天然气发动机增压器匹配及试验验证

Matching and test verification of a natural gas engine turbocharger

在概念设计阶段,基于GT-Power软件建立某4缸天然气发动机的整机模型,该模型包括进气系统、缸内燃烧系统、废气再循环(excust gas recircluation,EGR)管路系统,根据工程经验,设置目标EGR率、点火提前角、燃烧持续期、燃烧重心为边界条件,仿真对比不同增压器方案的EGR率、EGR阀开启比例、燃气消耗率、增压器旁通阀放气比例、外特性联合运行线,结合工程应用中的增压器匹配原则,选出合适的增压器方案,并进行试验验证。试验结果表明:所选方案发动机的外特性联合运行线远离喘振线和堵塞区,中、高转速的运行点落在压气机高效区;标定点增压器转速余量大于18%,满足发动机性能要求。

In the conceptual design stage,based on GT-Power software,a complete simulation model of a four cylinder natural gas engine,including the intake system,combustion system in the cylinder,and EGR pipeline system,has been established.Based on engineering experience,target EGR rate,ignition advance angle,combustion duration,and combustion center is set as boundary conditions.The simulation compares the EGR rate,EGR valve opening ratio,gas consumption rate,turbocharger bypass valve bleeding ratio,and engine external operation line of different turbocharger schemes.According to the matching principle of turbocharger in engineering applications,a suitable turbocharger scheme is selected for experimental verification.The experimental results show that the combined operating line of the external characteristics of the selected scheme engine is far from the surge line and blockage zone,and the operating points of medium and high speeds fall in the high-efficiency zone of the compressor.The speed margin of the turbocharger at the designated point is greater than 18%,which meets the engine performance requirements.