热机耦合作用下缸盖热状态影响因素研究
Research on Influence Factors of Cylinder Head Thermal State with Thermo-mechanical Coupling

为研究发动机缸盖在热机耦合作用下的热状态，利用流固耦合方法对缸盖的温度、耦合应力、热疲劳进行分析。然后，基于最优拉丁超立方法以及椭球基（EBF）神经网络模型建立燃烧强度、冷却液流动参数、机械载荷及火力面最高温度、最大耦合应力、低周热疲劳可用因子的近似模型，进行其影响因素的研究。分析结果表明：在燃烧强度的变量中，缸内温度和缸内换热系数对缸盖最大耦合应力以及热疲劳可用因子影响最大；提高冷却液进口温度，虽然降低了缸盖热疲劳可用因子但也升高了火力面最高温度，增大冷却液进口流速虽然降低了火力面最高温度但也升高了缸盖热疲劳可用因子；缸内最大爆发力对缸盖热疲劳可用因子、螺栓预紧力对缸盖最大耦合应力影响效果显著。
To study the engine cylinder head thermal state with the thermo-mechanical coupling, the temperature, the coupling stress and the cylinder head thermal fatigue were analyzed making use of fluid-structure interaction. Based on the Latin hypercube method, the elliptical basis functions neural network model was established to describe the relationship among the burning intensity, coolant flow parameters, mechanical load, the maximum coupling stress and the low-cyclic fatigue factor, and the main impact factors were studied. The results show that in the burning intensity the temperature and heat transfer coefficient of cylinder have a large impact on the maximum coupling stress and the low-cyclic fatigue factor. Improving the inlet temperature of coolant can decrease the low-cyclic fatigue factor, but increase the temperature of cylinder head. Improving the inlet flow of coolant can decrease the temperature of cylinder head, but increase the low-cyclic fatigue factor. The maximum explosive pressure has significant effect on the low-cyclic fatigue factor, and the stress pretension force has significant effect on the maximum coupling stress