汽车发动机舱散热性能实验及数值研究

针对后置式汽车发动机舱过热问题,以某混合动力汽车为研究对象,运用3D/1D数值耦合方法,建立了发动机舱散热系统的耦合计算数值模型.通过耦合数值计算,对不同环境温度和车速条件下的机舱发动机部件表面对流换热系数、机舱空间流量系数进行了研究,总结了对流换热系数、流量系数的一般性规律,并拟合了相应的经验关系式,为发动机冷却系统一维模型以及发动机舱的设计研究提供了参数依据和理论基础.同时通过对机舱热流场分析,发现不同的机舱布置形式下,对流换热系数和机舱流场有明显影响.

Experimental and Numerical Study of the Cooling Performance of Automobile Engine Cabin

To cope with the problem of overheating of rear-mounted engine cabin,based on a type of hybrid vehicle,a coupled model for the cooling system of rear-mounted engine cabin was established by using the coupling 3D/1D model.Through the process of coupled calculation,the convection heat transfer coefficient of engine surfaces and the flow coefficient of engine cabin in different ambient temperatures and driving speeds were studied.In addition,the general laws of the heat transfer coefficient and the flow coefficient were summarized and empirical equations were provided.All the results proved basic parameters for the establishment of one-dimensional model and theoretical basis for the design of the engine cabin.By analyzing the heat flow field,it was found that convection heat transfer coefficient and flow field changed noticeably with different layouts of engine cabin.The increase of the area of ventilated grille in the rear of engine cabin or adjusting the layout of radiator reasonably can improve the uniformity of the heat flow field and enhance the capacity of convective heat transfer of engine surfaces.