Numerical investigation of an oscillating two dimensional rectangular impinging air jet

In this study, two infinite horizontal plates were considered. The bottom plate was kept at constant temperature, and the top plate was insulated. An oscillating air jet, issued from a rectangular slot on the top plate, was impinged on the bottom hot plate. The jet velocity oscillated sinusoidal. The jet Reynolds number was varied between 100 and 700. Oscillation amplitude and oscillation frequency were varied between 0.1V(o) - 0.5V(o) and 1-10 Hz, respectively. A computer program, based on control volume method and SIMPLE algorithm, was developed to numerically analyze the problem. Numerical simulations were performed to investigate effects of the Reynolds number, amplitude and frequency of the oscillation on flow and heat transfer. It was observed that maximum heat transfer rate is obtained on stagnation point and heat transfer rate decreases along the plate. The heat transfer rate increases at all points on the plate when Reynolds number increases. It was also observed that the stagnation point Nusselt number increases with increasing oscillation frequency and amplitude compared with steady jet Nusselt number. With increasing oscillation amplitude and frequency the Nusselt number increases 4.51% for Re=100, 8.086% for Re=300, 11.061% for Re=500 and 13.944% for Re=700. Considering the impinging jets are used to increase the heat transfer rate locally, theses in the stagnation point Nusselt number are important.