Abstract: Exhaust manifold is one of the necessary parts of the engine, which has a great impact on the performance of the engine. In this paper, the bent pipe of exhaust manifold is studied, the theoretical model of gas flow in the bent pipe is established, and the gas flow condition in the bent pipe is simulated by FLUENT software. Then the gas in two kinds of curved pipes (90°-56°pipe and 90°-90°pipe) is compared and analyzed. The results show that the gas velocity distribution, pressure distribution and flow line distribution in the 90°-90°pipeline are more uniform, the flow separation area and eddy current are relatively small, and the velocity uniformity coefficient is closer to one, which has less influence on the diesel engine intake and gives full play to the dynamic performance of the diesel engine.

Key words: Exhaust manifold; Bending pipes; Turbulence model; Flow field analysis

摘要： 排气歧管是发动机的必要零部件之一，对发动机的性能有很大的影响。文章对排气歧 管的弯曲管进行了研究，建立了弯管内气体流动的理论模型，利用 FLUENT 软件对弯管内气 体流动状况进行了仿真，然后对两种弯曲管道（90°-56°管和 90°-90°管）中的气体进行 了对比分析。结果表明，90°-90°管道内的气体速度分布、压力分布和流线分布更为均匀， 流动分离面积和涡流相对较小，速度均匀系数更接近于 1，对柴油机进气的影响较小，柴油 机的动力性能得以充分发挥。

关键词: 排气歧管；弯曲管道；湍流模型；流场分析