Large eddy simulation of film cooling flow from a fanshaped hole

Large eddy simulation was applied for studying interaction between hot crossflow and coolant jet from a fanshaped hole. Simulations were performed at two blowing ratios, M = 0.5 and 1.5, and the Reynolds number, Re = 45674, based on the crossflow velocity and hole diameter. Downstream of shaped hole, plenty of hairpin vortexes distribute disorderly on the flat plate, and form 'forests of hairpin vortexes'. Roller vortexes and horseshoe vortexes are the important structures in the near filed region. Because of low jet velocity, fanshaped holes show weaker roller vortexes and horseshoe vortexes compared with round holes. In the far filed region, small-scale vortexes originating from break up of large-scale coherent structures take the dominant role. The projections of vortexes on vertical, spanwise and streamwise directions for fanshaped hole were discussed in detail. By time-frequency analysis of velocity fluctuation signals, the dominant frequency for fanshape holes is indistinct, and periodicity of film cooling of shaped holes is weaker than that of round hole. (C) 2017 Elsevier Ltd. All rights reserved.