Hydrothermal Analysis of Pulsed Jet Impinging on a Flat Surface with Different Pin Configurations

In this work, the effect of a pin as a secondary surface mounted on hydrothermal behavior of impinging jet over a flat plate investigated numerically and experimentally. The transient three-dimensional turbulent flow is simulated by the Renormalization Group (RNG) k − ɛ model. The injection air is pulsed by square waves. In a radial arrangement, several differently shaped pins (i.e., circular, elliptical, and square) with the same cross-sectional areas are compared. Within the experimental range, the results indicated that the use of a pulsating jet in the frequency range of 50-100 Hz enhances the rate of heat transfer. The rate of heat transfer of the square pin is less than that of the smooth surface. Based on specific performance parameters, the elliptical pin is found to be a favorable alternative configuration to a circular pin. Also, the results showed that the appropriate position to mount the pin on a flat surface at a radial distance is three times the diameter of the jet ( r=3D ) for elliptical and circular pins