Abstract This study investigates the internal cooling processes affected by the tip bleed holes in gas turbine blades. Double bleed holes are fixed at the center of the blade tip near the pressure side and suction side, respectively. Five different arrangements of the holes along the center line of the tip are studied. The purely double holes are set as the Baseline. The purpose of the present study is to provide a new perspective of the tip film cooling to understand the internal flow processes, vorticity evolution and the mechanism of the heat transfer augmentation. A topological analysis and the boundary layer analysis methods are introduced to better understand the tip heat transfer. The total extraction area and volume is kept at the same level for all the studied cases. The results show that the Dean vortices and the near-wall vortices induced by the secondary flow contribute to the high heat transfer coefficient on the tip surface. The mixing effect of the Dean vortices and the hole extraction helps to enhance heat transfer upstream of the tip. Different arrangement of the bleed holes can affect the internal flow processes and heat transfer performance. The suction effect of the center-line bleed hole can accelerate the near-hole flow and reduce the thickness of the boundary layer. The center-line hole fitted at the middle of the tip affects significantly the rear side of the hole. Thus, the holes aligned in the middle of the tip provide the highest heat transfer and thermal performance. The thermal performance is enhanced by up to 4.7% compared with the Baseline.

中文翻译：

---

具有各种叶尖放气孔布置的燃气轮机叶片中冷却通道的涡流结构和传热增强

摘要 本研究调查了燃气轮机叶片叶尖排气孔对内部冷却过程的影响。双排气孔分别固定在靠近压力侧和吸力侧的叶片尖端中心。研究了沿尖端中心线的孔的五种不同排列。纯双孔设置为基线。本研究的目的是提供叶尖薄膜冷却的新视角，以了解内部流动过程、涡度演变和传热增强机制。介绍了拓扑分析和边界层分析方法，以更好地了解尖端传热。对于所有研究案例，总提取面积和体积保持在同一水平。结果表明，二次流引起的迪安涡和近壁涡有助于尖端表面的高传热系数。Dean 涡流和孔提取的混合效应有助于增强尖端上游的热传递。排气孔的不同布置会影响内部流动过程和传热性能。中心线放气孔的吸力作用可以加速近孔流动，降低边界层厚度。安装在尖端中间的中心线孔显着影响孔的后侧。因此，在尖端中间对齐的孔提供最高的传热和热性能。与 Baseline 相比，热性能提高了 4.7%。