Abstract Three-dimensional conjugate computations are conducted to investigate the flow and heat transfer characteristics of a double-wall cooling system with a novel hexagonal arrangement of film cooling holes. Under the same coolant flow rate, the heat transfer and cooling performance of angled holes in the hexagonal arrangement are investigated and compared with those in the counterparts with conventional linear arrangements of external film cooling holes. The boundary condition of numerical simulations maintains the fixed jet Reynolds numbers of 10,000, 20,000 and 30,000 and the corresponding blowing ratios of 0.5, 1.0 and 1.5. Different wall thermal conductivities are respectively used in the numerical computations in order to examine the effects of Biot number of the film cooling wall on the overall cooling performance. Polyhedral meshes and Shear-Stress Transport (SST) k − ω turbulence model have been adopted in the numerical computations to obtain the detailed heat transfer and flow field. The results indicate that the hexagonal arrangement of film cooling holes shows significant advantages for the double-wall cooling scheme to decrease the external surface temperature appreciably. As the Biot number increases the overall cooling effectiveness of the double-wall system shows a downward trend, which decreases by about up to 25% in the Biot number range of 0.3–1.2. With the engine-like turbine Biot number of B i ≈ 0.56 the hexagonal arrangement improves the total heat transfer quantity inside the film cooling holes by up to 3.8 times, and enhances the overall effectiveness by up to 24.5%, as compared with the linear arrangement of straight circular film cooling holes. The combinations of the increased convective heat transfer inside the film cooling holes and the improved external film coverage induced by the hexagonal arrangement are the main contributions to the improvement of overall cooling performance.

中文翻译：

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带内射流冲击和外六边形气膜冷却孔排列的双壁冷却数值模拟

摘要 通过三维共轭计算研究了具有新型六边形薄膜冷却孔排列的双壁冷却系统的流动和传热特性。在相同的冷却剂流量下，研究了六角形排列的斜孔的传热和冷却性能，并与传统的外膜冷却孔线性排列的对应物进行了比较。数值模拟的边界条件保持固定射流雷诺数为 10,000、20,000 和 30,000，相应的吹气比为 0.5、1.0 和 1.5。数值计算中分别采用了不同的壁面热导率，以检验气膜冷却壁面比奥数对整体冷却性能的影响。在数值计算中采用了多面体网格和剪切应力传递 (SST) k - ω 湍流模型，以获得详细的传热和流场。结果表明，薄膜冷却孔的六边形排列对于双壁冷却方案显示出显着降低外表面温度的显着优势。随着比奥数的增加，双壁系统的整体冷却效率呈下降趋势，在 0.3-1.2 的比奥数范围内下降约 25%。类似发动机的涡轮Biot数B i ≈ 0.56，六边形排列使薄膜冷却孔内的总传热量提高了3.8倍，整体效率提高了24.5%，与直线圆形薄膜冷却孔的线性排列相比。薄膜冷却孔内增加的对流热传递和六边形排列引起的外部薄膜覆盖率的提高是提高整体冷却性能的主要贡献。