Film cooling characteristics of a single round hole at various streamwise angles in a crossflow: Part II: heat transfer coefficients

Measurements of heat transfer coefficient (h) are presented for single jets with streamwise angles of 30°, 60° and 90° with a short but engine representative hole length (L/D=4). The freestream Reynolds number (ReD) is 8563, and the blowing ratio (M) ranges from 0.33 to 2. The results are presented in the form of h/h0 which is the ratio of heat transfer coefficient with film cooling to that without. Both local values and laterally averaged ones are presented, the latter refers to the averaged value across the central hole. The corresponding measurements of effectiveness are presented in a companion paper [C.H.N. Yuen, R.F. Martinez-Botas, Int. J. Heat Mass Transfer, Part I]. In general, only slight variations in h/h0 occurred as the blowing ratio was increased with the single 30° hole, in some contrast to the corresponding effectiveness measurements presented in the companion paper [Yuen and Martinez-Botas, Part I]. The single 60° and 90° jets yielded a smaller heat transfer coefficient than the 30° jet.