Martin Elena, Valeije Alejandro, Sastre Francisco, Velazquez Angel
Departamento de Ingeniería Mecánica, Máquinas y Motores Térmicos y Fluidos, Escuela de Ingeniería Industrial, Campus Marcosende, Universidade de Vigo, 36310 Vigo, Spain.
Fluid Mechanics and Aerospace Propulsion Department, Universidad Politécnica de Madrid, Plaza del Cardenal Cisneros 3, 28040 Madrid, Spain.
Micromachines (Basel). 2022 Apr 12;13(4):599. doi: 10.3390/mi13040599.
A 3D numerical study is used to analyze the flow topology and performance, in terms of heat transfer efficiency and required pumping power, of heat sink devices with different channel aspect-ratio in the presence of tip-clearance. Seven different channel aspect ratios AR, from 0.25 to 1.75, were analyzed. The flow Reynolds numbers Re, based on the average velocity evaluated in the device channels region, were in the range of 200 to 1000. Two different behaviors of the global Nusselt were obtained depending on the flow Reynolds number: for Re<600, the heat transfer increased with the channels aspect ratio, e.g., for Re=400, the global Nusselt number increased by 14% for configuration AR=1.75 when compared to configuration AR=0.25. For Re>600, the maximum Nusselt is obtained for the squared-channel configuration, and, for some configurations, flow destabilization to a unsteady regime appeared. For Re=700, Nusselt number reduced when compared with the squared-channel device, 11% and 2% for configurations with AR=0.25 and 1.75, respectively. Dimensionless pressure drop decreased with the aspect ratio for all cases. In the context of micro-devices, where the Reynolds number is small, these results indicate that the use of channels with high aspect-ratios is more beneficial, both in terms of thermal and dynamic efficiency.
采用三维数值研究方法，分析了存在叶尖间隙时不同通道长宽比的散热器装置的流动拓扑结构和性能，包括传热效率和所需泵送功率。分析了七种不同的通道长宽比AR，范围从0.25到1.75。基于在装置通道区域评估的平均速度的流动雷诺数Re在200到1000范围内。根据流动雷诺数，获得了全局努塞尔数的两种不同行为：对于Re<600，传热随通道长宽比增加，例如，对于Re=400，与长宽比AR=0.25的配置相比，长宽比AR=1.75的配置的全局努塞尔数增加了14%。对于Re>600，方形通道配置获得最大努塞尔数，并且对于某些配置，出现了流向不稳定状态的情况。对于Re=700，与方形通道装置相比，长宽比AR=0.25和1.75的配置的努塞尔数分别降低了11%和2%。在所有情况下，无量纲压降均随长宽比降低。在雷诺数较小的微器件背景下，这些结果表明，使用高长宽比的通道在热效率和动态效率方面都更有益。
