气波增压柴油机排气管设计与试验

Design and Experimental Study for Exhaust Pipes of Pressure Wave Supercharged Diesel Engine

柴油机采用气波增压可有效降低NOx和烟度排放,匹配气波增压器的柴油机需重新设计排气管,除满足安装要求外,就是要保证进入气波增压器的排气压力稳定。设计侧向和中央出口渐扩式排气管,基于三维设计软件CATIA对这2种管进行几何建模及结构分析,确定满足气波增压要求的排气管结构,然后再基于流动分析软件ANSYS对这些试验管进行流动分析,综合考虑确定性能较好的排气管,加工出该管并进行台架实验。实验结果表明:采用该排气管的气波增压柴油机的动力和排放性能,在低转速下优于原机;在中等转速下接近原机;在高转速下比原机差。

NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging. The exhaust pipes in the diesel engine matched with pressure wave supercharger （PWS） need to be redesigned. The exhaust gas must be stable in pressure before rushing into the PWS, and the requirements for installation have to be met also. In this paper, the lateral and center ported divergent exhaust pipes are designed, modeled geometrically and analyzed structurally based on a 3D design software CATIA, to determine the structure of two exhaust pipes. The flow analysis for these two exhaust pipes is carried out using a flow analysis software ANSYS. The better exhaust pipe was determined synthetically and tested in bench. The test results show that PWS, comparing to turbo charging, is superior under low engine speed, close under medium speed and inferior under high speed in power and emission.