微尺度阵列射流冲击结构换热特性实验研究

Experimental Investigation of Heat Transfer Characteristics

关键词:  微尺度  阵列冲击  换热系数  微尺度实验  克努森数  雷诺数

Key words:  Micro-scale  Jet impingement array  Heat transfer coefficient  Micro-scale experiment  Knudsen number  Reynolds

摘要:

为了研究真实发动机尺寸下带有长圆形扰流柱阵列射流冲击结构的换热特性，选取雷诺数Re范围为1000～10000，并保证与真实发动机工况相同的克努森数Kn条件下，进行了实验研究。扰流柱排布方式分为顺排和叉排，冲击孔径D=0.4mm，0.5mm，0.6mm，冲击距H/D=1，1.5，2，详细分析了几何参数对结构整体平均对流换热系数的影响。结果表明:扰流柱的排布方式对平均换热系数影响很小，原因在于长圆形扰流柱的导流作用强于扰流作用；相同雷诺数时，孔径减小，流量减小33%，换热系数最大下降幅度10%，小孔结构具有保持相同换热强度、减小流量的应用潜力；相同雷诺数时，换热系数随着冲击距的减小而增大。

Abstract:

In order to investigate the heat transfer characteristics of array jet impingement with oblong pin-fin in real engine size，experimental study was taken with the Reynolds number varying from 1000 to 10000 and the Knudsen number equal to the real working condition of engine. The arrangement of pin-fin arrays was divided into in-line and staggered. The diameter of impingement holes were 0.4mm，0.5mm and 0.6mm，respectively. Ratios of the distance between the impingement wall and the target wall to the impingement hole diameter(H/D)were 1，1.5 and 2，respectively. The effects of these geometries on the average heat transfer coefficient of the structure were studied. The results reveal that the arrangement of pin-fin arrays has little influence on average heat transfer coefficient of the channel. The oblong pin-fin is more likely to guide the flow than turbulent it .With the same Reynolds number when the impingement hole diameter decreases，the mass flow rate of the cooling-air decreases by 33%，but the average heat transfer coefficient drops 10% at most. The structure with smaller hole has the potential to keep the same heat transfer intensity and reduce the mass flow rate of the cooling-air at the same time. And with the same Reynolds number，the average heat transfer coefficient of the structure decreases as the H/D increases.