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Flow and heat transfer characteristics of double-wall cooling with multi-row short film cooling hole arrangements
International Journal of Thermal Sciences ( IF 4.9 ) Pub Date : 2021-03-25 , DOI: 10.1016/j.ijthermalsci.2021.106878
Yuyang Liu , Yu Rao , Li Yang , Yamin Xu , Alexandros Terzis

The double-wall cooling systems with internal jet impingements and external film cooling are greatly applicable in modern turbine blades, providing enhanced cooling capabilities compared to the conventional passage cooling. This paper presents experimental and numerical results of flow and heat transfer characteristics of a double-wall cooling configuration, which has an inline short film cooling hole arrangement. A transient infrared thermography technique was used in this study, and managed to obtain the external-wall adiabatic film cooling effectiveness and heat transfer coefficients during a single transient test. A series of steady-state Reynolds Averaged Navier-Stokes (RANS) simulations adopting polyhedral meshes and the Shear-Stress Transport (SST) kω turbulence model were conducted to characterize internal heat transfer as well as overall cooling effectiveness. Of interest are the influences of blowing ratio on flow and heat transfer, the characteristics with the inline short film cooling hole arrangement, and the effects of wall thickness on film cooling effectiveness. On the basis of validations with experiments, the numerical computations revealed that the internal heat transfer dominants double-wall cooling performance with the inline short hole arrangement. Comparing to the staggered arrangement, the inline arrangement can achieve comparable cooling performance with a lower pressure loss for the coolant, which is due to the better complementarity between internal and external heat transfer, as well as a less deteriorated parameter of net heat flux reduction (NHFR) at the high blowing ratio. Moreover, the short hole effect in the double-wall cooling leads to the decreased adiabatic film cooling effectiveness on the external surface especially when the BR is higher than 0.3 and the L/Df is lower than 1.5, and this is caused by the in-hole anti-vortex interacting with the mainstream flow. Additionally, the correspondences between the flow structure and heat transfer characteristics in the double-wall cooling are described in this paper.



中文翻译:

多排短膜冷却孔布置的双壁冷却的流动和传热特性

具有内部射流冲击和外部薄膜冷却的双壁冷却系统非常适用于现代涡轮机叶片,与传统的通道冷却相比,可提供增强的冷却能力。本文介绍了双壁冷却结构的流动和传热特性的实验和数值结果,该结构具有串联的短膜冷却孔布置。在这项研究中使用了瞬态红外热成像技术,并在一次瞬态测试中设法获得了外壁绝热膜的冷却效率和传热系数。一系列采用多面体网格和剪切应力传输(SST)的稳态雷诺平均Navier-Stokes(RANS)模拟ķ-ω进行湍流模型以表征内部传热以及整体冷却效率。令人感兴趣的是鼓风比对流动和传热的影响,在线短膜冷却孔布置的特性以及壁厚对膜冷却效率的影响。在实验验证的基础上,数值计算表明内部传热在管线内短孔布置下具有双壁冷却性能。与交错式布置相比,由于内部和外部传热之间的互补性更好,并且净热通量降低的参数变差较小,因此串联布置可实现相当的冷却性能,同时冷却液的压力损失更低NHFR)的高吹风比。而且,双壁冷却中的短孔效应导致外表面上的绝热膜冷却效率降低,尤其是当BR高于0.3且L / D f低于1.5时,这是由内燃引起的。孔抗涡与主流流动相互作用。此外,本文还描述了双壁冷却系统中流动结构与传热特性之间的对应关系。

更新日期:2021-03-25
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