Experimental and Numerical Study on Heat Transfer with Impinging Circular Jet on a Convex Hemispherical Surface

Abstract

In this paper, the experimental and numerical study has been carried out to investigate the water jet impingement on a convex hemispherical surface. The pressure and skin friction coefficient distributions on the impingement surface were analyzed numerically. A great deal of attention was paid to analyze the effects of the jet impingement exit velocity and the nozzle-tosurface distance on the heat transfer characteristics. A comparison of the heat transfer coefficient was performed between the jet impingement on the convex surface and the flat plate. The results show that the Nusselt number for the convex surface is higher than that for the flat surface. The local Nusselt number is decreased monotonically from its maximum value at the stagnation point for lower Reynolds numbers. A secondary maxima occurs for higher Reynolds numbers. The experiment and simulation were performed with the following parameters: the jet impingement Reynolds number of Re = 1947-19478, and the nozzle-to-surface distance of L/D = 2.5-25.

Mathematical modeling of the heat transfer and flow field of liquid refrigerants in a hydrofluidization system with a stationary sphere

“…After that, pressure is slightly recovered up to Cp % 0 for the remaining angles even after the separation point of the boundary layer. Similar profiles were observed in literature for systems with thin jet of air or water impinging on hemispherical (Lee et al, 1997;Hu and Zhang, 2007;Zhang et al, 2008) and flat (Baydar, 1999;Baydar and Ozmen, 2005) surfaces.…”

“…It is worth mentioning that very few articles related to the experimental study of liquid-jet impinging on a spherical surface have been published mainly due to obstacles such as high heat-generating rate and difficulty for the measurement comparisons with a gas jet (Hu and Zhang, 2007). The situation is even more complicated for systems with liquid submerged jets impinging on spherical surfaces.…”

Parametric study of turbulent slot-jet impingement heat transfer from concave cylindrical surfaces

“…Frageau et al [22] computed the flow and heat transfer due to an array of circular jets impinging on concave surface for aircraft wing leading edge anti-icing application. Hu and Zhang [16] conducted numerical investigation in addition to the experimental measurement for circular water jet impingement heat transfer from a convex hemispherical surface. They, however, did not report which turbulence model was used in the computation, if any.…”

Slot jet impingement cooling of a concave surface in an annulus

“…Re ( / ) mn ave j Nu A Z B  (14) Where the constant A and the exponents m and n are to be obtained through regression analysis of the experimental data. Hence, the desired correlation for 100 ≤ Re j ≤ 1,000 and 4.2 ≤ Z/B≤ 12.5 is obtained as: …”

“…They observed three flow modes and described their behaviors. Hu and Zhang [14] experimentally and numerically studied the effects of the water-jet impingement exit velocity and the nozzle-to-surface distance on the heat transfer characteristics of a convex hemispherical surface. Their results showed that for lower Reynolds numbers, the local Nusselt number decreased from the stagnation point.…”