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

需求：现代燃气轮机发动机对更高效率的推动导致涡轮进气温度(TETS)不断提高。高压涡轮叶片现在运行的环境中，周围的气体温度超过了制造叶片的材料的熔点。为了解决这一问题，发动机压缩机部分的空气被排出，用来冷却叶片。采用了两种冷却技术来防止高TETS对叶片的损伤：气膜冷却，在叶片表面引入一层薄薄的冷却剂，以降低换热的驱动温度；内部冷却，冷却剂通过叶片内的一系列通道，对内表面的热量进行对流。涡轮叶片冷却的实验研究主要是将气膜冷却和内部冷却分开处理。这种方法未能捕捉到共轭换热效应以及由此产生的对部件温度分布的影响。其结果是，叶片经常被保守地过冷，以牺牲发动机的效率为代价。将气膜和内部冷却相结合的实验数据将为叶片温度预测提供更大的信心，减少对冷却剂的过度使用，并降低冷却不足的叶片重新设计成本高昂的风险。目的：目的是通过使用新的、高精度的实验技术，从根本上探索气膜和内冷却燃气轮机叶片中的热传递。为实现这一目标而建立的目标是：1.设计和制造模块化测试设备，以模拟冷却燃气轮机叶片简化部分的传热。2.利用红外热像仪测量瞬时换热实验的换热系数。这将为匹配Biot技术的应用提供重要数据。实现了匹配Biot技术，从稳态换热实验中获得了无因次表面温度分布。使用CO2-PLIF和V3V技术提供冷却射流和主气路之间混合的基本流体动力学的详细信息，以及用于CFD验证的高质量三分量速度数据。测试发动机-在一系列操作条件下具有代表性但通用的薄膜内部冷却配置。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-比奥特方法，可以将结果缩放到真实世界的值。所使用的几何形状也将是通用的，以便为学者和发动机设计者提供测量数据库。资源和规划：叶轮机械研究中心(TRC)将为技术人员提供时间和激光单元内的空间。该钻井平台的建造将由庞特尼博士的EPSRC First Grant提供资金。目前的计划包括测试台的第一年设计、制造和调试，然后是两年的测试和六个月的编写。博士学位将于2022年3月完成(包括撰写)。

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.