Comparison between impingement/effusion and double swirl/effusion cooling performance under different effusion hole diameters

摘要

This paper numerically investigates the effects of the film cooling hole diameter on the flow and heat transfer characteristics of the impingement/effusion cooling and double swirl/effusion cooling. Impingement jet arrays at three jet Reynolds numbers, 10,000, 15,000, 20,000, are employed. The target channel consists of a semicircular channel in impingement/effusion cooling and two partially overlapping cylinders in double swirl/effusion cooling. Three arrays of film cooling hole rows are established on the target surface under two arrangements. Four film cooling hole diameters, 0.4, 0.6, 0.8 and 1.0 times the jet hole diameter, are considered. The flow structure and flow development inside the target channel are compared and analysed. The heat transfer performance are discussed and compared. Results show that the effusion air distribution and Nusselt number distribution is more uniform in double swirl/effusion cooling. With the application of the double swirl channel, about 20-33% increase in overall averaged Nusselt number of the whole target channel and about 12-20% increase in spatially averaged Nusselt number at the effective cooling region are obtained. With the application of the film cooling holes, the maximum increase in spatially averaged Nusselt number at the effective cooling region is 10.3% in impingement/effusion cooling and 4.7% in double swirl/effusion cooling. (C) 2019 Elsevier Ltd. All rights reserved.