Numerical investigation of effect of semi-circular confinement bottom opening angle for slot jet impingement cooling on heated cylinder

摘要

A numerical analysis for the air slot jet impingement cooling of a heated circular cylinder with a semi-circular bottom opening confinement is carried out. The Reynolds number (Re-D) which is defined based on the cylinder diameter ranges from 30,000 to 90,000. The non-dimensional distance between the nozzle exit and the heated circular cylinder ranges from 4 to 10 and the bottom opening angle (alpha) for the semi-circular confinement ranges from 0 degrees - 120 degrees. The numerical results of the four turbulence models SST k-omega, realizable k-epsilon, RNG k-epsilon and v(2)f are compared to the experimental results. Further, the numerical results of the original and the modified v(2)f model are compared to the experimental results. From the comparison of the numerical and the experimental results, the SST k-omega model is found better from the other models for evaluating the fluid flow and the heat transfer characteristics. Hence, the further parametric investigation has been carried out by the SST k-omega model for h/S, Re-D and alpha. The mean Nusselt number (Nu(mD)) is found maximum at h/S = 4, 6, 8 and 10 for the value of the semi-circular confinement bottom opening angle alpha = 70 degrees, 60 degrees, 100 degrees and 90 degrees. The Reynolds number (Re-D) does not have much effect on the semi-circular confinement bottom opening angle (alpha) for the maximum value of the mean Nusselt number (Nu(mD)).