Flow and heat transfer in complex film cooling configurations for application in future gas turbine combustors

未来燃气涡轮机燃烧室的燃烧室冷却方案必须以最小量的冷却空气以最大冷却效率运行。当使用低排放稀薄燃烧技术时，燃料喷射器中需要大部分空气，而同时热气体温度继续升高，以便获得最大的燃气涡轮机处理效率。当使用泻流冷却时，冷却空气射流的提升和薄膜冷却效率的降低尤其发生在高吹风速率下，这是燃气涡轮机燃烧应用的典型情况。在新的冷却配置中，如沟槽冷却，其中来自泻流射流的冷却空气横向分布，这部电梯-本研究的目的是对发散冷却中的流动和传热现象有更深入的物理理解通过实验和数值研究相结合的沟槽薄膜冷却配置相比。重点将放在沟槽冷却结构中复杂的非定常流动、混合和传热过程的研究上，这一点还没有得到很好的理解。使用生成的结果，优化的薄膜冷却装置可以开发出一个均匀的和（大范围的操作条件）强大的冷却膜在最小的冷却空气的使用。实验研究将使用光学非侵入式测量技术（PIV - PIV，红外温度测量，温度敏感的颜色- TSP），辅以热线和热电偶测量。利用高速PIV技术，可以对复杂的非定常流场结构进行详细的研究。一种新颖的组合红外线和TSP测量技术测量壁热流允许的局部分布的传热系数的测定，伴随实验的CFD模拟进行使用商业CFD代码（FLUENT与可实现的k-reliable模型）。对于大尺度非定常流结构的详细数值研究，将使用该研究所已经建立的开源CFD代码OpenFOAM进行大涡模拟。

Combustor cooling concepts for future gas turbine combustors must operate with a minimum amount of cooling air at maximum cooling efficiency. When using the low emission lean combustion technology, most of the air is required in the fuel injector, while at the same time the hot gas temperatures continue to rise in order to obtain maximum gas turbine process efficiency. When using effusion cooling, a liftoff of the cooling air jets and a reduction of the film cooling efficiency occurs especially at high blowing rates, which are typical of gas turbine combustion applications. In new cooling configurations like the trench cooling, where the cooling air from the effusion jet is distributed laterally, this lift-off effect is reduced considerably and can result in a considerably improved film cooling efficiency by one order of magnitude for some operating conditions.The goal of the proposed research project is to develop a deeper physical understanding of the detailed flow and heat transfer phenomena that occur in effusion cooling as compared to trench film cooling configurations by a combination of experimental and numerical investigations. The emphasis will be on the investigation of the complex unsteady flow, mixing and heat transfer processes in trench cooling configurations, which are not well understood. Using the generated results, optimized film cooling devices can be developed which feature a uniform and (for a large range of operating conditions) robust cooling film at minimal use of cooling air.The experimental research will use optical non-intrusive measurement technology (PIV - PIV, infrared temperature measurements, temperature-sensitive colors - TSP), supplemented by hot-wire and thermocouple measurements. Through use of high-speed PIV, the complex unsteady flow structures can be examined in great detail. A novel combination of infrared and TSP measurement techniques for measuring wall heat flows allows the determination of the local distribution of the heat transfer coefficient.The CFD simulations accompanying the experiment are performed using a commercial CFD code (FLUENT with realizable k-epsilon model). For the detailed numerical studies of the large scale unsteady flow structures, large eddy simulations will be performed using the open source CFD code OpenFOAM, which is already well established at the institute.