Selecting And Matching For Two-stage Turbo System Of Diesel Engine

Turbocharging is the most effective measure to improve dynamic and economic performance of engine. With the continuous developement of diesel engine ,which has high power density as well as wide speed operation range, the matching requirements of diesel engine turbocharging system are increasing ,the turbocharging system evolves from single to two stage.Matching between engine and turbocharger is one of the most important work to do when selecting or before developing the turbocharger, but for the complicacy and diversity of two-stage turbocharging system, the matching method and calculating flow are not consummate, for this, this paper has programmed a turbocharging matching software called "TCMatch", which based on Visual C++,TCMatch can be easily used for the matching calculation of single-stage,wastegate,general two-stage,wastegate and the intake and exhaust bypass variable two-stage turbocharging system .Calculating method for matching of two-stage turbocharger has been researched in detail, and to improve calculating accuracy through re-selecting the engine exhaust temperature model , Using the testing datas of D6114,Yuchai 6M and 12V150 turbocharged diesel engine to check the single booster matching function on TCMatch, which taked the new exhaust temperature model, then proving the selection of exhaust temperature model is correct. After that, making the model of general two-stage and wastegate variable two-stage turbo system in GT-POWER, analysing the results of simulation with the two-stage turbocharing calcutaing function of TCMatch, resultly ,the errors were within 6%,verified that the calculating method of two-stage match was valid ,also TCMatch was available.Using the programmed software , we have researched different pressure ratio distribution's effect on matching result when calculating match point for general two-stage turbocharging,in result, as the pressure ratio distribution changes from 6:4 to 5:5 then 4:6,efficiency of turbocharger is increased,being away from surge, and proportion of high and low stage turbine nozzle area is tended to 2:3, which is close to the theoretical value when the total power is minimum;Have studied the match of intake and exhaust bypass two-stage turbocharger ,analysing the matching case of 12V190 ,a diesel used for ship with Miller circulation and two-stage turbocharger,in the extreme case of deep Miller cycle,through comparation and analysis of the datas, the intake and exhaust bypass makes the compressor's flow increase , low-condition part of the curve shift to the right ,and resolve the problem of compressor surge.