Film cooling characteristics of a single round hole at various streamwise angles in a crossflow: Part I effectiveness

Abstract

Film cooling effectiveness were studied experimentally on a cylindrical hole with a streamwise angle of 30°, 60° and 90°, in a flat plate test facility with a zero pressure gradient. The short but engine representative hole length ( L/ D=4) is constant for all three geometries. The blowing ratio ranges from 0.33 to 2, and the freestream Reynolds number based on the freestream velocity and hole diameter ( Re D) was 8563. Both local values and laterally averaged ones are presented, the latter refers to the averaged value across the central hole. The current results are compared with the experimental results obtained by other researchers, and the effects of variations in injection angle are described. There is not a single study on film cooling performance of a single round hole at the three streamwise angles for a wide range of blowing ratios with a short hole length. Therefore, the objective of the present study is to provide a consistent set of measurements in terms of effectiveness and heat transfer coefficients [Int. J. Heat Mass Transfer, 2002] obtained systematically on a flat plate, and to deliver a better understanding of film cooling performance, with explanations deduced from the existing knowledge of a single jet in crossflow, before more engine representative conditions are introduced. The present results also serve as a database for future numerical modelling.