可变几何排气管增压系统与其他增压系统的对比计算研究

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

为了解决某船用8缸机高低负荷兼顾的问题,提出了1种全新的可变几何排气管增压系统,它通过安装在排气管上的可控阀门来实现增压方式的转换。利用GT-POWER对可变几何排气管增压系统进行了计算研究,根据油耗最优原则找出其阀门开和阀门关之间的切换点在50%负荷;又分别对四脉冲增压系统、PC系统、MPC系统和MIXPC系统进行了计算研究。计算结果表明:在25%、50%、75%、100%负荷,可变几何排气管增压系统的油耗均小于四脉冲增压系统、MPC增压系统和MIXPC增压系统的油耗,扫气系数均大于四脉冲增压系统、MPC增压系统和MIXPC增压系统的扫气系数。

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.