How to Detect Engine Surface Temperature On Turbine Blade Tips
An accurate data model of engine surface temperature is critical to the health monitoring of gas turbine engines. While the machines are large and sophisticated, they owe their efficiency to tiny, cost-effective passive sensors that monitor engine surface temperatures and the health of turbine blade tips.
Deploy Passive Sensors For Long-Term Protection
Hot spots can have a devastating impact on turbine engine reliability, component lifetimes, maintenance costs, and performance efficiency. What’s more, engine surface temperature should be monitored not only throughout each thermal cycle, but throughout the full engine life—ideally without any need for re-instrumentation.
This makes passive sensors for engine surface temperature a powerful solution. Many test labs and fleet managers realize that preliminary tests during engine development are not enough. The deployment of long-term passive sensors can help to keep Siemens gas turbine engines, for example, carefully tuned and predict maintenance needs before they become a problem.
However, not all styles of passive sensors are easy (or useful) to deploy in this way. If your goal is a continuous, real-time life model of engine surface temperature, make sure to take the following factors into consideration as you prepare for deployment of passive sensors.
Opt For Remote, Wireless Probe Technology
Wireless, networkable, and integratable passive sensors have been a priority and “need” of government programs like the Joint Strike Fighter (JSF), Defense Advanced Research Agency (DARPA), office of Naval Research (ONR), and US Air Force (USAF) for a long time—as shown in this 2006 report.
There’s good reason to yearn for remote passive sensors, too. A wireless solution enables installation in hard-to-reach locations that once required cumbersome machining or drilling to route wires (as with traditional wired thermocouple sensors). Furthermore, wireless sensors are not constrained by the diameter of the slip ring, a frequent complication that limits the number of wired sensors that can be instrumented within a turbine’s heat process.
Fortunately, this technology finally exists in a robust, cost-effective, and reliable format. Sensatek has pioneered and patented a wireless passive RF sensor technology that can be installed directly onto turbine blades for machinery that is already in active use. Being free of wires, these sensors accelerate installation and setup, also making it feasible to instrument a large number of blades across a fleet for long-term passive temperature monitoring.
Use Ceramic-Derived Contact Sensors
Non-contact optical technologies like pyrometers and IR cameras are known to suffer from inaccuracies at higher temperatures (as in the extreme environment of Siemens gas turbine engines). Furthermore, the reflective nature of the metal components makes it more complicated to measure infrared emissivity.
Better to rely on a more accurate contact-based passive sensor that is applied directly to the turbine blade or blade tips. Ceramic-derived RF sensor patches act as both resonators and integrated antennas, measuring engine surface temperature as a function of resonant frequency and communicating wirelessly with an interrogation circuit (transceiver).
Sensatek’s durable ceramic patch sensors are rated for a material lifespan of up to 40,000 hours at baseload operating conditions and long-term continuous operation at up to 1,200°C (or even 1,750°C for short durations). Research has shown that ceramic sensors can measure the surface temperature of both static and rotating engine components while surviving extreme environments for long periods of time. Passive sensors with this level of durability can be deployed for continuous monitoring of engine surface temperature throughout the lifecycle of the engine.
Multi-Sensor, In-Situ Installation and Maintenance
The simple and small form factor (Sensatek’s are 5 to 21 millimeters in diameter and only fractions of a millimeter in thickness) makes it possible to deploy passive sensors without fully dismantling Siemens gas turbine engines, rapidly accelerating the testing process while reducing costs. No machining or drilling of holes to route wires is necessary. Simply insert a high-temperature interrogation antenna into the process and deploy the sensors “in-situ” in spots that would usually be difficult to access without a full engine teardown.
With this ease of installation, you can quickly instrument a robust multi-sensor array with many advantages over single spot temperature sensors, including these benefits:
- Numerous sensor channels as a “fail safe”
- More complete and accurate picture of engine surface temperatures
- Increased engine reliability and safety
- Minimal cost impact due to cost-effective sensor materials
- Reduced wiring complexity
- Less frequent and easily predictable engine maintenance
If you’re interested in learning more about how to deploy passive sensors to monitor the health of blade tips and engine surface temperature, contact Sensatek today. Our expert team can walk you through the wireless on-blade technology and advise you on an ideal solution for your needs.