Study Of The Turbocharging System For Diesel Engine Operating At Varying Altitude Conditions

The altitude of the plateau in China is very high and varies greatly in a large range. The diesel engine operating at plateau not only faces the problem of performance reduction arising from the lack of inlet airflow, but also the problem of adapting the varying altitude. By means of turbocharging matching and fuel injection adjusting, the diesel engine can obtain power restoration at the matching altitude rather than every altitude. Matching with variable geometry turbocharger (VGT), the diesel engine can adapt itself to the varying air pressure and meet the boost demand at different operating altitudes.Based on the plateau corrected model of compressor and the through-flow model of fixed geometry turbine, a simulation model of the diesel engine is built, and is validated by the data from the plateau simulating experiment. The problems of the diesel engine operating at varying altitude conditions are analyzed by experiment and simulation.The variable geometry turbine through-flow model and the variable geometry turbocharged diesel engine model are built. Based on the variable geometry turbocharging matching law, a variable geometry turbine is designed and a compressor is chosen to meet the matching requirements of the diesel engine. The matching performance shows that the variable geometry turbocharged diesel engine can achieve the optimum power and fuel economy and ensure the turbocharger running reliably and safely at various altitudes.The self-adapted turbocharging system for diesel engine operating at varying altitude conditions is built based on the VGT. The steady and transient control strategies of the turbocharging system are studied to target the optimum power, fuel economy and transient response.