8170型柴油机应用可变几何排气管增压系统的计算研究

Calculation Study on the Variable Geometry Exhaust Manifold Turbo-charging System for the 8170 Diesel Engine

为了实现8缸柴油机高低负荷兼顾,提出新的可变几何排气管增压系统,通过安装在排气管上的可控阀门来实现增压方式的转换。对可变几何排气管增压系统进行稳态和瞬态计算研究。稳态计算结果表明,与原机MPC增压系统相比,在25%、50%、75%和100%负荷时,可变几何排气管增压系统的平均扫气系数均大于MPC系统的平均扫气系数,油耗均小于MPC增压系统的油耗。瞬态计算结果表明,可控阀门关闭以后,压气机后进气压力增加的程度较大。

In order to make the diesel engine can give a good performance both at the high load operation and the low load operation,a newly designed variable geometry exhaust manifold（VGEM） turbo-charging system was put forward for this engine.The VGEM turbo-charging system can realize the switch between two charging modes by the controllable valve.The simulations of the system in both steady state and transient state had been done.The steady simulation results indicated that in all 4 loads of 25%,50%,75% and 100%,the scavenging coefficient of the VGEM turbo-charging system is bigger than that of the MPC turbo-charging system,the BSFC of the VGEM turbocharging system is smaller than that of the MPC turbocharging system.The transient simulation results indicates that when the controllable valve is closed,the intake pressure after compressor increases more.