微重力条件下列管相变蓄热器的传热特性研究及拓扑优化

基于相变蓄热器在航天航空领域的应用，对列管式蓄热器建立物理模型和数学模型，采用数值模拟研究其在不同重力及雷诺数下的传热特性，此外引入基于变密度法的拓扑优化方法对蓄热器进行结构优化，设计出一种不等长拓扑肋片模型，并对比研究各因素对相变材料熔化速度的影响。研究结果表明，相同雷诺数时微重力条件下相变材料的熔化速度相比于有重力条件下的较慢，不同雷诺数时微重力条件下的熔化速度比有重力条件下的熔化速度分别减小了82.7%,86.1%,90.1%。但在微重力条件下，增大雷诺数已不足以有效提升相变材料的熔化速度。与无肋片管相比，经拓扑优化所得肋片模型的强化换热效果明显，在微重力条件下其相变材料熔化时间相比于无肋片管熔化时间缩短了47.83%，表明所设计的拓扑优化肋片模型可有效地减小微重力对蓄/放热速率的影响。

Heat transfer characteristics and topology optimization of tubular phase change regenerator under microgravity

Based on the application of phase change thermal storage in the field of aerospace, physical and mathematic model of the tubular regenerator was built. Numerical simulation was adopted to study the heat transfer characteristics under different gravity and Reynolds number. A topology optimization method based on variable density method was introduced to optimize the structure of a regenerator. A long range topology fin model was designed, and the influence of various factors on the melting rate of phase change material (PCM) was compared. The results show that the melting rate of PCM under the same Reynolds number is slower than that under the gravity condition, and the melting rate under the different Reynolds number is 82.7%, 86.1% and 90.1% lower than that under the gravity condition, respectively. However, increasing Reynolds number is not enough to effectively improve the melting rate of PCM under microgravity conditions. Compared with the unfinned tube, the heat transfer enhancement effect of the fin model obtained by topology optimization is obvious, and the melting time of the phase change material is reduced by 47.83% compared with the melting time of the unfinned tube under microgravity condition, indicating that the topologically optimized fin model can effectively reduce the influence of microgravity on the heat storage and release rate.