Embed Size (px)
Citation preview
Results:A main aspect of the design of the turbocharger turbine is the choice of design point and the corresponding design parameters. As the designprocess is based on steady flow assumption but the flow imposed by the ICE is highly unsteady, the performance may be significantly different at”on-engine” conditions. A main governing parameter of the unsteadiness encountered by the turbine is the exhaust manifold volume andconfiguration. By scaling this volume for a Heavy-Duty engine, the impact on turbine operation is affected to a very large extent. With regards tothe steady flow design point parameters, lowering the exhaust manifold volume is moving turbine operation further away from this point.
For low exhaust manifold volumes, a highly loaded, low degree of reaction type of turbine might be a suitable choice in order to utilize theexhaust energy. The design space needed for this type of characteristics will point away from the common fully radial turbine.Further work will be focusing on the design aspect investigating the axial turbine type with regards to exhaust energy utilization, pulse separationand overall engine performance for Heavy-Duty engines.
Engineoptimizedturbinedesign
Turbocharging is a very common way of increasing both engine torque/power as well as improving engine efficiencyand is found on almost every modern engine. The focus of this project is turbocharger turbine design for Heavy-Dutyinternal combustion engines. The aim is to characterize the turbine operating conditions on engine and how to makebest use of the remaining energy present in the exhaust gases. This is investigated by considering different designstrategies for the turbine taking into account the pulsatile nature of the engine. Naturally this project is a part of theiHOT-side of CCGEX, but is also a collaboration between Scania CV AB and KTH.
Introduction and Motivation:
TheturbochargerisaverycommoncomponentonenginesusednowadaysbothforOttoandDieselcycleengines.Themaindriversareimprovedtorque/powerlevels,engineefficiency,possibilitytodownsizeetc.Theinherentunsteadinessoftheinternalcombustionengineisposingachallengeformatchingwithsteadyflowturbomachinerysuchasaturbochargerturbine.Onengineconditionsisbynomeanstheidealforsuchasteadyflowdevice.Byutilizingtheexhaustenergyfromtheenginecylinders,theturbinecandrivethecompressorprovidingboostpressureaswellasreducedorgaininpumpingwork.Theresultfromthisprojectcanimmediatelybecomeofuseforachievingbetterengineperformance,increasingpower/torquewhileimprovingefficiencyandemissions.
Setup:
The basic tools for this project is 1D engine simulation and 1D/3Dturbomachinery design software. The idea is to provide a processfrom an initial 1D turbine design to a fully defined, manufacturable3D prototype geometry for gas stand evaluation and/or enginetesting. In the design process, the geometry specification willevolve from 1D/3D evaluation using both turbomachinery andengine simulation.
Summary and Conclusion:The range of turbine operation is in most cases very wide forturbocharger turbines in Heavy-Duty engines. High exhaust energyutilization in order to gain high engine performance and efficiencyrequires a system based approach and understanding of the entireexhaust process of the ICE. For pulse-turbocharged engines withlow exhaust manifold volumes, radial turbomachinery is limitedwith regards to the efficiency and characteristics needed forefficient gas exchange. Axial type of turbines in this respect is aviable choice.
Acknowledgement:AcademicMainSupervisor:Prof. Dr. AndersChristiansen-Erlandsson,RoyalInstituteofTechnology,KTH
AcademicCo-Supervisor:Prof. Dr. MagnusGenrup,LundFacultyofEngineeringLTH
IndustrialSupervisor:ExpertEngineerMr.Per-IngeLarsson,ScaniaCVAB
TurbineEfficiencyHigh/LowExhaustManifoldVolume
P-VdiagramofaGeneralGasExchangeProcess,[1].
Meanline1DTurbineStage Simplified1DEngineModel
[1]TurbochargingtheInternalCombustionEngine,fig.1.6s.5,Watson&Janota,1982.
DesignPointParameters 3DGeometries
