Jet impingement heat transfer on a flat plate at a constant wall temperature

Abstract

Gas-to-wall heat transfer configuration for a round air jet impinging on a circular flat plate is investigated experimentally to derive an average Nusselt number correlation. The impingement plate is placed at the bottom of a large adiabatic enclosure, and its temperature is imposed, by external circulation of a coolant. The simultaneous measurements of mass flow rate and characteristic temperatures (hot jet, cold wall, enclosure outlet) permit the determination of the average wall heat transfer coefficient, through an enthalpic balance of the enclosure. The jet Reynolds number, nozzle diameter D and nozzle-to-plate distance H are varied. These experimental measurements are compared with the results of a numerical CFD modelling. Simulations under constant wall heat flux conditions are compared to local Nusselt number distributions as given by the current literature, which validates the use of the Shear Stress Transport (SST) k – ω turbulence model for this problem. Simulated Nusselt numbers obtained at a constant wall temperature are found lower than under uniform heat flux conditions. Measurements and simulation results, at a constant wall temperature, are in good agreement. An average Nusselt number correlation is proposed for jet impingement heat transfer calculations under constant wall temperature conditions, as a function of the jet Reynolds number Re j ( 10 000 ⩽ Re j ⩽ 30 000 ) , the geometrical parameters R / D , H / D ( 3 ⩽ R / D ⩽ 10 ; 2 ⩽ H / D ⩽ 6 ), and the dimensionless viscosity ratio μ j / μ w ( 1.1 ⩽ μ j / μ w ⩽ 1.4 ) .