Numerical simulation of an impinging jet array in a square channel covered by a porous layer

Abstract

In many heat transfer applications, the design of the flow field should warrant high heat transfer rates and, meanwhile, reduce the thermal stresses so that hot spots along the heat transfer surface be avoided. A combination of multiple jets impinging on a channel bed together with the surface covered by a porous layer is proposed to satisfy both objectives in the current study. A three-dimensional numerical simulation using a finite volume method with the second-order discretization has been applied to visualize the multiple-impinging jet flow behavior. The impacts of the porous medium parameters, including the thickness, permeability, and porosity, on the magnitude and distribution of the heat transfer along the channel bed have been evaluated. It is shown that the overall heat transfer performance of the proposed flow is significantly improved in comparison with the conventional case of the fluid flowing parallel to the channel bed. The presence of the porous layer leads to a more even spread of the fluid on the target surface, which reduces the thermal stresses and prevents the large differences between the highest and lowest values of heat transfer coefficients. They also found that both the porosity and particularly the permeability of the porous layer enhance the effect of the crossflow along the flow associated with the multiple-impinging jet setup. For a certain thickness of the porous layer, it is possible to reduce the amplitude of the Nusselt number oscillations effectively, while keeping the overall Nusselt number desirably high.