The influence of the coolant convex-ribbed passage in the trailing-edge internal region on the external film cooling characteristics is experimentally studied, using the steady pressure sensitive paint technology and transient thermochromic liquid crystal technology as the measurement methods.The effects of the straight-rib pitch and the blowing ratio on the film cooling effectiveness and convective heat transfer coefficient of the expanded trailing-edge cutback surface as well as the cutback discharge coefficient are analyzed, and the heat flux ratio introduced to evaluate the enhancement effect on the comprehensive cooling effectiveness of the compact-ribbed cases by comparing with the baseline case.The experimental results show that the cutback discharge coefficient is less affected by the blowing ratio and decreases with the increase of the rib-pitch.The convexity of the jet flow is clearly enhanced by the convex-ribbed passage, aggravating the mixing degree with the mainstream, and reducing the film cooling effectiveness in the far-downstream region of the cutback surface.The film cooling effectiveness of the ribbed case with a small rib-pitch is slightly higher than that of the case with a large rib-pitch.With the increase of the blowing ratio, the difference of the film cooling effectiveness between the cases with convex ribs and the baseline case decreases.The compact-ribbed passage can improve the heat transfer performance of the region near the slot exit, particularly for the cases with the small rib-pitch.At a high blowing ratio, the core heat transfer area near the slot exit extends along the flow direction.The convex-ribbed passage with a small rib-pitch can promote the comprehensive cooling performance of the trailing edge cutback, among which the case with rib-pitch p/h=4 improves the comprehensive cooling performance by 15%-20%, while the large rib-pitch cases significantly reduce the comprehensive cooling performance compared with the baseline case.
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