考虑主动散热圆柱多孔夹层材料等效热导率及散热性能

针对多孔夹层圆柱壳的主动散热性能以及等效热导率的计算问题，通过推导多孔结构的等效热导率和主动散热状态下的稳态温度控制方程，在对流换热条件下，计算了考虑主动散热后所折减的等效热导率，及其与结构相对密度和流体流速之间的关系。采用考虑主动散热的等效热导率，计算结构瞬态温度分布，并与有限元结果进行对比。同时，计算了夹层圆柱壳相对密度和结构散热性能的关系以及最大散热性能相对应的最优相对密度和最优杆件厚度。通过瞬态温度分布结果与有限元结果对比，得到采用考虑主动散热的等效热导率所得结果与有限元结果吻合，说明了计算等效热导率方法的有效性，并且可以准确地计算瞬态温度分布；同时分析得到等效热导率随着流体流速的增大而减小，随着结构相对密度的增大而增大；在相同结构质量下，正方形和正六边形构型具有较好的主动散热性能。

Effective thermal conductivity and heat dissipation performance of sandwich cylinder with cellular materials considering the active heat dissipation

For issues of active heat dissipation performance and effective thermal conductivity of the sandwich cylinder with cellular materials, the effective thermal conductivity including the effects of active heat dissipation of the sandwich cylinder was calculated, and its relationships with the relative density and the speed of the fluid were obtained by deriving the effective thermal conductivity and thermal governing equation under the heat convection boundary conditions. By considering the effective thermal conductivity of active heat dissipation, the transient temperature of the sandwich cylinder was calculated and compared with the result obtained by finite element method. Meanwhile, the relationship between the relative density and heat dissipation performance of the unit cells was obtained, and the optimal relative density and the optimal thickness corresponding to the maximum heat dissipation index in different dividing parts were also obtained. By comparing the transient temperature obtained by theoretical solutions using the effective thermal conductivity including the effects of active heat dissipation with FE simulations, the results are nearly the same, indicating the correct effective thermal conductivity and the accuracy to calculate the temperature of the structure. At the same time, the study demonstrates that the effective thermal conductivity increases with the decrease of the velocity of the fluid and the increase of the relative density of the structure. The Square and Hexagon have the best heat dissipation capability in the same mass quantity.