مطالعه تاثير نيروهاي شناوري بر ضريب انتقال حرارت در برخورد جت آرام به صفحه با شار حرارتي ثابت

Buoyancy Effects in Laminar Slot Jet Impinging on a Surface with Constant Heat Flux

The two-dimensional laminar air jet issuing from a nozzle of half which terminates at height above a flat plate normal to the jet is numerically studied to determine the effects of buoyancy on the flow and thermal structure of the region near impingement. The impinging surface is maintained at a constant heat flux condition. The full Navier-Stokes and energy equations are solved by a finite difference method to evaluate the velocity profiles and temperature distribution. The governing parameters and their ranges are: Reynolds number Re, 10-50, Grashof number Gr, 0-50,Richardson number Ri = Gr/Re^2 , Non- dimensional nozzle height H, 2-3. Results of the free streamline, local friction factor and heat transfer coefficient are graphically presented. It is found that enhancement of the heat transfer rate is substantial for high Richardson number conditions. Although the laminar jet impingement for isothermal condition has been already studied, however the constant heat flux has not been studied enough. The present paper will analyze a low velocity air jet, which can be used for cooling of a simulated electronics package.