Research On Matching Technology Of Variable Geometry Turbocharger And Diesel Engine

In recent years,turbocharger technology has been one of the key technologies in the field of internal combustion engines,and it has played an important role in improving the performance of internal combustion engines and reducing emissions.However,due to the nonadjustable boost pressure,insufficient torque during low speed,and poor fuel economy of conventional fixed-section turbocharger's,the variable geometry turbocharger technology has been studied and applied by researchers.This paper takes the GT2556 variable geometry turbocharger(VGT)and TBD314V8 diesel engine as the research object,and uses GT-Power to establish a variable geometry turbocharged diesel engine simulation model,performs a steady state performance matching study.First,a test is performed on the GT2556 variable geometry turbocharger,to measure the turbine flow and efficiency characteristics at various nozzle ring openings(100%,70%,50%,25% and 0%).The test provides a data foundation for the simulation of variable geometry turbocharger in GT-Power software;Secondly,according to the characteristics of the propeller of the diesel engine,the performance of the variable geometry turbocharger and the diesel engine are matched with.The regulation from the VGT opening variation on the diesel engine boost pressure and air flow are studied.The effects of VGT on the economy and dynamic property of diesel engines are analyzed.The results show that the VGT system improves the low-speed torque of the diesel engine and reduces the fuel consumption of the diesel engine.Finally,with the principle of economical optimization,the optimal VGT opening map is drawn.Finally,in order to explore the optimal exhaust systems of VGT diesel engine,the original pulsed turbocharged exhaust system of VGT diesel engine is modified.With GT-Power software,constant pressure exhaust system and MPC exhaust system are established.The simulation model of the air system is based on the characteristics of the standard propeller of a diesel engine,and a steady-state simulation calculation is carried out respectively.The main structural parameters of the exhaust system are optimized,and the influence of different exhaust systems on the main performance parameters of the dieselengine is analyzed.The results show that the utilization of constant pressure booster system,compared with the pulse booster system,improves the diesel engine torque at high load conditions of the diesel engine and reduces fuel consumption;but at low load conditions,the pulse booster system is better than constant booster system.With the MPC system,compared with the original pulse booster system,the diesel engine torque and power are increased and the fuel consumption is significantly reduced in the most of working conditions of the diesel engine.Comprehensively,if the diesel engine is working under high working conditions for a long time,the constant pressure booster exhaust system should be adopted,and economy and dynamic property are better;If better economic performance is required,the MPC booster system should be used;if better acceleration performance is required,the pulse booster systemshould be used.