Performance Study Of Automotive Diesel Engines Equipped With VGT

As methods of enhancing engine power, improving fuel economy and emissions,turbocharger technology has been widely used on automotive diesel engines. But ordinaryturbocharger has many problems such as lack of low-speed torque, poor fuel economy onpartial load and turbo lag. In this case, variable geometry turbocharger (VGT) wasinvented. Because of complicated structure and flexible control method, it has a complexinfluence on diesel engines. For this, performance characteristics were studied inautomotive diesel engines equipped with VGT.The research object is a6-cylinder electronic control common rail turbochargeddiesel engine. Engine tests and VGT simulations were analyzed in this research includingsingle-stage and two-stage supercharge. Single-stage turbocharging tests measured boththe external characteristics and ESC-13working conditions, and based on the tests engineequipped with VGT and equipped with VGT&EGR were simulated and analyzed.Two-stage turbocharged engine, has been configured with EGR, tested ESC-13workingconditions, engine equipped with VGT were simulated and analyzed based on the tests.Experimental data and simulation results show that engine performance is improvedsignificantly when equipped with VGT. The external characteristic simulation results ofsingle-stage turbocharged engine equipped with VGT show that in medium engine speedarea power has greatly improved, the smaller degree of VGT increases torque at low speed,BSFC has been optimized at medium-low speed. ESC-13simulation shows that, enginedynamic performance largely improved while fuel economy can keep the original level.Single-stage supercharged engine equipped with VGT&EGR could get an ideal torqueand power, with certain of EGR rate. The simulation of two-stage turbocharged engineequipped with VGT indicates that engine dynamic performance can be improved comparewith the test engine, VGT still has a good effect on two-stage turbocharged engine.