GOALI: Turbine Film Cooling Fundamental Physics and Improved Designs for Transonic Flows

燃气轮机(喷气发动机)用于为大多数大型商用飞机提供动力。根据基本热力学原理，燃气轮机效率随着流经发动机核心的气体的最高温度的增加而增加。为了使发动机能够在更高的气体温度下运行，可以使用主动冷却来保护发动机内的金属部件。这种冷却是使用内部冷却剂通道完成的。空气冷却剂通过表面的小孔排出，空气在那里形成一层薄薄的低温流体，保护金属表面免受高温主流气体的伤害。最近的研究表明，大多数目前的气膜冷却设计都存在固有的缺陷。这是因为它们是基于一个假设，即实验室低速测试将提供适用于实际发动机运行中的高速度的性能数据。事实上，最近的研究表明，在实际燃气轮机发动机中出现的高气流速度下，性能与低速测试发现的显著不同。因此，这项研究将集中于深入了解高速对涡轮气膜冷却性能的影响，并开发专门设计用于在实际发动机速度下运行的新的气膜冷却配置。在这项研究计划中，将建造一个新的高速测试设备，用于测试实际马赫数下的涡轮冷却配置。这一测试设施将允许直接测量气膜冷却的基本流动和换热机制，使用以跨音速运行的先进的成形孔配置。计算技术将被用来确定最佳的气膜冷却配置，以减轻冷却孔内超音速流动的影响。此外，新的涡轮冷却配置将基于广泛的几何配置设计，这些几何配置由新的金属粉末添加剂制造技术实现。这些新设计预计将大幅提高涡轮冷却性能，使下一代燃气轮机发动机能够在更高的核心气体温度下运行，从而获得更高的效率。该计划的教育目标包括高级实验方法的课程开发，以及促进学生与我们的工业合作伙伴之间的密切互动，为学生提供对现实世界工程过程和技术的洞察。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Gas turbine (jet) engines are used to power most large commercial aircraft. From basic thermodynamic principles, gas turbine efficiency increases with increases in the maximum temperature of the gas flowing through the core of the engine. To enable engines to operate at higher gas temperatures, active cooling can be used to protect the metal components within the engine. This cooling is accomplished using internal coolant channels. The air coolant is exhausted through small holes in the surface where the air then forms a thin layer (film) of lower temperature fluid that protects the metal surface from the hot mainstream gases. Recent studies have shown that most all current film cooling designs are inherently flawed. This is because they are based on a presumption that laboratory testing at low speeds will provide performance data that is applicable to the high speeds that occur in actual engine operations. In fact, recent studies have shown that that at the high gas flow speeds that occur in the actual gas turbine engines, the performance is significantly different than found with low speed testing. Consequently, this study will focus on developing fundamental understanding of high speed effects on turbine film cooling performance, and developing new film cooling configurations specifically designed to operate at realistic engine speeds. For this research program, a new high speed test facility will be constructed and used to test turbine cooling configurations at realistic Mach numbers. This test facility will allow direct measurements of fundamental flow and heat transfer mechanisms for film cooling using advanced shaped hole configurations operated at transonic speeds. Computational techniques will be used to determine optimum film cooling configurations that will mitigate the effects of supersonic flows within cooling holes. Furthermore, new turbine cooling configurations will be designed based on the wide range of geometrical configurations that are enabled by new additive manufacturing techniques with metal powder. These new designs are expected to substantially increase turbine cooling performance, allowing for the development of the next generation gas turbine engines operating at much higher core gas temperatures, with resulting higher efficiencies. The educational goals of the program include course development in advanced experimental methods, and fostering close interactions between students and our industrial partner to provide students with insight into real world engineering processes and techniques.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.