Application of temperature and pressure sensitive paint to an obliquely impinging jet

Experiments are performed on sonic underexpanded and subsonic jets issuing from a converging nozzle and impinging on a flat plate at oblique incidence. Results are reported on two geometric configurations, jet impingement angles of 10 and 20 degrees at impingement distances of 3.8 and 4.5 jet diameters respectively. The jet velocity was varied from Mach 0.3 to Mach 1.0 while experimental measurements of surface temperature, pressure, and heat transfer coefficient are made using temperature and pressure sensitive paint. Surface measurements are complemented by schlieren flow visualization for the sonic test conditions. In each test configuration the location at which the heat transfer is a maximum is found upstream (in the direction of the nozzle) of the point of maximum pressure recovery and each point of maximum pressure/heat transfer is located upstream of the geometric impingement point (defined as the intersection of the jet axis and the impingement plate). In each case the location of the point of maximum pressure/heat transfer coefficient was found to be a function of impingement angle and impingement distance but independent of Reynolds number. The peak value of heat transfer is about 30% lower than the value predicted at the stagnation point of a normally impinging jet by laminar stagnation theory. The adiabatic wall temperature on the impingement surface is determined experimentally using temperaturesensitive paint.