An experimental investigation into combined film and internal cooling of turbine blades

需求：现代燃气涡轮发动机对更高效率的追求导致了涡轮入口温度（TETs）的不断提高。高压涡轮叶片现在在周围气体温度超过制造叶片的材料熔点的环境中运行。为了解决这个问题，从发动机的压气机部分排出的空气被用来冷却叶片。采用两种冷却技术来防止高TETs对叶片的损坏：薄膜冷却，在叶片表面引入一层冷却剂薄膜，以降低传热的驱动温度；内部冷却，冷却剂通过叶片内部的一系列通道，从内部表面对流热量。涡轮叶片冷却的实验研究主要是将气膜冷却和内部冷却作为单独的主题。这种方法无法捕捉到共轭传热效应以及由此产生的对部件温度分布的影响。这样做的后果是，叶片往往以牺牲发动机效率为代价，保守地过冷。结合气膜和内部冷却的实验数据将为叶片温度预测提供更大的信心，减少多余冷却剂的使用，并降低因冷却不足而重新设计叶片的昂贵风险。目的：目的是“通过使用新颖、高度精确的实验技术，从根本上探索气膜和内冷燃气轮机叶片的传热”。为实现这一目标而确定的目标是：1。设计和制造一个模块化测试设备，模拟冷却燃气轮机叶片简化部分的传热。2. 利用红外热像仪从瞬态换热实验中获得换热系数。这将为匹配生物技术的应用提供重要的数据。实施匹配biot技术，从稳态传热实验中获得无量纲表面温度分布。使用CO2-PLIF和V3V技术，可以提供冷却射流与主气路混合的基本流体动力学细节，以及用于CFD验证的高质量三分量速度数据。在一系列操作条件下测试具有代表性但通用的发动机内膜冷却配置。范围：作为该项目的一部分，收集的数据将在环境条件下进行，以避免复杂且昂贵的钻机设计。利用已建立的匹配生物方法将允许将结果缩放到真实世界的值。使用的几何形状也将是通用的，以便为学者和发动机设计师提供测量数据库。资源和规划：涡轮机械研究中心（TRC）将为技术人员提供时间以及激光单元内的空间。该钻机的建造将由Pountney博士的EPSRC第一笔拨款资助。目前的计划包括第一年的设计、制造和测试平台的调试，随后是两年的测试和六个月的编写。博士学位将于2022年3月前完成（包括论文撰写）。

Need:The push for higher efficiencies in modern gas turbine engines has led to ever-increasing Turbine Entry Temperature (TETs). High pressure turbine blades now operate in an environment where the surrounding gas temperature exceeds the melting point of the materials from which the blades are made. To combat this, air from the compressor section of the engine is bled off and used to cool the blades. Two cooling techniques are employed to prevent damage to the blade from the high TETs: film cooling, where a thin film of coolant is introduced to the surface of the blade to reduce the driving-temperature for heat transfer; and internal cooling, where coolant is passed through a series of passages within the blade to convect heat from the internal surfaces.Experimental research into turbine blade cooling has predominately treated film cooling and internal cooling as separate topics. This approach fails to capture conjugate heat transfer effects and the resulting impact on the component temperature distribution. The consequence of this is that blades are often conservatively overcooled at the expense of engine efficiency. Experimental data that couples the film and internal cooling would provide greater confidence in blade temperature predictions, reducing the need for superfluous use of coolant and lowering the risk of costly re-design of blades with inadequate cooling. Aim:The aim is to "fundamentally explore the heat transfer in film and internally cooled gas turbine blades through the use of novel, highly accurate experimental techniques". The objectives established to meet this aim are to:1. Design and manufacture a modular test facility to model the heat transfer in a simplified portion of a cooled gas turbine blade. 2. Use IR thermography to obtain heat transfer coefficients from transient heat transfer experiments. This will provide important data for application of the matched-Biot technique.3. Implement the matched-Biot technique to obtain non-dimensional surface temperature profiles from steady-state heat transfer experiments.4. Use the CO2-PLIF and V3V technologies to provide detail on the fundamental fluid dynamics of the mixing between the cooling jets and main gas path, and high-quality three-component velocity data for CFD validation.5. Test engine-representative, but generic, film-internal cooling configurations at a range of operating conditions.Scope:The data collected as part of this project will be at ambient conditions to avoid a complex and costly rig design. Utilising the established matched-Biot method will allow scaling of the results to real world values. The geometries used will also be generic to allow a database of measurements to be made available for academics and engine designers.Resources and Planning:The Turbomachinery Research Centre (TRC) will provide technician time as well as floor space within their laser cell. The build of the rig will be financed by Dr. Pountney's EPSRC First Grant. The current plan includes a first year of design, manufacture, and commissioning of the test rig, followed by two years of testing and six months of writing up. The PhD will be complete (including write-up) by March 2022.