分层结构孔隙内流动换热的格子Boltzmann模拟

Lattice Boltzmann Simulation of Flow Heat Transfer in Complex Pores with Hierarchical Structure

  • 摘要: 以发汗冷却技术为应用背景,基于D3Q19格子Boltzmann方法(LBM)研究分层结构多孔介质的孔隙构成和热物性参数对温度场的影响。采用球形颗粒堆积和随机生成方法对分层孔隙结构进行重构,并计算分析孔隙率、固体热导率、分层厚度占比和分层层数影响下的温度分布和传热特性。结果表明:沿流动方向的孔隙率越大,多孔介质固体的温升变化率越快;上疏下密结构孔隙内的固体温度比上密下疏结构低,而双层间的固体导热系数差越大,孔隙内的固体温度和变化率越低;相比于上密部分厚度占比越大的孔隙结构,上疏部分占比越小的孔隙内温度更低;分层结构不超过5层时,增加层数能降低换热介质温度,但层数大于5层时,孔隙介质的内部固体温度反而升高。

     

    Abstract: Based on the D3Q19 lattice Boltzmann method (LBM) and within the application context of transpiration cooling technology, this study investigates the influence of the pore structure and thermophysical parameters of a hierarchical porous medium on the temperature field. The layered pore structure is reconstructed using spherical particle packing and random generation methods. The temperature distribution and heat transfer characteristics under the effects of porosity, solid thermal conductivity, layer thickness ratio, and the number of layers are calculated and analyzed. The results show that a larger porosity along the flow direction leads to a faster temperature rise rate in the solid matrix of the porous medium. The solid temperature within pores of a structure with a sparse upper layer and a dense lower layer is lower than that of a structure with a dense upper layer and a sparse lower layer. Furthermore, a greater difference in the solid thermal conductivity between the two layers results in lower solid temperature and a slower rate of temperature change within the pores. Compared to a pore structure where the dense upper part constitutes a larger thickness proportion, a smaller proportion of the sparse upper part leads to a lower temperature within the pores. When the number of layers in the hierarchical structure does not exceed five, increasing the layer count can reduce the temperature of the heat exchange medium. However, when the number of layers exceeds five, the internal solid temperature of the porous medium increases instead.

     

/

返回文章
返回