Abstract A short pin-fin array has been used to improve the internal cooling characteristics at the trailing edge of some gas turbine blade designs. In such a cooling scheme, the pin-fin array that is sandwiched by the turbine blade’s inner surfaces, experiences a uniform-like coolant stream. The local elevation of internal heat transfer especially on the end-walls (i.e., inner blade surfaces) at the trailing edge is achieved predominantly by horseshoe vortex-type secondary flows whose fluidic behavior has been well established. A modification to this cooling scheme has been made by introducing a blockage upstream, causing multiple jets to impinge on the pin-fins – the blockage jets. Previous studies on the internal cooling scheme employing the blockage jets have assumed that the end-wall flow topology is similar to that formed by the horseshoe vortex-type secondary flows due to similar local heat transfer distributions. However, there is no detailed and sufficient acknowledgement made of the lack of an approaching boundary layer. Therefore, the present study experimentally investigates local heat transfer around a single short pin-fin subjected to a fully turbulent jet impingement simulating the blockage jet impingement and demonstrates that the end-wall flow topology loosely resembles that formed by a horseshoe vortex system and is strictly different, depending on the distance between the jet exit and the pin-fin, relative to the length of the jet’s potential core.

中文翻译：

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通过短针翅上的射流冲击增强局部端壁传热

摘要 短针翅阵列已被用于改善某些燃气轮机叶片设计后缘的内部冷却特性。在这种冷却方案中，被涡轮叶片内表面夹在中间的针翅阵列会经历类似均匀的冷却剂流。内部传热的局部升高，特别是在后缘的端壁（即内叶片表面）上，主要是通过马蹄形涡流型二次流实现的，其流体行为已得到很好的确立。通过在上游引入阻塞，对这种冷却方案进行了修改，导致多个射流撞击针翅 - 阻塞射流。先前对采用阻塞射流的内部冷却方案的研究假设端壁流拓扑类似于马蹄涡型二次流由于相似的局部传热分布而形成的流拓扑。然而，没有详细和充分地承认缺乏接近的边界层。因此，本研究通过实验研究了受完全湍流射流冲击的单个短销翅片周围的局部传热模拟堵塞射流冲击，并证明端壁流拓扑与马蹄涡系统形成的流拓扑结构松散地相似，并且是严格的不同，取决于喷流出口和针鳍之间的距离，相对于喷流潜在核心的长度。