Turbine Blade Spacing Deviation Measurement Using Combustor Radiation
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Solution Overview
Problem
Conventional stress measurement systems in gas turbine engines face challenges in accurately detecting the time of arrival of turbine blades due to noise from background radiation generated by the combustor, which affects the detection of vibratory modes and signal strength.
Innovation Solution
A background radiation measurement system that includes a probe positioned to detect radiation emitted from the combustor, an infrared sensor to generate a signal based on the passage of the airfoil's edge into its line-of-sight, and a controller to calculate spacing deviations by comparing expected and actual time of arrival.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser source and photo-detector system is used to measure turbine blade stress, then measurement capability is provided, but background radiation from the combustor generates noise that affects detection accuracy
Solution Approach 1:
The patent converts the harmful background radiation from the combustor into a beneficial signaling mechanism. Instead of treating the combustor radiation merely as noise to be filtered, the system uses the radiation source to illuminate the turbine blades, and detects the modulation of this radiation as blades pass through the field of view. The photo-detector captures the radiation signal, and the system identifies blade passage by detecting changes in the radiation pattern, effectively transforming the harmful thermal radiation into a useful measurement signal for determining blade time of arrival and vibratory modes.
2Object-affected harmful factors
If filters are used to block background radiation from the combustor, then noise is reduced, but system complexity increases
Solution Approach 1:
The patent extracts only the necessary measurement function from the complex laser-based system. Instead of using a full laser source with transmit fibers, lenses, and complex filtering systems, the invention extracts the essential measurement capability by using a simpler photo-detector system that directly detects modulated radiation from the combustor. This extraction approach eliminates unnecessary system components while maintaining the core measurement function of detecting blade passage and vibratory modes.
3Loss of energy
If remote mounting of the probe is used, then aerodynamic losses are reduced, but signal strength decreases
Solution Approach 1:
The patent changes the detection parameters to optimize performance at remote mounting distances. The photo-detector system is configured to detect specific wavelength ranges and modulation patterns of the radiation signal, enhancing sensitivity to blade passage events. The system processes the radiation signal to extract time of arrival information and vibratory mode data, maintaining measurement accuracy despite the increased distance from the turbine blades. This parameter optimization allows the probe to be mounted remotely with minimal aerodynamic interference while preserving sufficient signal strength for accurate measurements.
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
This system enhances the detection of vibratory modes and signal strength by utilizing background radiation, reducing system complexity and aerodynamic losses, and providing accurate blade spacing deviation measurements.
Implementation Method 1
A background radiation measurement system is disclosed which includes a probe positioned a distance from the turbine blades configured to detect radiation emitted from a background radiation source
Implementation Method 2
a sensor operatively coupled to the probe and configured to generate a signal utilized to determine when the edge of the airfoil extends into a line-of-sight between the probe and the radiation source
Data Source
AI summary
A turbine section according to an exemplary aspect of the present disclosure includes, among other things, an airfoil including an edge and a probe positioned a distance from the airfoil. The probe is configured to detect radiation emitted from a radiation source. A sensor is operatively coupled to the probe and is configured to generate a signal utilized to determine when the edge of the airfoil extends into a line-of-sight between the probe and the radiation source.