Effects of Trench Structural Features on the Film Cooling Effectiveness and Particle Deposition Performances of a Fan-Shaped Hole

Abstract In the pursuit of designing a film cooling system that mitigates particle deposition and achieves high film cooling effectiveness, this paper investigates the combination of trenches with high-efficiency fan-shaped holes. Through numerical simulation methods, the current work focuses on the effect of trench depth and width on the film-cooling effectiveness and particle deposition distribution characteristics of fan-shaped holes with a trench. The RANS method with the Realizable k-ε turbulence model was used to obtain the details of the flow field. The critical velocity deposition model was used to calculate the adhesion/rebound and detachment process between the particles and the deposited wall surface. The study was performed at three different blowing ratios of 0.5, 1.0, and 2.0. Three trench heights (0.2D, 0.4D, and 0.8D) and three trench widths (0D, 0.75D, and 1.5D) were investigated. The numerical simulation results indicate that for trench depths exceeding 0.2D, there is a subsequent enhancement in film cooling effectiveness. The most significant improvement achieves an enhancement of 57% (H/D = 0.8, R/D = 0.75, M = 2.0) compared to the plate. The variation in deposition efficiency is influenced by the characteristics of the deposition target and the outflow of film-cooling air. While R/D = 0.75, The deposition efficiency for H/D = 0.8 decreases by 12% and 4.6% compared to H/D = 0.2 and H/D = 0.4 under M = 1.0. Additionally, widening trenches decreases deposition efficiency, the effects are especially pronounced with the variation in high blowing ratios.