柴油机排气歧管进气角度对排气性能影响

为研究柴油机排气系统的结构对增压方式及排气能量利用效率的影响,建立了某柴油机排气歧管的三维数值模型,采用动态控制技术,分析了各歧管联合排气时排气系统内的流动状态.结果表明,原始结构的排气管内存在漩涡、局部动态压力过大,排气歧管内气体流量分布最大不均匀度较大等现象.为提高排气性能,对排气歧管进气角度进行了优化.模拟结果表明,优化后涡流明显减少,局部动压降低2000 Pa,出口处最大不均匀度降低5.55％,该结构有利于排气.

Impact of Inlet Angle of Diesel Engine Exhaust Manifold on Exhaust Performance

In order to study the impact of the structure of exhaust system of diesel engine on the turbocharger and exhaust energy efficiency, a three dimensional numerical model of a diesel engine exhaust manifold was de- veloped. By using dynamic control technology, the dynamic internal flow of the exhaust system was analyzed. The results show that there are whirlpool and vortex, big local difference of dynamic pressure and uneven gas flux in different manifold in original exhaust system. It indicates that it is necessary to optimize the structure of the exhaust manifold to increase energy utilization ratio and working lifespan of the exhaust system. The opti- mized results show that the whirlpool and vortex and difference of dynamic pressure was reduced by 2 000 Pa and maximum uniformity of gas flux in different manifold is decreased by 5.55%. The optimized exhaust sys- tem is more conducive to exhaust.