Turbulence and Vorticity Effects on Stagnation Region Heat Transfer

An experimental study has been performed to investigate the influences of freestream turbulence, including the vorticity field, on the stagnation region heat transfer. A heat transfer model with a cylindrical leading edge was tested in a low speed wind tunnel at Reynolds numbers ranging from 67,750 to 142,250 based on leading edge diameter of the model. Grids of parallel rods were used to generate the freestream turbulence with well-defined primary vortex lines. The grids were placed at several locations upstream of the heat transfer model in orientations where the rods were perpendicular and parallel to the stagnation line. The turbulence intensity and the ratio of integral length scale to leading edge diameter were in the range of 3.93 to 11.78 % and 0.07 to 0.7, respectively. The measured heat transfer data and freestream turbulence characteristics are compared with existing correlation models. A new correlation for the stagnation line heat transfer has been developed that includes the spanwise fluctuating vorticity components.