Prediction of turbulent heat transfer in impinging jet geometries

This chapter summarizes the current knowledge on the numerical prediction of turbulent impinging jet flows. The predictive capabilities of numerical models are evaluated by careful comparison with experimental fluid flow and heat transfer data. Turbulent fluctuations in the velocity field are mathematically modelled using the Reynolds Averaged Navier–Stokes (RANS) methodology. Turbulence is assumed to be isotropic so only RANS models based on the eddy viscosity concept will be considered. Wall effects were approximated using various methods such as the elliptic relaxation methodology proposed by Durbin [1], the two-layer approach of Chen and Patel [2] and the low-Reynolds-number treatment of Launder and Sharma [3]. Important parameters influencing the accuracy of numerical predictions are addressed. In particular, the sensitivity of the predicted data to boundary conditions are highlighted to stress the importance of specifying the correct boundary conditions in the simulations. Predicted data from numerical simulations of the axisymmetric round jet impinging normally on a flat surface and three-dimensional round jet impinging at an angle to a flat plate with numerous jetto-plate distances and various oblique angles are presented. Data from these calculations are used to highlight modelling issues pertaining to entrainment, streamline curvature and heat transfer in the stagnation region of the flow. For the axisymmetric normal jet case, predicted data from a confined jet and jet impingement on a pedestal are also presented. www.witpress.com, ISSN 1755-8336 (on-line) WIT Transactions on State of the Art in Science and Engineering, Vol 15, © 2005 WIT Press doi:10.2495/978-1-85312-956-8/05