Surface Curvature Effect on Slot-Air-Jet Impingement Cooling Flow and Heat Transfer Process

Abstract

Experiments are performed to study surface curvature effects on the impingement cooling flow and the heat transfer processes over a concave and a convex surface. A single air jet issuing from different size slots continuously impinges normally on the concave side or the convexside of a heated semicylindrical surface. An electrical resistance wire is used to generate smoke, which allows us to visualize the impinging flow structure. The local heat transfer Nusselt number along the surfaces is measured. For impingement on a convex surface, three-dimensional counterrotating vortices on the stagnation point are initiated, which result in the enhancement of the heat transfer process. For impingement on a concave surface, the heat transfer Nusselt number increases with increasing surface curvature, which suggests the initiation of Taylor–Go¨rtler vortices along the surface. In the experiment, the Reynolds number ranges from 6000 to 350,000, the slot-to-plate spacing from 2 to 16, and the diameter-to-slot-width ratio D/b from 8 to 45.7. Correlations of both the stagnation point and the average Nusselt number over the curved surface, which account for the surface curvature effect, are presented.

Computational Methodology for Bleed Air Ice Protection System Parametric Analysis

“…Although the positive value of the ZP exponent may be correct for the present piccolo tube configuration, it can become negative for piccolo tubes placed farther away from the wall. This was experimentally observed by Gau and Chung [57] for a rectangular (or slot) cooling jet impinging on a concave surface, as shown in Table 3.5. Note that the DP parameter in the impinging jet Nusselt number correlation indicates the influence of the piccolo tube diameter D on the internal flow heat transfer.…”

Experimental study of jet impingement heat transfer on a variable-curvature concave surface in a wing leading edge

“…The thinning of the boundary layer and the generation of Taylor-Görtler vortices might be the reasons responsible for such an enhancement. Gau et al [15] and Cornaro et al [16] presented the flow visualization of jets impinging on both convex and concave surfaces.…”

Transport phenomenon in a jet type mold cooling pipe

“…To optimize heat transfer, an understanding of the temperature field as well as the velocity field is essential, in particular near the impingement surface where the flow characteristics dominate the heat transfer process. Heat transfer distributions of jet impingement and the effect of various geometric and flow parameters on heat transfer are well documented, for example by Miranda and Campos [1,2], Kayansayan and Kucuka [3], Hrycak [4], Gau and Chung [5] and Lee et al [6].…”