V型皱褶芯材夹层板对流换热性能评价及优化

The evaluation and the optimization of convective heat transfer performance of V-pattern folded core sandwich panels

为考察主动冷却式一体化热防护结构用V型皱褶芯材夹层结构的性能,文章采用Fluent软件模拟受恒定热流载荷皱褶芯材夹层板在强制对流条件下的传热过程,分析其换热特性和流道内流体流动规律;并在分析皱褶芯材夹层板中正三角和倒三角2种流道换热性能差异的基础上,提出相邻流道流向相反的改进方案。该方案可提高冷却剂的利用率,使结构温度分布更加均匀。相比于具有相同几何参数的波纹芯材夹层板,皱褶芯材夹层板具有更好的换热性能,但同时以更大的当量密度和进出口压降损失为代价。比较几种常用的热效率指标,并定义了一种同时考虑换热性能、泵功率和结构质量的热效率指标,再分别以不同的热效率指标为目标函数,对皱褶芯材的几何参数L、W和S进行初步优化设计。

To investigate the performance of sandwich structure with the V-pattern folded core used for integral thermal protection structure with active cooling,the heat transfer process in the sandwich structures with the folded cores under a constant heat flow loading is simulated by the computational fluid dynamics software Fluent during the forced convection,with analysis of the characteristics of the heat transfer and the flow pattern.The heat transfer performances of two kind of flow channels in the sandwich structure are compared,and an improved scheme of using the flow in the opposite direction of the adjacent flow channel is proposed to improve the utilization rate of the coolant and to make the temperature distribution in the structure more uniform.The active cooling effects of the folded-core sandwich panel and the corrugated-core sandwich panel are compared.Compared with the corrugated sandwich panel of the same geometric parameters,the corrugated sandwich panel enjoys a better heat transfer performance at the cost of a greater equivalent density and the inlet&outlet pressure drop loss.By comparing among several commonly-used thermal efficiency indexes,a new thermal efficiency index is defined with consideration of the heat transfer performance,the pump power and the structure weight.With different thermal efficiency indexes as the objective function,the geometrical parameters of the folded core such as L,W,S are optimized preliminarily.