Surface temperature condition monitoring methods for aerospace turbomachinery: exploring the use of ultrasonic guided waves
Surface temperature condition monitoring methods for aerospace turbomachinery: exploring the use of ultrasonic guided waves
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DOI：
10.1088/1361-6501/abda96
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发表时间：
2021-01
影响因子：
2.4
通讯作者：
Lawrence Yule;B. Zaghari;N. Harris;M. Hill
中科院分区：
文献类型：
--
作者：
Lawrence Yule;B. Zaghari;N. Harris;M. Hill
涡轮机叶片和喷嘴导向叶片（NGV）在极端温度下操作，以使发动机的热效率和功率输出最大化。本文评述了现有的涡轮机叶片和喷嘴导叶温度监测系统的适用性。离线和在线的方法，并检查其优点和缺点。离线系统的使用已经得到了很好的建立，但由于对组件的访问有限，在线系统很难实现。需要一种改进的传感器，该传感器能够在对发动机的操作条件的干扰最小的情况下真实的实时测量温度，允许操作温度增加到部件的极限并使效率最大化。声学监测技术已经用于大量的结构健康监测应用，并且具有适用于涡轮机叶片和NGV的温度监测的潜力。高温会严重影响超声换能器的响应。然而，波导和缓冲棒可用于使换能器远离极端条件，而诸如氧硼酸钇钙单晶和氮化铝等压电材料已被开发用于高温。介绍了一种基于超声导波的监测方法。涡轮机叶片和NGV的几何形状允许兰姆波通过其结构传播，并且许多冷却孔的存在将产生声学反射，该声学反射可用于监测多个位置处的温度。兰姆波的色散性质使其分析困难;然而，色散区域的波速对温度变化特别敏感，可用于监测目的。所提出的方法有可能提供高分辨率和准确性，快速响应时间，以及将传感器放置在气路之外的能力，需要进一步的研究来开发基于在极端环境中使用导波的监测系统。
Turbine blades and nozzle guide vanes (NGVs) are operated at extreme temperatures in order to maximise thermal efficiency and power output of an engine. In this paper the suitability of existing temperature monitoring systems for turbine blades and nozzle guide vanes are reviewed. Both offline and online methods are presented and their advantages and disadvantages are examined. The use of offline systems is well established but their online equivalents are difficult to implement because of the limited access to components. There is the need for an improved sensor that is capable of measuring temperature in real time with minimum interference to the operating conditions of the engine, allowing operating temperatures to be increased to the limits of the components and maximising efficiency. Acoustic monitoring techniques are already used for a large number of structural health monitoring applications and have the potential to be adapted for use in temperature monitoring for turbine blades and NGVs. High temperatures severely affect the response of ultrasonic transducers. However, waveguides and buffer rods can be used to distance transducers from extreme conditions, while piezoelectric materials such as Yttrium Calcium Oxyborate single crystals and Aluminum Nitride have been developed for use at high temperatures. A new monitoring approach based on ultrasonic guided waves is introduced in this paper. The geometry of turbine blades and NGVs allows Lamb waves to propagate through their structure, and the presence of numerous cooling holes will produce acoustic reflections that can be utilised for monitoring temperature at a number of locations. The dispersive nature of Lamb waves makes their analysis difficult; however, wave velocity in dispersive regions is particularly sensitive to changes in temperature and could be utilised for monitoring purposes. The proposed method has the potential to provide high resolution and accuracy, fast response times, and the ability to place sensors outside of the gas path. Further research is required to develop a monitoring system based on the use of guided waves in extreme environments.