Numerical investigation of the heat transfer and flow field of a generic impingement jet cooling configuration

Abstract

This work deals with the numerical investigation of a generic impingement jet cooling system. The findings are used to complement a corresponding experimental investigation of a generic impingement jet cooling geometry. The investigated geometry consists of nine jets in a cross-flow impinging on a flat smooth target plate. The jet holes have a diameter D=10mm, the separation distance is H=D=4 and the jet-to-jet spacing X=D=5. Two jet Reynolds number are studied, Re=10000 and Re=35000. An extensive literature review was performed, with a focus on recent articles. The simulations are run with the DLR inhouse Computational Fluid Dynamics (CFD) solver Turbomachinery Research Aerodynamic Computational Environment (TRACE). The numerical approach uses the Reynolds-averaged Navier-Stokes (RANS) method and the Menter Shear Stress Transport (SST) k −! turbulence model with the low Reynolds approach to solve the boundary layer. The target plate is heated with a heat flux q=8000W/m^2 and all the others walls are adiabatic. Finally, a Grid Convergence Index (GCI) study is realized to ensure a mesh independent solution. Velocity, vorticity, turbulent kinetic energy and temperature fields are compared and discussed, as well as Nusselt number distribution. It has been found that TRACE is able to predict well the flow field of a generic impingement jet cooling configuration, as the findings agree with the literature. However, the averaged Nusselt number is overpredicted by 31% compared to experimental results because of an overproduction of turbulences at the stagnation points made by the turbulence model. Once the Nusselt number normalized, the results are much more suitable as the heat transfer is underpredicted by only 9% at the stagnation points, and is similar at the second stagnation points.