中文摘要：

基于计算流体动力学（CFD）方法,分别采用带浮力修正的k-ε模型和P-1模型计算对流换热和热辐射,构建了包括LED固体部件和外部流体空间的全场三维数学模型。应用该模型对LED自然对流散热过程进行模拟,并通过物理试验验证了模型的有效性。计算表明,温度场与对流换热系数分布均具有各向异性特征,前者取决于芯片的功率密度和布设位置,而后者源于外部流体的流动状态。并且,辐射在整个散热过程中起着重要的作用,它不仅能减小热阻、降低结温,而且能弱化温度场的不均性、提高整体散热效率,在本文的计算条件下,辐射散热量占总散热功率的23.3%。

英文摘要：

Based on computational fluid dynamics（CFD） method,a full-field three-dimensional mathematical model of LED hardware and external fluid space are constructed and the natural convection and the radiation heat transfer are calculated by k-ε model with buoyancy correction and P-1 model,respectively.Simulations are carried out by this mathematical model and the obtained results are verified by physical experiments.The results show that the temperature field and the heat transfer coefficient are distributed anisotropically.The former is caused by the LED chip power density and spatial location,while the latter is resulted from the flow state of external fluid.Furthermore,the radiation plays an important role in the whole heat transfer process,which not only reduces thermal resistance and lowers LED junction temperature,but also weakens temperature field inhomogeneity and increases heat transfer efficiency.Under the calculational conditions in this paper,the radiaton heat transfer occupies 23.3% of the whole heat transfer.