Heat Transfer Measurements Downstream of Trenched Film Cooling Holes Using a Novel Optical Two-Layer Measurement Technique
Heat Transfer Measurements Downstream of Trenched Film Cooling Holes Using a Novel Optical Two-Layer Measurement Technique
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DOI：
10.1115/1.4031919
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发表时间：
2015-06
影响因子：
1.7
通讯作者：
P. Schreivogel;M. Pfitzner
中科院分区：
文献类型：
--
作者：
P. Schreivogel;M. Pfitzner
提出了一种新的稳态传热测量方法。在表面和壁内一定深度处测量温度分布，为三维热流密度计算提供边界条件。通过采用叠加法测量两种不同的0.75D深窄沟槽和圆柱孔下游的传热和气膜冷却效果，验证了该技术的实际应用。与圆柱形孔相比，两种沟槽的几何形状都导致了传热系数的增加，这可能是由于从沟槽中发散出来的高湍流附加冷却膜造成的。高热传递区域是可见的，那里的再循环气泡或大量的冷却剂预期。将密度比从1.33增加到1.60，传热系数略有降低，冷却效率有所提高。两种沟槽的净热通量降低（NHFR）都优于圆柱孔，特别是在动量通量比最高时。
A new approach for steady-state heat transfer measurements is proposed. Temperature distributions are measured at the surface and a defined depth inside the wall to provide boundary conditions for a three-dimensional heat flux calculation. The practical application of the technique is demonstrated by employing a superposition method to measure heat transfer and film cooling effectiveness downstream of two different 0.75D deep narrow trench geometries and cylindrical holes. Compared to the cylindrical holes, both trench geometries lead to an augmentation of the heat transfer coefficient supposedly caused by the highly turbulent attached cooling film emanating from the trenches. Areas of high heat transfer are visible, where recirculation bubbles or large amounts of coolant are expected. Increasing the density ratio from 1.33 to 1.60 led to a slight reduction of the heat transfer coefficient and an increased cooling effectiveness. Both trenches provide a net heat flux reduction (NHFR) superior to that of cylindrical holes, especially at the highest momentum flux ratios.