Wireless instrumentation for aerospace applications—thermal monitoring for a gas turbine engine

Rolls-Royce are pioneers in the concept of “power-by-the-hour”, whereby they no longer sell gas turbine engines and leave maintenance and spare parts costs to the customer but rather sell a service agreement to provide thrust on an hours of use basis. This approach has reoriented engine manufacturers from selling spare parts to trying to maximise each engine’s longevity. This reorientation has introduced a new emphasis on sensing and monitoring. An example is the temperature sensors harness developed by Vibro Meter UK, a wholly owned subsidiary of Meggit Plc. Their thermocouple probes are able to withstand the high temperatures found within the gas stream. In principle, the large number of thermocouple sensors mounted within the engine could provide detailed thermal maps and thus provide for accurate diagnosis of potential problems before they occur. A difficulty, however, is that sending all the individual sensor data back to the control unit would require a large amount of heavy duty cabling, thus significantly increasing the weight of the engine. To avoid this, sensor values are averaged, and only a single cable is used. Even a single cable may be more than is necessary, however. By making use of wireless technology, low-power electronics, and advanced visualisation techniques researchers at Coventry University’s Cogent Computing Applied Research Centre (CCARC), are developing a system to wirelessly connect the high temperature thermocouples and perhaps other sensors on the gas turbine engine. Furthermore, they are looking at developing visualisation tools to ensure that the much more detailed gathered data can be easily interpreted. It is hoped that the development of such a wireless sensing system will lead to several important benefits: it will reduce the weight of the engine; it will allow a detailed map of temperatures within the gas flow of the engine to be obtained; it will allow sensor faults to be detected more readily.