扰流柱形状对冲击冷却综合换热效率影响研究

Numerical Simulation of Efficiency Index of Impingement Cooling System with Different Pin Fins Shapes

关键词:  冲击冷却  扰流柱  数值模拟  换热特性  流动特性  综合换热效率

Key words:  Impingement cooling  Pin fins  Numerical simulation  Heat transfer characteristic  Flow characteristic  Efficiency index

摘要:

为研究不同形状的扰流柱对冲击冷却系统的影响，对具有菱形、正方形、圆形以及椭圆形扰流柱的冲击冷却进行数值模拟研究，获得了射流Re在1×104～3×104内冲击靶板的换热特性以及通道内部流场的流动特征，分析冲击射流与不同形状的扰流柱之间的作用机理，并且为了综合考虑换热效果与流动阻力，使用综合换热效率来评价扰流柱在冲击冷却中的作用。研究结果表明:在冷却空气入口条件相同的情况下，菱形扰流柱靶板具有最高的平均努塞尔数[Nu]以及流动阻力，相比于正方形、圆形和椭圆形扰流柱，[Nu]分别提高了3.8%，8.9%，10.4%，流动阻力分别提高了9.6%，17.1%，21.3%。圆形扰流柱靶板的综合换热效率相比于菱形、正方形和椭圆形扰流柱分别提高了10.8%，4.9%，1.7%。扰流柱在冲击冷却中所起不同作用的主要原因是其与冲击射流作用后产生涡流的情况及其阻挡横流的能力。当综合考虑换热效果与流动阻力时，在所研究的4种扰流柱形状中，圆形扰流柱是最佳的选择。

Abstract:

In order to investigate the influence of impingement cooling system with different pin-fins， numerical simulation were conducted on impingement cooling with diamond， cubic， circular and elliptic pin fins to obtain the heat transfer characteristic and flow structure for the jet Reynolds ranging from 1×104 to 3×104， and the interaction between impinging jet and different pin-fins was analyzed. In order to consider the heat transfer and pressure loss together， efficiency index was used to evaluate the effect of pin fins in the impingement cooling system. The results show that the target plate with the diamond pin fins has the best heat transfer efficiency and the highest friction factor in the same cooling air inlet conditions. Comparing to the cubic， circular and elliptic pin fins， the overall averaged Nusselt number [Nu] of the target plate with diamond pin fins can increase by 3.8%， 8.9%， 10.4%， and the friction factor can increase by 9.6%， 17.1%， and 21.3%. The efficiency index of the target plate with circular pin fins can increase by 10.8%， 4.9%， 1.7%， comparing to the diamond， cubic and elliptic pin fins. The different effect between the impingement cooling with different pin-fins is mainly due to the situation of vortex generation and ability to reduce crossflow. Considering the trade-offs between heat transfer and friction factor， the circular pin fins can be the best choice among the shapes studied.