Effects of Injection Angles and Aperture Ratios on Film Cooling Performance of Sister Holes
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https://doi.org/10.1007/s11630-020-1315-1
Article ID: 1003-2169(2020)00-0000-00
Effects of Injection Angles and Aperture Ratios on Film Cooling Performance of Sister Holes LI Mingchun, HE Yeguang, LI Rundong*, YANG Tianhua College of Energy and Environment, Shenyang Aerospace University, Shenyang 110136, China © Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract: In this paper, to analyze the influences of the injection angles and aperture ratios (AR) of the primary hole and the side hole on the film cooling performance of a flat plate model, pressure sensitive paint (PSP) technology was used to study the forward and backward jet of a single hole and four sister holes, and a numerical simulation was supplemented to explore the flow structure of the sister holes. The sister holes had a better film cooling performance than the cylindrical hole at all blowing ratios (BR). The backward jet of the primary hole or the side hole could increase the spanwise film coverage of the sister hole. In this study, with the primary hole featuring a backward jet and the side hole featuring a forward jet, the film cooling performance was the best, 11.9 times higher than the areal mean film cooling efficiency of the cylindrical hole when AR=1 and BR=1.5. At a low blowing ratio, the counter-rotating vortex pair (CRVP) of the side hole could suppress the strength of the CRVP of the primary hole. At a high blowing ratio, when the primary hole featured a backward jet and the side hole featured a forward jet, the CRVP of the side hole had the optimal performance for suppressing the CRVP of the primary hole.
Keywords: sister hole, injection angle, aperture ratio, film cooling effectiveness, vorticity distribution
1. Introduction Turbine inlet temperatures have been rising, far exceeding the temperature limits of turbine blades and flame tubes. Film cooling has been widely used as the most effective cooling solution in the protection of the hot end parts of a gas turbine. The interaction between a jet and the primary flow results in complex flow structures for the film cooling of cylindrical holes, the most influential of which is the counter-rotating vortex pair (CRVP) formed inside a cooling jet [1]. Perry et al. [1–4] found that the interaction between a jet and a cross flow induced various vortex structures, and the CRVP
Received: Jun 24, 2019
AE: KAN Xiaoxu
was one of the structures that exerted the largest influence on the film cooling efficiency. The CRVP gradually lifts a jet away from the wall to reduce the cooling efficiency of film. Among the many influencing factors, the geometrical shape of a hole has the greatest influence on film cooling efficiency [5, 6]. Modification of the film hole is a research topic that has been discussed in the field of film cooling. Many studies have been carried out worldwide to improve the spanwise distribution of film and to weaken the adverse effects of reverse vortex pairs. A number of proposals for shaped holes
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