Comparative Calculation Study on Variable Geometry Exhaust Manifold Turbocharging System with Other Turbocharging Systems

In order to ensure the marine diesel engine has high performance at both high and low loads,a newly designed variable geometry exhaust manifold(VGEM) turbocharging system was put forward.The VGEM turbocharging system can realize switching between two charging modes by a controllable valve installed on the exhaust manifold.The one-dimensional steady simulation of VGEM turbocharging system was performed for an eight-cylinder marine diesel engine by using GT-POWER.According to the BSFC optimization the switching point is found to be at 50% load point.And then the simulations of the four-pulse,PC,MPC,and MIXPC turbocharging systems were conducted respectively for the diesel engine.The simulation results indicate that at all four loads of 25%、50%、75%、100%,the BSFC of the VGEM turbocharging system is always less than that of the four pulse,MPC,MIXPC turbocharging systems,and its average scavenging coefficient is always greater than that of other three systems.