the system development plan for fuel consumption reduction of the large size refrigerator truck. New concept is to utilize electrical power from HV system to power the electric-driven refrigerator. We have developed a fully electric-driven refrigerator system, which uses regenerated energy that is dedicated for our refrigerator system. It is the world’s first new concept to use the all electricity that regenerated by HV system for the drive of our electric refrigerator, not only for a run assist. Not limited to the high quality and stability refrigerator performance, it also realizes the reduction of the fuel and noise during the freezing operation. Fuel consumption reduced due to light weight drive system by replacing the heavy sub-engine to an electric compressor and also elimination of additional fuel line for sub-engine. Also, the maintenance expense can decrease because of the simple drive system and piping layout. By the all-in-one unit structure which is integrated an electric compressor close to the evaporator and condenser, the refrigerant piping is largely shortened and the efficiency and the reliability of the refrigerator are improved. We have proven that the system is able to save fuel consumption up to 64% by applying new control system which considers cooperation with the vehicle hybrid control system.

Ando, Akira, Hamashima, Koichi, Kato, Shinji, Tomita, Noriyuki, Uejima, Takahiro

Energy Consumption of Passenger Compartment Auxiliary Cooling System Based on Peltier Effect

2017-01-01553/28/2017

The closed cabin temperature is anticipated to be cooled down when it is a bit hot inside the driving car. The traditional air-condition lowers the cabin temperature by frequently switching the status of the compressor, which increases the engine’s parasitic power and shortens the compressor’s service-life. The semiconductor auxiliary cooling system with the properties of no moving parts, high control precision and quick response has the potential to assist the on-board air-condition in modulating the cabin temperature with relative small ranges. Little temperature differences between the cabin and the outside environment means that the system energy consumption to ensure the occupant comfort is relatively low and the inefficiency could be made up by the renewable energy source. This research focuses on the influence of the vehicle speed and the ambient temperature over the cooling energy consumption considering occupant heat dissipation in order to maximize the system energy utilization. Firstly, the occupant heat dissipation model is established and the system refrigerating capacity is confirmed for occupant comfort. Secondly, the temperature and the heat flux density at both ends of the semiconductor are studied. Finally, the energy consumption regulations of the auxiliary cooling system are clarified for different vehicle speeds and ambient temperatures. The results show that the vehicle speed is a key factor affecting the supplied current, especially for the vehicle speed less than 40km/h. The system current variation is within 0.4A corresponding to the ambient temperature changes. The occupant heat dissipation changes the current range. The system energy utilization could be improved by controlling the supplied current in a relatively small range at various vehicle speeds and ambient temperatures.

Xu, Yongbing, Tan, Gangfeng, Guo, Xuexun, Ping, Xianyao

Investigation of a Dual HVAC MAC System with Three Row Ducts Using 1D Modeling

2017-01-01643/28/2017

In an automotive air-conditioning (AC) system, upfront prediction of the cabin cool down rate in the initial design stage will help in reducing the overall product development (PD) time. Vehicle having higher seating capacity will have higher thermal load and providing thermal comfort to all passengers uniformly is a challenging task for the automotive HVAC (Heating Ventilation and Air conditioning) industry. Dual HVAC unit is generally used to provide uniform cooling to a large cabin volume. One dimensional (1D) simulation is being extensively used to predict the HVAC performance during the initial stage of PD. The refrigerant loop with components such as compressor, condenser, TXV and evaporator was modeled. The complicated vehicle cabin including the glazing surfaces and enclosures were modeled as a three row duct system using 1D tool AMESim®. The material type, density, specific heat capacity and thermal conductivity of the material were specified. The actual vehicle driving conditions as per test standard were used to validate the transient 1D HVAC performance simulations. The heat gain values of the panel ducts were adjusted to reduce the deviation from test. The simulated results for average cabin temperature and grill outlet temperature were compared against a surrogate vehicle test data. The detailed comparison of test data and simulation results were plotted and identified the simulation parameter which affects the correlation. Studies were carried out to understand the influence of thermal parameters on the performance of dual HVAC system and optimal values were arrived for the system under study.

Muthusamy, Venkatesan, Sathish Kumar, S., Sambandan, Saravanan

Effects of Thinner Condenser Technology on Vehicle AC Pull Down Performance

2017-01-01663/28/2017

The effects of substituting a 12 mm thick subcool on top condenser in place of a 16 mm subcool on bottom condenser are evaluated in a vehicle level AC pull down test. The A to B testing shows that a thinner condenser with subcool on top exhibits no degradation in AC performance while resulting in a lower total system refrigerant charge. The results are from vehicle level tests run in a climatically controlled vehicle level wind tunnel to simulate an AC pull down at 43°C ambient. In addition to cabin temperature and AC vent temperatures, comparison of compressor head pressures was also done. The conclusion of the study was that a standard 16 mm thick subcool on bottom IRD condenser can be replaced by a 12 mm thick subcool on top IRD condenser with no negative effects on performance.

Pandit, Noori

Heat Transfer Effect on Performance Map of a Turbocharger Turbine for Automotive Application

2017-01-10363/28/2017

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

Vibration Fatigue for Chassis-Mounted, Cantilevered Components

2017-01-03603/28/2017

Vehicle chassis mounted cantilevered components should meet two critical design targets: 1) NVH criterion to avoid resonance with road noise and engine vibration and 2) satisfied durability performance to avoid any incident in structure failure and dysfunction. Generally, two types of testing are performed to validate chassis mounted cantilevered component in the design process: shaker table testing and vehicle proving ground testing. Shaker table testing is a powered vibration endurance test performed with load input summarized from real proving ground data and accurate enough to replicate the physical test. The proving ground test is typically performed at critical milestones with full vehicles. Most tests are simplified lab testing to save cost and effort. CAE procedures that virtually replicate these lab tests is even more helpful in the design verification stages. A method for defining load input, Power Spectral Density or Sine Sweep, to predict the fatigue life of chassis component will be discussed. The CAE process for this topic, with an air suspension compressor support bracket as an example, is presented for vibration stress and fatigue as well as a process to predict and correlate a vibration shaker table key life test.

Song, Guangtian Gavin, Peters, Joe, Hopson, Steven, Jordan, Adrian

Optimal Pressure Based Detection of Compressor Instabilities Using the Hurst Exponent

2017-01-10403/28/2017

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

Control-Oriented Compressor Model with Adiabatic Efficiency Extrapolation

2017-01-10323/28/2017

Downsizing and turbocharging with single or multiple stages has been one of the main solutions to decrease fuel consumption and harmful exhaust emissions, while keeping a sufficient power output. An accurate and reliable control-oriented compressor model can be very helpful during the development phase, as well as for engine calibration, control design, diagnostic purposes or observer design. A complete compressor model consisting of mass flow and efficiency models is developed and motivated. The proposed model is not only able to represent accurately the normal region measured in a compressor map but also it is capable to extrapolate to low compressor speeds. Moreover, the efficiency extrapolation is studied by analyzing the known problem with heat transfer from the hot turbine side, which introduces errors in the measurements done in standard gas stands. Since the parameterization of the model is an important and necessary step in the modeling, a tailored parameterization approach is presented based on Total Least Squares. A standard compressor map is the only data required to parameterize the model. The parameterization is tested with a database of more than 230 compressor maps showing that it can deal well with different compressor sizes and characteristics. Also, general initialization values for the model parameters are provided using the complete database parameterization results. The results show that the model accuracy is good and in general achieves relative errors below one percent. A comparison of the model accuracy for compressor maps with and without heat transfer influence is carried out, showing a similar model accuracy for both cases but better when no heat transfer is present. Furthermore, it is shown that the model is capable to predict the efficiency characteristics at low speed of two compressor maps, measured with near adiabatic conditions.

Llamas, Xavier, Eriksson, Lars

Automated Calibration for Compressor Recirculation Valve Control

2017-01-05943/28/2017

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

A General Selection Method for the Compressor of the Hydrogen Internal Combustion Engine with Turbocharger

2017-01-10253/28/2017

Hydrogen is a promising energy carrier because it is characterized by a fast combustion velocity, a wide range of sources, and clean combustion products. A hydrogen internal combustion engine (H2ICE) with a turbocharger has been used to solve the contradiction of power density and control NOx. However, the selection of a H2ICE compressor with a turbocharger is very different from traditional engines because of gas fuel. Hydrogen as a gas fuel has the same volume as its cylinder and thus increases pressure and reduces the mass flow rate of air in cylinder for a port fuel injection-H2ICE (PFI-H2ICE). In this study, a general method involving a H2ICE with a turbocharger is proposed by considering the effect of hydrogen on cylinders. Using this method, we can calculate the turbocharged pressure ratio and mass flow rate of air based on the target power and general parameters. This method also provides a series of intake temperatures of air before calculation to improve accuracy. The calculated compressor outlet temperatures are compared with the theoretical temperatures to obtain accurate data. A fit compressor is selected for a 2.3 L H2ICE and the engine is tested at different engine speed and throttle openings to validate the correctness of this method. The error is below 5% when the experimental turbocharging pressure ratio and mass flow rate of air are compared with the calculated results, and this error is acceptable. Therefore, this method can be used as a basis for the designing and selection of H2ICE compressors.

Luo, Qinghe, Sun, Baigang, Wang, Xi

Thermodynamic Potential of Electrical Turbocharging for the Case of Small Passenger Car ICE under Steady Operation

2017-01-05263/28/2017

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

A Variable Displacement Supercharger Performance Evaluation

2017-01-06403/28/2017

The Variable Displacement Supercharger (VDS) is a twin helical screw style compressor that has a feature to change its displacement and its compression ratio actively during vehicle operation. This device can reduce the parasitic losses associated with supercharging and improve the relative fuel economy of a supercharged engine. Supercharging is a boosting choice with several advantages over turbocharging. There is fast pressure delivery to the engine intake manifold for fast engine torque response providing the fun to drive feel. The performance delivered by a supercharger can enable engine fuel economy actions to include engine downsizing and downspeeding. The cost and difficulty of engineering hot exhaust components is eliminated when using only an air side compressor. Faster catalyst warm up can be achieved when not warming the turbine housing of a turbocharger. To quantify these effects, a 2.0L Ford Eco-Boost® engine was chosen for an analytical comparison of three boosting configurations: turbocharged, roots style supercharged, and twin screw compressor supercharged with variable displacement. A number of partial load points were chosen to compare cycle averaged fuel consumption of the boost systems with weighting factors that represent a large SUV. Engine dynamometer testing validated the simulation results.

Wade, Robert, Murphy, Steven, Cross, Paul, Hansen, Craig

Comparative Small Engine Testing Using Hybrid Composite Cylinder Liners

2016-32-002211/8/2016

Cylinder liners exert a major influence on engine performance, reliability, durability and maintenance. Various combinations of nonmetallic reinforcements and coatings have been used to improve the tribological performance of sleeves or surfaces used in compressors and internal combustion engines in four stroke, two stroke and rotary configurations. In this paper we report the use of a hybrid composite containing silicon carbide and graphite in an aluminum alloy matrix to improve the performance of various small engines and compressors. Material properties of the base material, as well as comparative dynamometer testing, are presented.

Weiss, David, Beno, Simon, Jordan, Chris, Rohatgi, Pradeep

Characterization of Small-Scale Turbochargers for Unmanned Aerial Systems

2016-32-007811/8/2016

Aircraft engine power is degraded with increasing altitude according to the resultant reduction in air pressure, temperature, and density. One way to mitigate this problem is through turbo-normalization of the air being supplied to the engine. Supercharger and turbocharger components suffer from a well-recognized loss in efficiency as they are scaled down in order to match the reduced mass flow demands of small-scale Internal Combustion Engines. This is due in large part to problems related to machining tolerance limitations, such as the increase in relative operating clearances, and increased blade thickness relative to the flow area. As Internal Combustion Engines decrease in size, they also suffer from efficiency losses owing primarily to thermal loss. This amplifies the importance of maximizing the efficiency of all sub-systems in order to minimize specific fuel consumption and enhance overall aircraft performance. The lack of published performance data for many commercially sold superchargers in the mass flow range of concern for this study makes selection of efficient turbo-normalization systems very difficult. This paper will present an experimental procedure for characterizing turbomachinery components for several small-scale turbochargers and superchargers of interest for the target engine, which is a small-displacement Diesel engine. Data were derived from testing these machines on an experimental stand of the authors’ design. Compressor and turbine maps created from the resulting data are presented, along with the calculated adiabatic compressor efficiencies.

Mataczynski, Mark R., Litke, Paul, Naguy, Benjamin, Baranski, Jacob

Boosting Technologies and Limits for Small Combustion Engines

2016-32-007711/8/2016

Two-cylinder engines not only have special demands concerning uniformity and dynamics of oscillating masses and firing order, but also place very different demands on the turbocharger. With two-cylinder engines, the pulsating influence grows and changes the operation of the turbine. In this paper different boosting technologies are compared in small engine applications. Besides turbochargers the potentials and limits of superchargers and electric chargers are compared as well as their combinations. These technologies show differences concerning power supply, operation range and efficiency, and these effects have different implications in small engines. The efficiency of a turbo compressor, for example decreases, rapidly for small dimensions. Results from experiments and engine process simulations are shown based on a two-cylinder engine of 0.8l displacement. The operating condition of a turbocharger turbine in a two-cylinder engine is very specific due to exhaust pulsations. To understand this, a comparison was made with a four-cylinder engine based on numerical analyses. For the boundary conditions of the model, results of models from GT-Power simulations are used. Performing CFD-simulations, the turbine is driven by a two-and a four-cylinder-pulse, whereas both operations use the same specific exhaust enthalpy across one full engine cycle. In this regard, the pulsating operation of a small four-cylinder engine can be simulated and compared with those of a two-cylinder engine. The results show that for the optimization of a two-cylinder engine’s turbocharger, it is necessary to consider the specific pulse characteristics.

Baar, Roland, Boxberger, Valerius, Gern, Maike Sophie

Thermoeconomic Investigation of Different Gas Turbine Cycle Configurations for Marine Application

2016-01-222810/17/2016

Global energy scenario requires thermal systems with higher efficiency and lower capital and operating cost. The paper deals with the thermoeconomic analysis of the gas turbine cycles with possible application as marine gas turbines. Thermoeconomic analysis of an energy conversion cycle is a combined study of thermodynamics and economics. Different configurations of gas turbine cycles have been analyzed using thermo-economic methodology keeping the gas turbine operating parameters (compressor pressure ratio, turbine inlet temperature, isentropic efficiencies of compressor & turbine etc fixed. Study has been carried out by considering appropriate objective function in a form of decision variables. This objective function combines both fuel cost and investment cost. Correlation functions having variables such as pressure ratio, isentropic efficiencies of compressor & turbine and turbine inlet temperature have been presented for obtaining capital cost for all equipments of the cycle. The results obtained shows the plant cost (including equipment purchase cost, fuel cost, maintenance and investment cost) for proposed configurations of gas turbine cycles which may be useful to designers. The total cost flow rate for basic gas turbine (BGT), intercooled gas turbine (IcGT) and recuperated gas turbine (RcGT) has been found to be 0.37646 $/s, 0.40791$/s and 0.3518 $/s respectively.

Sahu, Mithilesh Kumar, Choudhary, Tushar, Sanjay, Y

Mitigating Impact of Bleed and Power Extraction with More Electric Architectures

2016-01-19919/20/2016

Aircraft subsystems essential for flight safety and airworthiness, including flight controls, environmental control system (ECS), anti-icing, electricity generation, and starting, require engine bleed and power extraction. Predictions of the resulting impacts on maximum altitude net thrust(>8%), range, and fuel burn, and quantification of turbofan performance sensitivities with compressor bleed, and with both high pressure(HP) rotor power extraction and low pressure(LP) rotor power extraction were obtained from simulation. These sensitivities indicated the judicious extraction options which would result in the least impact. The “No Bleed” system in Boeing 787 was a major step forward toward More Electric Aircraft (MEA) and analysis in this paper substantiates the claimed benefits. Also presented is the potential for future mitigation of impacts, including use of LP rotor power extraction for conserving both performance and compressor stall margin, increasing engine efficiency with on-line control effector perturbations, use of batteries for electric actuation of systems and taxiing, and identification of opportune engine operating conditions for charging batteries. Comparison is made between traditional architecture, Boeing’s “No Bleed” MEA and an envisioned future MEA. Discussion includes potential for further improvement in fuel burn, maintainability, and reliability with advanced MEA concepts which would reduce secondary power requirements. An additional objective was literature survey to learn from the excellent works of others. The nominal levels of both pneumatic and mechanical extractions for both traditional aircraft and MEA were derived from published literature. In future designs an integrated effort between engine and aircraft companies will be necessary to perform the required trade studies to determine improved architectures.

Khalid, Syed J.

Performance of a Custom Asymmetric Screw Compressor

2016-01-19969/20/2016

Modern military electronics systems are generating increasingly higher heat loads, necessitating larger capacity thermal management systems (TMSs). These high-capacity TMSs must meet the strict size and weight requirements of these advancing platforms. Commercially available compressor technology can generate sufficient cooling for these systems; however, they are too heavy and expansive. Mainstream Engineering Corporation has developed a compact, lightweight, high-speed screw compressor that can provide a large cooling capacity with a small package envelope. The compressor housing material is light-weight with a low coefficient of thermal expansion (CTE), allowing a wide operating temperature range. The compressor, with a nominal cooling capacity from 20 kW to 60 kW, was tested over a range of saturated suction conditions, pressure ratios, rotational speeds, and oil lubrication conditions. From this expansive data set, empirical correlations were generated for refrigerant mass flow rate, compressor power, and cooling capacity. The developed correlations agree strongly with tested data, validating measured compressor performance.

Markham, David R., Cutbirth, J. Michael

Power Density of Multi-Purpose Motor Controllers - Challenge Beyond Switches

2016-01-20129/20/2016

There are many identical large solid-state switching Multi-Purpose Motor Controllers on board of one of the More Electric Aircrafts (MEA). The controllers drive over twice as many different machines with wide torque and speed ranges. The common motor controllers are installed in a central location. The machines are located at diverse and distant positions. Power is delivered and routed from the controllers to machines via a large network comprising of unshielded feeders and multiplexing units. The controllers are required to produce sine wave voltage output to machines, and draw clean power from the source to meet Power Quality (PQ) and Electromagnetic Interference (EMI) requirements. There are significant aircraft level weight savings with that concept. However, designing such a clean motor controller was a major power density challenge beyond switches, accounting for high torque main propulsion engine start and high speed Cabin Air Compressors.

Feng, Frank, Pal, Debabrata

Improved Engine Health Monitoring Using Full Flight Data and Companion Engine Information

2016-01-20249/20/2016

Engine module performance trending and engine system anomaly detection and identification are core capabilities for any engine Condition Based Maintenance system. The genesis of on-condition monitoring can be traced back nearly 4 decades, and a methodology known as Gas Path Analysis (GPA) has played a pivotal role in its evolution. GPA is a general method that assesses and quantifies changes in the underlying performance of the major modules of the engine (compressors and turbines) which directly affect performance changes of interest such as fuel consumption, power availability, compressor surge margins, and the like. This approach has the added benefit in that it enables anomaly detection and identification of many engine system accessory faults (e.g., variable stator vanes, handling and customer bleeds, sensor biases and drift). Legacy GPA has been confined to off-board analysis of snapshot data averaged over a stable flight conditions when the engine is in steady state operation. This discrete data point approach, while fairly accurate and repeatable, comes with a price tag which is a time latency to detect (and subsequently isolate) a faulty condition. In this paper, we explore the use of streaming full flight data which includes both transient and steady state operation. This type of data stream, when properly processed, allows faster anomaly detection, credible fault persistency checks and timely fault identification. This paper outlines the use of companion engine data to achieve a cross-wing comparative diagnostic method.

Volponi, Allan J., Tang, Liang

Experimental Evaluation of an Automobile Air - Conditioning System with and without Liquid Suction Heat Exchanger

2016-01-91105/18/2016

Vaghela, Jignesh

Rotorcraft Turbine Engine Applications of Environetix's Wireless High Temperature Surface Acoustic Wave (SAW) Micro-Electromechanical Machines (MEM) Sensor System

F-0072-2016-11471

5/17/2016

The purpose of this paper is to explain the benefits, value, and achievements of Environetix's Surface Acoustic Wave (SAW) Micro-Electromechanical Machine (MEM) sensor technology, developed under the Army Small Business Innovative Research (SBIR) program, as an enabler for advanced monitoring of aircraft components for future Army sustainment efforts. Details will be provided to demonstrate how the SAW sensor system, with its micro-size, minimal weight, non-obtrusive characteristics, battery-free operation, and wireless transmission capabilities, can enable the autonomous monitoring of components/systems on Army rotorcraft. The details of the design, fabrication, and temperature sensing on an actual turbine engine compressor section will be presented. Finally, this paper recommends refining this technology and preparing it for validation/qualification testing in multiple Army turbine engines and other critical rotorcraft components.

Moffatt, John, Lad, Robert, Pereia, Maurice

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