Application of pressure and temperature sensitive paints for study of heat transfer to a circular impinging air jet

Experimental and computational studies are performed to study pressure and temperature distributions and flow patterns on impingement target surface subject to a single impinging air jet from a plenum. The experiments cover a range of jet-to-target plate distance, Z/D, from 1.5 to 12 for Reynolds number range from 10 000 to 60 000. The main objective is to investigate the optimal jet-to-target distance (Z/D) for stagnation point heat transfer and location of second peak in local heat transfer at small Z/D value under the current jet impingement configuration. Pressure and temperature sensitive paints measurements techniques are implemented to obtain the distribution of pressure and temperature on target surface. The optimal separation distance (Z/D) for stagnation region Nu is found to be about 5. The location of the second peak in local Nu for Z/D of 1.5 is at radial location (r/D) of about 1.8. The area averaged Nusselt numbers are compared to those calculated using correlation from open literature. The agreement varies with Z/D and jet Reynolds number. Experimental results are also compared to computational (CFD) prediction using realizable k-ε turbulence model.