Effect of Crossflow-to-Jet Temperature Ratio on Heat Transfer and Flow of Impingement Cooling

This paper studied an array impingement cooling with different temperature initial crossflow. Both the heat transfer and flow field of impingement cooling with four crossflow-to-jet temperature ratios (TR=1.0, 1.1, 1.2, 1.3) under four crossflow-to-jet mass flow ratios (CMFR=0.3, 0.5, 0.7, 0.9) and four jet Reynolds numbers (Rej=15,000, 25,000, 35,000, 45,000) are investigated. Results show that (1) as the Rej increases, the Nusselt number increases, but the friction loss coefficient decreases; (2) as the CMFR increases, Nusselt number and friction loss coefficient decrease; (3) as the TR increases, the Nusselt number always decreases, but the variation of friction loss coefficient is related to CMFR. To be specific, when the CMFR are 0.3 and 0.5, the friction loss coefficient decreases with the increase of TR, but when the CMFR are 0.7 and 0.9, it increases as the TR increases. The research results will clarify the effect mechanism of TR on impingement cooling.