Film cooling over flat, convex, and concave surfaces

Abstract

Computations were performed to investigate the three-dimensional flow and heat transfer about a flat, a convex, and a concave surface cooled by jets, injected from a plenum through one row of film-cooling holes inclined at 35' with a density ratio of 1.6 and mass flux ratio of 0.5. The focus is on understanding how the mainflow distorts the jets issuing from the film-cooling holes and how the resulting interactions affect film cooling effectiveness and temperature distribution. Results are presented for the surface effectiveness, normalized temperature, velocity vector field, and contours of the vorticity magnitude. The computed results for the surface effectiveness on a flat plate were compared with experimental data, and reasonably good agreements were obtained.This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible NavierStokes), and energy closed by a low Reynolds number k-o/SST turbulence model (i.e., wall functions were not used). Solutions were generated by a cell-centered finite-volume method that uses secondorder accurate flux-difference splitting of Roe, multigrid acceleration of a diagonalized AD1 scheme with local time stepping, and patched/overlapped structured grids. In the computations, the flow is resolved not just in the cooling-jet/mainflow interaction region, but also inside the film-cooling holes and in the plenum. NOMENCLATURE D diameter of film-cooling hole DR density ratio of coolant to mainflow (p&ph) I momentum-flux ratio of coolant to mainflow (M?

Prediction of Coolant Deflection Tendencies in Rotating Film Cooling

“…They concluded that the mainstream acceleration resulted in decreasing adiabatic effectiveness values compared to the constant mainstream velocity, especially further downstream of the point of injection. Lin and Shih [10] performed a computation to investigate the threedimensional flow and heat transfer about a flat, a convex, and a concave surface cooled by jets, injected from a plenum through one row of injection holes inclined at 35 • with a density ratio of 1.6 and mass flux ratio of 0.5. The effects of curvature on flow in film-cooling hole, the evolution of vertex sheet and anti-kidney pair, and surface effectiveness were presented in their study.…”

Investigation of film cooling effectiveness and enhancement of cooling performance

“…Though computational fluid dynamics (CFD) has provided some meaningful results for film-cooling (Lin and Shih, 1999;Shih et al, 1999;Walters and Leylek, 2000;Lin and Shih, 2001;Shih and Sultanian, 2001;Liu and Fletcher, 2005), challenges remain in turbulence modeling (Durbin and Shih, 2005) and grid resolution requirements (Shih, 2006).…”

“…The goal of film cooling is to form an insulating layer of cooler air between the stator surface and the hot gas from the combustor (Han et al, 2000;Goldstein, 2001; Sundén and Faghri, 2001). Though computational fluid dynamics (CFD) has provided some meaningful results for film-cooling (see, e.g., Lin and Shih, 1999;Shih et al, 1999; Walter and Lin and Shih, 2001;Shih and Sultanian, 2001), challenges remain in turbulence modeling (Durbin and Shih, 2005) and grid resolution requirements (Shih, 2006). This challenge is exacerbated by manufacturing issues related to thermal-barrier coatings (TBCs) and by surface roughness that develop during service.…”