SLOT JET IMPINGEMENT HEAT TRANSFER ON FLAT AND RIBBED SURFACES FOR HIGH NOZZLE TO PLATE SPACING
A computational study was carried out for jet impingements over flat and ribbed surfaces to investigate heat transfer and flow characteristics for high nozzle to plate spacing using ANSYS Fluent 15.0 and OpenFOAM 4.1. Five RANS based turbulence models were used, namely, the standard k-ω, SST k-ω, standard k-ε, RNG k-ε and realizable k-ε turbulence model, and predictions were compared with the reported experimental and computational results. Various flow quantities, such as, distribution of turbulence kinetic energy and streamwise velocity, were also analyzed to obtain the physical insight of heat transfer enhancement with ribbed surfaces. A comparison of results obtained with ANSYS Fluent 15.0 and OpenFOAM 4.1 has also been presented. Further the effects of the rib to plate clearance and Reynolds number (Re) were investigated to understand the possible heat transfer enhancement. It is observed that the flow and heat transfer characteristics are significantly affected by the placement of detached ribs on the impingement surface compared to flat plate. With the detached rib configuration the augmentation in the local Nusselt number was observed in the region of clearances between rib to plate due to a sudden flow acceleration. However the stagnation point Nusselt number with the ribbed surface were found to be smaller compared to flat surface.