Numerical investigations of turbulent multiple jet impingement on a heated square block in a confined channel

Abstract

The analysis of fluid flow and heat transfer characteristics of turbulent single and multiple jets impinging on a square block in a confined channel has been studied numerically. The study of jet impingement on a square block is important as it is directly relevant to the cooling process of food products by jet impingement and present results would be useful in understanding this process. Two-dimensional unsteady state incompressible turbulent forced convection flow is considered for the present analysis. Turbulence is modelled by Reynolds Averaged Navier-Stokes (RANS) equation with a standard k-∊ model and enhanced wall treatment at the wall. The governing equations are solved using a finite volume-based commercial solver. The second-order upwind scheme is used for non-linear terms and the SIMPLE algorithm is used for the pressure-velocity decoupling problem. Effects of a single jet, double jet, 3 jets, and 4 jets, the center distance between jets, block size and height between the block and bottom jets on flow and heat transfer characteristics are reported. The better enhancement of heat transfer is observed from all surfaces of the block with multiple jet impingement compared with a single jet due to multiple recirculation zones than a single jet. The enhancement of heat transfer on the right surface of the block for 4 jets impingement is 113.3% compared to single jet impingement. The overall heat transfer rate is increased by 72.74% with an increase in center distance between jets from 2 to 6. Present results are validated with experimental results available in the literature.