Characterization of thermal field in mixed-convection cooling of a flat plate by an impinging slot jet

摘要

This paper deals with the experimental and numerical study of cooling effect in low-speed two-dimensional slot jet impinging on an isothermal vertical hot plate. The jet is discharged into a semi confined zone which is bounded with two parallel isothermal walls. Both top and bottom boundaries are open to the ambient air. The wall adjacent to the nozzle is kept at the same temperature of ambient whereas the target surface is heated to maintain a constant temperature difference with respect to the opposite wall. The range of the jet Reynolds number on the basis of nozzle hydraulic diameter is kept within the range of 92 to 553. This leads to velocities of the same order of magnitude to that of natural convection close to the target wall. As an accurate optical method, Interferometry has been selected for experimental study of the thermal field behavior and for measuring the local heat transfer coefficient. A specific method of interferogram analysis for flat surfaces has been utilized for data reduction. Also the numerical simulation of the problem has been done for solving the flow field and for comparing the theoretical heat transfer model with the obtained experimental data. A commercial CFD package (FLUENT 6) has been utilized as a solver that uses finite volume method (FVM) to solve the governing equation of the problem. Variations of jet Reynolds numbers (Re), Nozzle to plate spacing (Z) and the nozzle vertical distance from the plate leading edge (Y) have been considered.