柴油机排气系统流通性能数值模拟及结构优化

针对4190ZLC船用中速柴油机燃油系统电控化改造项目,以该机排气系统为研究对象,以优化排气系统性能为目标,采用气道稳流试验和数值模拟相结合的方法对排气流动进行分析,发现结构不合理之处并进行优化。研究结果表明:原机排气道、排气阀座紧靠气缸的位置、气阀座和气阀等多处存在不合理的流动损失,其中排气道结构和排气阀座相对缸盖位置对流通性能影响较大;排气系统整体结构优化后,流量系数大幅提高,平均流量系数提高了16.71%,流动性能得到改善。

Numerical Simulation of the Flow Performance of a Diesel Engine Exhaust System and its Structural Optimization

In order to implement the electronic control reform project of a 4190ZLC marine medium speed diesel engine fuel injection system, the exhaust port steady flow test and numerical simulation were adopted to analyze the exhaust flow performance and optimize the structure of the exhaust system. Research shows that there are many unreasonable flow losses in the original exhaust system such as the exhaust port, the exhaust valve seat near the cylinder, the valve seat and valve. Among them the structure of the exhaust port and the position of the exhaust valve seat relative to the cylinder have a great influence on the flow performance. After optimization of the overall exhaust system structure, the flow coefficient has been greatly improved, which makes the average flow coefficient increased by 16.7%, thus greatly improving the flow performance of the exhaust system.