Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi - 110016, India
This paper presents results of a computational study to investigate the suitability of various RANS based turbulence models for slot jet impingement over flat and detached ribbed surfaces. The computed results are compared with the reported experimental data. It is observed that some turbulence models predict the experimental data with good trends, e.g., secondary peak in Nusselt number and distribution of normalized streamwise velocity. The standard k-ω and SST k-ω models predict heat transfer more accurately compared to that by other models with prediction of a secondary peak in Nusselt number. Distributions of turbulent kinetic energy, streamwise velocity and normal velocity are also analyzed to understand heat transfer behavior with flat and detached rib surfaces. Various parameters are considered to obtain a good understanding of heat transfer enhancement with jet impingement on a surface fitted with detached ribs. Further the effects of rib to plate clearance, position of first rib and Reynolds number on heat transfer characteristics are also investigated. It was observed that flow and heat transfer features are significantly affected by the placement of ribs on the impingement surface. Increasing the rib clearance, position of first rib in the streamwise direction and Reynolds number have favorable effects on heat transfer. The detached rib configuration offered augmentation in Nusselt number compared to the attached rib arrangement (i.e., with no clearance between the rib and impingement surface). Comparisons of stagnation point and average Nusselt numbers are also presented to understand heat transfer enhancement for flat and ribbed surfaces.