Transpiration Cooling Systems for Jet Engine Turbines and Hypersonic Flight

这笔赠款将改变对下一代冷却系统的理解和预测，使英国能够在喷气发动机和高超声速飞行器冷却技术方面建立全球领先地位。我们的目标是使蒸腾冷却--被公认为终极对流冷却系统--在英国制造的喷气发动机和欧洲高超声速飞行器成为现实。冷却剂有可能实现更高的循环温度(根据热力学第二定律提高效率)，但不可避免地会引入涡轮级损失(降低效率)。冷却系统的改进必须实现更高的涡轮入口温度(TET)，同时使用最少的冷却剂流量以达到所需的部件寿命。对于高速飞行，热传递主要由空气动力加热主导，再入时气体温度超过太阳表面温度。热保护系统的任何热传递的减少都将最终导致更低的质量，从而降低发射成本。此外，更低的温度可以成为目前受温度限制的更高性能技术的推动力。喷气发动机和高超声速飞行所能达到的最高温度都受到所使用的材料和冷却技术的限制。蒸腾流的冷却益处是众所周知的，但由于缺乏合适的多孔材料，以及精确模拟空气热应力场和机械应力场的挑战，这项技术在英国的航空航天领域的应用一直受到阻碍。我们的方法将实现流场、热场和应力场之间的耦合，以一种跨学科的方法同时研究，我们认为这是获得最佳蒸腾系统的关键。这项Progreamme Grant将使各自领域的世界领先者能够共同努力，解决因应用蒸腾冷却而产生的跨学科问题，从而导致这项技术的快速创新。这一应用是及时的，因为拟议的研究将使英国航空航天工业能够利用材料、制造能力、实验设备/测量技术和计算方法的最新发展来发展发汗冷却应用的科学。伯明翰大学高温研究中心将提供铸造具有孔洞的高温合金涡轮翼型的方法。拟议的拨款将允许在铸造系统方面进行创新，将铸造专业知识与EPSRC最近资助的研究计划中的空气热和应力建模结合起来。它还建立在EPSRC资助的研究中进行的超高温陶瓷和碳复合材料的材料开发基础上，使用可控的孔隙率和多层复合材料。它还将提供在真实飞行条件和材料温度下将流动与材料(多孔性和非多孔性)直接耦合的第一次机会。最近在牛津大学和帝国理工学院NWTF计划(EPSRC/ATI资助)下对英国风洞的投资将允许使用先进的激光技术直接复制飞行中看到的温度和热流。傅立叶叠加在CFD网格中模拟气膜冷却的最新发展现在可以扩展到提供一种突破性的方法来预测高孔率/发汗冷却系统的冷却流动和金属效率。欧洲航天局最近确定了高超声速飞行对单次烧蚀热保护系统替代品的迫切需求。这一领域的投资是巨大的，发汗冷却已被确定为一种很有前途的冷却技术。劳斯莱斯已经开始加速投资未来喷气发动机的新技术，包括先进的

This grant will deliver a step change in the understanding and predictability of next generation cooling systems to enablethe UK to establish a global lead in jet engine and hypersonic vehicle cooling technology.We aim to make transpiration cooling, recognised as the ultimate convective cooling system, a reality in UK produced jetengines and European hypersonic vehicles. Coolant has the potential to enable higher cycle temperatures (improving efficiency following the 2nd law of thermodynamics) but invariably introduces turbine stage losses (reducing efficiency). Cooling system improvement must enable higher Turbine Entry Temperature (TET) while using the minimum amount of coolant flow to achieve the required component life. For high speed flight, heat transfer is dominated by aerodynamic heating with gas temperatures on re-entry exceeding those at the surface of the sun. Anyreduction in heat transfer to the Thermal Protection System will ultimately lead to lower mass, allowing for decreased launch costs Furthermore, the lower temperatures could serve as an enabler for higher performance technologies which are currently temperature limited.The highest temperatures achievable for both jet engines and hypersonic flight are limited by the materials and coolingtechnology used. The cooling benefits of transpiration flows are well established, but the application of this technology to aerospace in the UK has been prevented by the lack of suitable porous materials and the challenge of accurately modelling both the aerothermal and mechanical stress fields. Our approach will enale the coupling between the flow, thermal andstress fields to be researched simultaneously in an interdisciplinary approach which we believe is essential to arrive at the best transpiration systems. This Progreamme Grant will enable world leaders in their respective fields to work together to solve the combination of cross-disciplinary problems that arise from the application of transpiration cooling, leading to rapid innovations in this technology. Theapplication is timely since the proposed research would enable the UK aerospace industry to capitalise on recentdevelopments in materials, manufacturing capability, experimental facilities/measurement techniques and computationalmethods to develop the science for the application of transpiration cooling.The High Temperature Research Centre at Birmingham University will provide the means to cast super alloy turbine aerofoils with porosity. Theproposed grant would allow innovation in the cast systems arising from combining casting expertise with aerothermal andstress modelling in recent EPSRC funded research programmes. It also builds upon material development of ultra-hightemperature ceramics and carbon composites undertaken in EPSRC funded research, by use of controlledporosity and multilayer composites. It will also provide the first opportunity to undertake direct coupling of the flow with thematerials (porous and non-porous) at true flight conditions and material temperatures.Recent investment in the UK's wind tunnels under the NWTF programme (EPSRC/ATI funded) at both Oxford University andat Imperial College will allow for direct replication of temperatures and heat fluxes seen in flight and interrogated usingadvanced laser techniques. Recent development of Fourier superposition in CFD grids for modelling film cooling can nowbe extended to provide a breakthrough method to predict cooling flow and metal effectiveness for highporosity/transpiration cooling systems.The European Space Agency has recently identified the pressing requirement for alternatives to one-shot ablative ThermalProtection Systems for hypersonic flight. Investment in this area is significant and transpiration cooling has been identifiedas a promising cooling technology. Rolls-Royce has embarked upon accelerated investment in new technologies for future jet engines including the ADVANCE