The Study Of Matching And Design For Two-Stage Turbocharged Internal Combustion Engine

Downsizing the internal combustion engine (ICE) through turbochargingis an effective way to improve the fuel efficiency and reduce CO2emissions.In order to meet the demand of improving engine power, power recovery athigh altitude and improving EGR rate for ICE, two-stage turbocharging turnsout to be one of the key technologies of the advanced internal combustionengine. Matching of two-stage turbocharging is complicated and difficult.Traditionally, matching of turbocharging which is based on turbocharger MAPdata belongs to single-point design approach, in this method the turbochargerdesign is independent from the engine system development process, so it cannot improve the engine performance on all operation conditions.According to the key problem, a two-stage turbine through-flow designapproach was developed to improve the ICE’s overall performance. Theinfluence of two-stage turbine characteristics on turbocharged engine systemis discussed. The two-stage turbocharged I.C.E. through-flow matching anddesign platform is constructed. And the two-stage turbine through-flow designmethod based on the platform is discussed also. The thesis work containscontents as follows:The influence of two-stage turbine characteristics on ICE’s performanceon all operation conditions was investigated. The results show that thetwo-stage turbine off-design characteristics have great effect on engineperformance. Based on the inside flow mechanisms of radial turbine, athrough-flow model was introduced, and The two-stage turbocharged I.C.E.through-flow matching and design platform is constructed. Through thetwo-stage through-flow design platform, the influence of two-stage turbinegeometry parameters on ICE’s overall performance can be considered.Themodel was calibrated and validated with the test data. The influence oftwo-stage turbine geometrical parameters on ICE’s performance on alloperation conditions were discussed and it was found that five key parametershave the greatest influence on engine overall performance. Based on The two-stage turbocharged I.C.E. through-flow matching and design platform, atwo-stage turbine through-flow design approach was developed with theobjective of ICE’s performance for all operation conditions.The two-stage turbine through-flow design approach was successfullyapplied to a11L two-stage turbocharged diesel engine to develop a newtwo-stage turbine. Simulation results show that the diesel engine overallperformance has been improved obviously, especially on low-speed andlow-load conditions. the low-speed torque of the two-stage turbochargeddiesel engine matched with the new two-stage turbine has been increased by7.4%and rate of fuel consumption has been decreased by5.1%. Also, thecommon low-load condition fuel consumption has been decreased by5.2%.