EFFECT OF NOZZLE - SURFACE SEPARATION DISTANCE ON IMPINGEMENT HEAT TRANSFER FOR A JET IN A CROSSFLOW.

Measurements were made of the local heat transfer coefficients resulting from the impingement of a turbulent jet which interacts with a crossflow. The experiments were performed for separation distances between the exit of the jet nozzle and the impingement surface ranging from 3 to 12 times the jet exit diameter. The ratio of jet to crossflow mass velocity was varied from 4 to 12. To evaluate the heat transfer coefficients, local recovery temperatures were also measured. The results for larger mass velocity ratios indicated that as the separation distance is varied, the impingement point heat transfer coefficient attains a maximum when the separation distance is 5-6 times the jet diameter. At a smaller mass velocity ratio such as 4, the maximum is attained at a substantially smaller separation distance.