ASSESSMENT OF TURBULENCE MODELS IN THE PREDICTION OF FLOW FIELD AND THERMAL CHARACTERISTICS OF WALL JET

Abstract

The present study deals with the assessment of different turbulence models for heated wall jet flow. The velocity field and thermal characteristics for isothermal and uniform heat flux surfaces in the presence of wall jet flow have been predicted using different turbulence models and the results are compared against the experimental data of Wygnanski et al. (1992), Schneider and Goldstein (1994), and AbdulNour et al. (2000). Thirteen different turbulence models are considered for validation, which include the Standard k- (SKE), Realizable k- (RKE), shear stress transport (SST), Sarkar & So (SSA), v 2 -f, Reynolds stress Model (RSM), and Spalart Allmaras (SA) models. Both standard wall function (swf) and enhanced wall treatment (ewt) options available in a commercial CFD solver have been used for near wall treatment for the high Reynolds number models. From the study, it is observed that only a few models could accurately predict the complex flow and thermal features of the heated wall jet. The near wall velocity profile captured using Realizable k- (RKE) with enhanced wall treatment (ewt) shows the best agreement with the experimental data as compared to the other models. Considerable deviation has been observed using SKE with standard wall function (swf) whereas the models of v 2 -f show good prediction of velocity and temperature profiles in the near field region. However, the v 2 -f model is found to deviate from the data in the downstream region where the velocity profiles exhibit similarity. In the prediction of heat transfer coefficient, RSM followed by SA and RKE with ewt, is found to be in closer agreement with the experimental data compared to the rest of the models. The computational time required for RSM is substantially higher than that of the other RANS models. Therefore, in the case of gas turbine combustor, since flow field is much more complex, the RKE with ewt would be the preferred choice over the SA model.