Modification of Model Constants for Two Equations Turbulent Models in Impinging Jet Thermoflows

Abstract

Thermal jet streams are widely used in engineering. Turbulence models in thermal jet flows are also the subject of research in the literature. In impinging jet flow, the ratio of H (distance between nozzle exit and impact surface) and D_h (nozzle diameter) is of great importance. The Nusselt number is of great importance in terms of heat transfer. The size of the Nusselt number indicates the magnitude of the heat transfer. Therefore, it can be said that the heat transfer is higher when H/D_h is less than 5. Considering the experimental studies in the literature, the Nusselt number; It is seen that it depends on parameters such as Reynold number, Prandtl number, whether there is a limitation or not and turbulence. When we look at the numerical studies in the literature, the effect of the turbulence model and solution method used in addition to these parameters is also seen. In this article, the heat transfer phenomenon in the impact zone was observed computationally with the modified k-ɛ turbulence model on 4 impinging jet geometries with different boundary conditions using ANSYS FLUENT software and compared with the experimental studies in the literature. In this study, C_1ɛ and C_2ɛ coefficients used in the standard k-ɛ, RNG k-ɛ and Realizable k-ɛ turbulence models were changed, and the variation of the Nusselt coefficient along the impact plate was observed and compared with experimental studies. The reason for the mismatch of the k-ɛ turbulence model in the impinging jet flow is discussed.