Experimental study on heat transfer enhancement of square-array jet impingement by using an integrated synthetic jet actuator

A novel concept is proposed in the present study for improving the square-array jet impingement heat transfer by integrating a synthetic jet actuator into the array unit. To illustrate the potential of this concept, an experimental investigation is performed, wherein two jet Reynolds numbers ( Re = 3000 and 5000), three hole-to-hole pitches ( X/d = Y/d = 4, 5 and 6), and three impinging distances ( H/d =2,6 and 10) are considered while the synthetic jet is actuated at a fixed frequency of 180 Hz with a characteristic Reynolds number ( Re 0 ) of about 2430. The results show that the synthetic jet has rare influence on the stagnation heat transfer of square-array jet but effectively improves the local heat transfer at the central zone of array unit. Its potential is tightly dependent on the array layout, Reynolds number and impinging distance. In general, the spatially-averaged Nusselt number augment behaves more significantly for the situations with smaller jet Reynolds number and bigger impinging distance.