Flow and heat transfer characteristics of a return-flow impingement cooling scheme with varied target surface curvature for turbine blade leading edge

The effect of target surface curvature on flow field and heat transfer performance of a return-flow impingement cooling structure is investigated numerically by the BSL turbulence model in this study. Seven cases are presented and the jet Reynolds number is set as 5,000, 10,000 and 15,000 in each case. The effects of sidewall are considered so that the results are more convincing. The results indicate that the increase of target surface curvature further suppresses the crossflow in the impingement channel and contributes to the scraping effect of the swirling flow in return channel, which improves the intensity and the uniformity of overall heat transfer performance. The average Nusselt number in the impingement channel is increased by 16.6%-21.4% while that in the return channel is increased by 26.4%-30.0%, comparing the case with the highest target surface curvature and the case with flat target surface.