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首页> 外文期刊>International Journal of Heat and Mass Transfer >Effect of transverse trench on film cooling performances of typical fan-shaped film-holes at concave and convex walls
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Effect of transverse trench on film cooling performances of typical fan-shaped film-holes at concave and convex walls

机译：横向沟槽对凹凸围墙典型扇形薄膜孔膜冷却性能的影响

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摘要

By means of a time-resolved infrared thermal imaging system, the effect of transverse trench on the film cooling performances of a fan-shaped film-hole at typical concave and convex walls was discussed deeply, from a combined view of the time-averaged parameter evaluation and cooling unsteadiness level analysis. Harmful cooling unsteadiness with high level can be estimated by large standard deviation (SD) of transient film effectiveness, which is generated by the intensified temporal evolutions of vortex-footprints at wall. Comparisons of the time-averaged experimental results revealed the design of trench at curved walls can effectively improve the film effectiveness, completely different from the phenomenon of previous flat-plate studies. The increments in area-averaged effectiveness are nearly non-sensitive to cooling air flowrate, which can reach 27% and 16% at the concave and convex walls, respectively. Meanwhile, the trench can cause the relatively small aerodynamic loss at curved walls. Analysis of cooling unsteadiness can provide the new horizon to estimate the benefits of film cooling design. Thus, the transverse trench structure is strongly suggested at convex wall, due to the reduced level of cooling unsteadiness; however, the improved level of cooling unsteadiness can impede the direct application of transverse trench at concave wall. Steady numerical simulations were also conducted to provide the detailed knowledge of flow mechanisms. The variations of intensities of vortex-system result in the different jet reattachments downstream of trench caused by wall curvature. The difference of cooling unsteadiness levels is mainly determined by the turbulence quality of impingement to trench-edge. An additional information from the present study was introduction of trench can obviously change the trends in film effectiveness and SD-contour with wall curvature. The variations of turbulence dissipation cause a break of the wall curvature effect on film effectiveness at blowing ratio (BR) of 1.5, indicting the highest effectiveness is acquired by the convex model under small BRs whereas by the concave model under large BRs.
机译：借助于时间分辨的红外热成像系统，深深地讨论了横向沟槽对典型凹凸孔的扇形膜孔的薄膜冷却性能的影响，从时间平均参数的组合视图中讨论评价和冷却不稳定水平分析。通过瞬态膜效果的大标准偏差（SD）估计具有高水平的有害冷却不稳定性，这是由墙壁的涡流脚印的强化时间演变产生的。时间平均实验结果的比较揭示了弯曲墙壁的沟槽的设计可以有效地提高膜效果，完全不同于先前平板研究的现象。区域平均效率的增量几乎对冷却空气流量几乎是不敏感的，其可以分别在凹形和凸壁处达到27％和16％。同时，沟槽可以在弯曲墙壁上引起相对较小的空气动力学损失。冷却不稳定的分析可以提供新的地平线来估算胶片冷却设计的益处。因此，由于冷却水平降低，在凸壁下强烈建议横沟结构;然而，改善的冷却水平不稳定可以妨碍横沟在凹面壁处的直接施加。还进行了稳定的数值模拟，以提供流动机制的详细知识。涡旋系统强度的变化导致壁曲率沟槽下游的不同喷射重新分离。冷却不稳定水平的差异主要由沟槽边缘的冲击的湍流质量决定。来自本研究的另一个信息是引入沟渠可以明显改变墙壁曲率的膜效果和SD轮廓的趋势。湍流耗散的变化导致壁曲率对薄膜有效性的破裂比吹延比（BR）为1.5的吹膜效果，指示凸模型在小BRS下的凸模型获取的最高效果，而在大BRS下的凹模型。

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  • 来源
    《International Journal of Heat and Mass Transfer》 |2021年第8期|121384.1-121384.16|共16页
  • 作者

    Tiao Zhang; Jian Pu; Wen-Li Zhou; Jian-Hua Wang; Wei-Long Wu; Yun Chen;

  • 作者单位

    CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Thermal Science and Energy Engineering University of Science and Technology of China No. 96 Jinzhai Road Hefei 230027 Anhui PR China;

    CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Thermal Science and Energy Engineering University of Science and Technology of China No. 96 Jinzhai Road Hefei 230027 Anhui PR China;

    CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Thermal Science and Energy Engineering University of Science and Technology of China No. 96 Jinzhai Road Hefei 230027 Anhui PR China;

    CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Thermal Science and Energy Engineering University of Science and Technology of China No. 96 Jinzhai Road Hefei 230027 Anhui PR China;

    Shenyang Aero-engine Institute of Aero Engine Corporation of China No. 1 Wanlian Road Shenyang 110015 Liaoning PR China;

    Shenyang Aero-engine Institute of Aero Engine Corporation of China No. 1 Wanlian Road Shenyang 110015 Liaoning PR China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Cooling unsteadiness level; Film effectiveness; Transverse trench; Fan-shaped film-hole; Curved wall;

    机译：冷却不稳定水平;电影效果;横沟;扇形薄膜孔;弯曲的墙壁;

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