具有针肋的狭窄空间冲击冷却实验和数值计算

Experiment and numerical computation of impingement cooling in narrow space with pin fins

对具有全高度针肋扰流的狭窄空间冲击冷却进行了实验和数值计算,并与平板靶板冲击冷却传热性能进行了对比分析.射流冲击雷诺数范围为15 000~30 000.实验采用瞬态液晶热像技术获得了冲击靶板上详细的传热分布,并通过数值计算获得了冲击冷却系统中的流场和传热特征.实验研究表明：狭窄空间冲击冷却中的针肋靶板端壁上的平均传热性能比平板靶板提高约7.0%,压力损失提高约17.9%,并且针肋改善了靶板端壁上传热均匀性.另一方面,数值计算分析表明近壁面射流以及空间中的上洗涡流与针肋表面发生强烈相互作用,并且针肋显著地增加了换热面积,因此具有针肋扰流的冲击冷却系统具有显著增强的总体传热性能,比平板冲击冷却提高约27.0%.

Experimental and numerical computation were conducted on impingement cooling in a narrow space with full-height pin fins turbulated flow, and the performance comparisons were made with another impingement cooling on the flat target plate under maximum cross flow scheme. The jet Reynolds number ranges from 15 000 to 30 000. Transient liquid crystal thermography method was used in the experiments to obtain the detailed impingement heat transfer distribution on the endwall of the target plates, and nu- merical computation was done to examine the flow structure and heat transfer characteristics in the impingement cooling systems. Experimental study shows that the pin-fin can slightly improve the average heat transfer characteristics on the endwall of the target plate by about 7.0 %, and increase the pressure loss by about 17.9 %. It is also found that heat transfer uniformity is also improved on the endwall of the target plate with pin fin. On the other hand, numerical computations still show that the wall jets and the upwashing vortex in the space strongly interact with the pin fins, and the pin fins appreciably increase the heat transfer area, therefore the impingement cooling system with pin fins has significantly improved the total heat transfer performance by about 27. 0 % compared with the impingement with the flat plate.