A numerical study of heat transfer performance of oscillatory impinging jets

Enhancement of heat transfer to a planar surface by oscillating jets is presented in this work. Two jets from adjacent slots are made to oscillate with the same frequency but with a phase shift of pi/2. The two nozzles are idealisation of an array of oscillating jets. A two-dimensional model is developed using finite element methods to investigate the heat transfer performance with respect to the oscillation frequency, geometric parameters and the flows with Reynolds number in the range of 0 < Re <= 1200. The computational results show that the oscillatory flow jets achieve approximately 100% improvement of heat transfer efficiency over conventional steady flow jets. It is shown that the periodic disruption of the boundary layer leads to this improvement. Further, the analysis shows the existence of a range of frequencies that are effective depending on the separation between the nozzles. The study shows that frequencies as low as 1 Hz are effective depending on the nozzle separation. (c) 2008 Elsevier Ltd. All rights reserved.