To improve the film cooling performance by shaped injection holes for the turbine blade leading edge region, we have investigated the flow characteristics of the turbine blade leading edge film cooling using five different cylindrical body models with various injection holes, which are a baseline cylindrical hole, two laidback (spanwise-diffused) holes, and two tear-drop shaped (spanwise- and streamwise-diffused) holes, respectively. Mainstream Reynolds number based on the cylinder diameter was 7.1 x 10~4 and the mainstream turbulence intensities were about 0.2%. The effect of injectant flow rates was studied for various blowing ratios of 0.7, 1.0, 1.3 and 1.7, respectively. The density ratio in the present study is nominally equal to one. Detailed temperature distributions of the cylindrical body surfaces are visualized by means of an infrared thermography (IRT). Results show that the conventional cylindrical holes have poor film cooling performance compared to the shaped holes. Particularly, it can be concluded that the laidback hole (Shape D) provides better film cooling performance than the other holes and the broader region of high effectiveness is formed with fairly uniform distribution.
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机译：为了通过涡轮叶片前缘区域的成形喷射孔提高薄膜冷却性能，我们研究了使用具有不同喷射孔的五个不同圆柱体模型（即基线圆柱形孔）对涡轮叶片前缘薄膜冷却的流动特性。分别有两个随钻散开的孔和沿水滴散开的两个孔。基于汽缸直径的主流雷诺数为7.1 x 10〜4，主流湍流强度约为0.2％。分别针对0.7、1.0、1.3和1.7的各种吹炼比研究了喷射流速的影响。本研究中的密度比名义上等于1。圆柱体表面的详细温度分布通过红外热像仪（IRT）可视化。结果表明，与圆柱形孔相比，常规的圆柱形孔的薄膜冷却性能较差。特别地，可以得出的结论是，与其他孔相比，后备孔（D型）提供了更好的薄膜冷却性能，并且形成了较宽的高效区域，分布相当均匀。
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