Performance analysis of different turbulence models in impinging jet cooling

The characteristics of heat transfer from a hot wall surface for the oblique impingement of a free turbulent slot jet have been investigated numerically. Different turbulent models — the k-ϵ, k-ω, SST k-ω, cubic k-ϵ and quadratic k-ϵ models — are used for the prediction of heat transfer and their results were compared with experimental results reported in the literature. The comparison shows that the k-ϵ, quadratic k-ϵ and SST k-ω models give more unsatisfactory results for the investigated configuration, while the cubic k-ϵ model is capable of predicting the local Nusselt number in wall-jet region only. The k-ω model exhibits the best agreement with the experimental results in both stagnation and wall-jet regions. Further, the k-ω model is applied to analyze the obliquely impinging jet heat transfer problem. The parametric effects of the jet inclination (ϕ=50∘, 70∘ and 90∘), jet-to-surface distance (dL=4, 6 and 8), Reynolds number (Re=12000, 15000 and 20000), and turbulent intensity (I=5%, 7.5% and 10%) have been presented. The heat transfer on the upward direction is seen to decrease, while that on the downward direction it rises for the increasing angle. It is to be noted that as the value of ϕ decreases, the point of maximum Nusselt number (Numax) displaces toward the upward direction from the geometric center point as well as its value reduces. The shifting of the Numax is found to be independent of Re and dL within the range considered for the study.