考虑转捩的某高速船用汽油机排气管流固热耦合分析

Thermal Analysis of Fluid-solid Coupling of a High-Speed Marine Engine Exhaust Pipe Based on Transition

针对某高速船用汽油机原排气管在热冲击试验中的开裂问题,在增加排气管冷却水套的基础上,采用流固热耦合分析方法对排气管进行换热和热应力分析,并在此基础上,研究不同湍流模式和转捩对复杂流场流动与换热的影响。结果表明,不同湍流模型的温度计算结果和试验数据的吻合度均较好,证实了计算模型的准确性,而排气管的开裂系热应力过高所致,通过增加冷却水套可以解决排气管开裂问题;选用合适的湍流模型并考虑转捩影响,可以更加准确地判断分离点位置,提高复杂流场的数值模拟精度。

In view of the problem that the original exhaust manifold of a high speed marine gasoline engine is cracked in the thermal shock test. Based on the design of water jacket structure, the thermal analysis of fluid-solid coupling method is used in heat and thermal stress analysis is carried out on the exhaust pipe. On the basis of that, the impact of different turbulence model and transition on complex flow and heat transfer has been researched. The research result shows that the different turbulence calculation model is confirmed accurately, and the calculated temperature result and test data coincide well. Also exhaust pipe cracking is due to the thermal stress much high. Adding the cooling water jacket can solve the problem of exhaust manifold cracking. Selecting appropriate turbulence model and considering the influence of transition can more accurately determine the position of the separation point, and improve the numerical simulation precision of complex flow field.