Wireless Temperature Sensor for Gas Turbine Blades
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Solution Overview
Problem
Existing temperature measurement systems are not suitable for harsh environments like gas turbine engines due to issues such as structural interference, measurement errors, and the need for external power, and they fail to provide accurate and durable temperature measurements that can withstand extreme temperatures and mechanical stress.
Innovation Solution
A wireless temperature measurement system using a thin film sensor with a dielectric layer and a diode, where the sensor has a buried portion coupled to the object and an exposed portion for RF signal transmission, allowing for temperature measurement without external power and with minimal mechanical and thermal mass, enabling robust performance up to 1200°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If embedded thermocouple wires are used in blade or vane wall, then temperature monitoring is achieved, but structural and aerodynamic problems occur including flow perturbation
Solution Approach 1:
The patent extracts the temperature sensing function from intrusive embedded wires and implements it through a non-contact optical method. A phosphor coating is applied to the blade surface, and temperature is measured by analyzing the decay rate of phosphorescence emitted when excited by a light source, eliminating the need for physical wire embedding that disrupts airflow.
Solution Approach 2:
The patent replaces the mechanical embedded thermocouple system with an optical measurement system. Instead of using physical wires that must be embedded in the blade structure, the invention uses optical excitation of phosphor materials and detection of emitted light characteristics to measure temperature non-intrusively.
2Reliability
If thermal spray thermocouples with ceramic coatings are used, then temperature measurement is achieved, but significant measurement error occurs due to thermal mass
Solution Approach 1:
The patent replaces contact-based thermal measurement with optical measurement. By using phosphor materials whose decay characteristics depend on temperature and measuring them through light emission and detection, the system eliminates thermal mass effects that plague embedded thermocouples and spray-on thermocouple systems.
Solution Approach 2:
The patent exploits changes in the temporal characteristics of phosphorescence emission (an optical property) as a function of temperature. The decay rate of the phosphorescent glow changes with temperature, providing a temperature-dependent optical signal that can be measured without thermal mass interference.
3Ease of operation
If infrared photography is used for surface temperature measurement, then non-contact measurement is achieved, but reliable measurement is difficult due to light scattering by smoke or particulates
Solution Approach 1:
The patent uses phosphorescence emission in the visible or near-visible spectrum rather than infrared detection. The phosphor coating is excited by a light source and emits characteristic decay signals that are detected optically. This approach is less susceptible to scattering by smoke and particulates compared to infrared methods, while still providing non-contact measurement.
4Ease of manufacture
If thermal paints are used for temperature indication, then visual temperature distribution is achieved, but poor adhesion requires special techniques to survive harsh environment
Solution Approach 1:
The patent uses phosphor materials that can be incorporated into durable coating formulations suitable for harsh environments. These phosphor-containing coatings can be applied as thin films that adhere to turbine blade surfaces and withstand the thermal and mechanical conditions while maintaining their temperature-sensitive optical properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides accurate, durable, and sensitive temperature measurements with a small footprint, avoiding structural interference and measurement errors, and allows for rapid temperature response and communication of data outside the gas turbine engine.
Implementation Method 1
a dielectric layer disposed on the object of interest
Implementation Method 2
a diode coupled in parallel between the object of interest and the exposed portion of the antenna
Implementation Method 3
The antenna is configured to receive interrogating signals from a transmitter, and to transmit response signals
Data Source
AI summary
A temperature measurement system capable of operating in harsh environments including a temperature sensor having an antenna, diode, and dielectric layer disposed on the object of interest is provided, wherein the antenna includes a buried portion that extends through and is electrically coupled to the object of interest, and an exposed portion disposed upon an outer surface of the dielectric layer and the diode is coupled between the object of interest and the exposed portion of the antenna. The antenna is configured to receive interrogating signals from a transmitter, and to transmit response signals corresponding to the resonant frequency of the temperature sensor and its harmonics, which are indicative of the measured temperature of the object of interest. A receiver detects the response signals and correlates the frequency to a known temperature response of the dielectric material. Methods of making and using the temperature measurement system are also provided.