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Comparative analysis on the film cooling mechanisms of elliptical and cylindrical holes with 90° compound angle
International Journal of Numerical Methods for Heat & Fluid Flow ( IF 4.0 ) Pub Date : 2020-06-19 , DOI: 10.1108/hff-10-2019-0764
Guohua Zhang , Gongnan Xie , Bengt Ake Sunden

Purpose: In this study, numerical simulations are performed to compare the adiabatic film cooling effectiveness and reveal the difference of film cooling mechanisms of two models with the same geometries and cross-section areas of film holes’ exits at three typical blowing ratios (M = 0.5, 1 and 1.5). The two models are an elliptical model and a cylindrical model with 90° compound angle, respectively. Design/methodology/approach: Three different cases are considered in this work and the baseline is the model with a cylindrical film hole. The same boundary conditions and a validated turbulence model (realizable k-e) are adopted for all cases. Findings: The results show that both the elliptical and cylindrical models with 90° compound angle can enhance the film cooling effectiveness compared with the baseline. However, the elliptical model performs well at lower blowing ratios and in the near region at each blowing ratio because of the wider width of the film hole’s exit. The cylindrical model with 90° compound angle provides better film cooling effectiveness in the further downstream area of the film hole at higher blowing ratio because of the less lift-off and better coolant coverage in the larger x/D region along the mainstream direction. Originality/value: Overall, it can be concluded that although the elliptical and cylindrical models with 90° compound angle have identical hole exits, the different inlet direction and cross-sectional geometry affect the flow structures when the coolant enters, moves through and exits the hole and finally different film cooling results appear. (Less)

中文翻译:

90°复角椭圆孔与圆柱孔气膜冷却机理对比分析

目的:在本研究中,通过数值模拟比较绝热薄膜冷却效果,揭示具有相同几何形状和薄膜孔出口横截面积的两种模型在三种典型吹气比(M = 0.5、1 和 1.5)。两种模型分别是椭圆模型和复角为 90° 的圆柱模型。设计/方法/途径:在这项工作中考虑了三种不同的情况,基线是带有圆柱形薄膜孔的模型。所有情况都采用相同的边界条件和经过验证的湍流模型(realizable ke)。结果:结果表明,与基线相比,具有 90°复合角的椭圆和圆柱模型都可以提高气膜冷却效果。然而,由于薄膜孔出口的宽度较宽,椭圆模型在较低的吹气比下和在每个吹气比下的附近区域都表现良好。具有 90° 复合角的圆柱形模型在更高的吹气比下在膜孔的更下游区域提供更好的膜冷却效果,因为在沿主流方向的较大 x/D 区域中,剥离更少且冷却剂覆盖更好。原创性/价值:总的来说,可以得出结论,虽然90°复合角的椭圆和圆柱模型具有相同的孔出口,但不同的入口方向和横截面几何形状会影响冷却剂进入、穿过和离开时的流动结构。孔,最后出现不同的薄膜冷却结果。(较少的)具有 90° 复合角的圆柱形模型在更高的吹气比下在膜孔的更下游区域提供更好的膜冷却效果,因为在沿主流方向的较大 x/D 区域中,剥离更少且冷却剂覆盖更好。原创性/价值:总的来说,可以得出结论,虽然90°复合角的椭圆和圆柱模型具有相同的孔出口,但不同的入口方向和横截面几何形状会影响冷却剂进入、穿过和离开时的流动结构。孔,最后出现不同的薄膜冷却结果。(较少的)具有 90° 复合角的圆柱形模型在更高的吹气比下在膜孔的更下游区域提供更好的膜冷却效果,因为在沿主流方向的较大 x/D 区域中,剥离更少且冷却剂覆盖更好。原创性/价值:总的来说,可以得出结论,虽然90°复合角的椭圆和圆柱模型具有相同的孔出口,但不同的入口方向和横截面几何形状会影响冷却剂进入、穿过和离开时的流动结构。孔,最后出现不同的薄膜冷却结果。(较少的)原创性/价值:总的来说,可以得出结论,虽然90°复合角的椭圆和圆柱模型具有相同的孔出口,但不同的入口方向和横截面几何形状会影响冷却剂进入、穿过和离开时的流动结构。孔,最后出现不同的薄膜冷却结果。(较少的)原创性/价值:总的来说,可以得出结论,虽然90°复合角的椭圆和圆柱模型具有相同的孔出口,但不同的入口方向和横截面几何形状会影响冷却剂进入、穿过和离开时的流动结构。孔,最后出现不同的薄膜冷却结果。(较少的)
更新日期:2020-06-19
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