基于瞬态流动测量的柴油机扫气特性研究

Scavenging Characteristics of Diesel Engine Based on Transient Flow Measurement

为了准确研究某车用重型四冲程柴油机扫气特性,首先同步进行了进气歧管、气缸内、排气歧管内的瞬态流动的高精度测量,获得了进气压力-气缸压力-排气压力的准确波形。随后分析了该车用重型柴油机全工况下的扫气特性,以及由于扫气特性不良导致的内燃机性能恶化。为进一步优化该柴油机的扫气品质,进而优化该柴油机的性能参数,采用GT-Power软件建立了该柴油机的工作过程数值模型,并结合台架试验数据进行了模型的试验验证;随后基于排气压力波波形的控制需求,完成了排气歧管长度、排气歧管直径、排气歧管长度-直径组合方式、扫气相位等对柴油机扫气特性和进气能力的影响规律的研究,并基于影响规律完成了该重型柴油机的扫气性能优化,使缸内残余废气系数降低5.37%,柴油机全工况性能得到明显提升。

In order to research the scavenging characteristics of a heavy-duty 4-stroke diesel engine, the high-precision transient flow measurements in intake manifold, cylinder and exhaust manifold were first carried out, the accurate waveform of inlet pressure-cylinder pressure-exhaust pressure was obtained. Then the scavenging characteristics of heavy-duty diesel engine in all working conditions and the deterioration of internal combustion engine performance due to poor scavenging were analyzed. In order to further optimize the scavenging quality and the performance parameters of diesel engine, the numerical simulation of working process was established by GT-Power software, and the model was verified by test data. Based on the control requirements of exhaust pressure waveforms, the effects of exhaust manifold length, exhaust manifold diameter, combination of exhaust manifold length and diameter, and scavenging phase on scavenging characteristics and intake capacity of diesel engine were studied. Based on the influence law, the scavenging performance of heavy-duty diesel engine was optimized, the coefficient of residual gas decreased by 5.37%,and the all working performance improved obviously.