Optical Blade Twist Detection for Compressor Stall Prevention
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Solution Overview
Problem
Current methods for detecting compressor stall in turbomachinery are inadequate for providing early and accurate warnings, often resulting in false indicators and inability to prevent surge, as they rely on fixed reference values and do not account for changing operating conditions.
Innovation Solution
A fiber-optic based rotating stall detection system that measures the twist profile of blades using a line probe with optical fibers, comparing the twist angle of one blade to previous profiles to detect the onset of compressor stall, allowing for real-time monitoring and prevention of stall conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed reference values are used for detecting compressor stall, then the detection system is simple to operate, but the measurement precision deteriorates due to false indicators and inability to account for changing operating conditions
Solution Approach 1:
The system transitions from fixed reference values to dynamic reference values that automatically adapt to changing operating conditions. The detector compares blade twist measurements against dynamically updated references, allowing the system to maintain measurement precision across varying compressor speeds and loads while remaining easy to operate.
Solution Approach 2:
The system implements feedback by continuously monitoring blade twist measurements and using them to update reference values. This closed-loop approach allows the detector to learn and adapt to normal operating patterns, improving measurement precision by distinguishing between normal variations and actual stall conditions.
2Measurement precision
If optical measurement of blade untwist is used, then the measurement precision improves for detecting stall onset, but the device complexity increases due to fiber-optic based line probe system
Solution Approach 1:
The system replaces complex mechanical measurement devices with an optical fiber-based line probe. By using optical fibers to measure blade twist through light reflection and intensity changes, the system achieves high measurement precision while avoiding the complexity of mechanical sensors, moving parts, and associated calibration systems.
Solution Approach 2:
The patent introduces an optical intermediary (light) as the mediator between the blade and the detector. The line probe uses light reflection from the blade surface to indirectly measure twist, providing a non-contact, non-intrusive measurement method that maintains precision without adding mechanical complexity to the blade or compressor system.
3Reliability
If early detection of rotating stall is implemented, then the reliability improves by preventing surge, but the loss of time increases due to the need for real-time monitoring and processing
Solution Approach 1:
The system performs preliminary detection by continuously monitoring blade twist and identifying early signs of rotating stall before they develop into full surge. By detecting the untwist phenomenon in its initial stages, the system provides advance warning that allows operators to take corrective action, improving reliability while minimizing the time lost to actual surge events.
Solution Approach 2:
The system maintains continuous monitoring of blade twist through the optical line probe, ensuring uninterrupted detection capability. This continuous measurement approach allows the system to track blade behavior in real-time without gaps, enabling early stall detection while optimizing the balance between monitoring duration and response time.
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
Enables accurate and timely detection of compressor stall, preventing engine mishaps and improving engine performance by identifying blade untwist patterns indicative of stall conditions, thus allowing for proactive control measures.
Implementation Method 1
a line probe for transmitting light toward and receiving reflected light from the surface of a blade moving through the optical path of the line probe
Implementation Method 2
a detector for measuring the intensity of the reflected light to determine a change in blade angle indicative of blade stall
Data Source
AI summary
Systems and methods are provided for real-time detection of the onset of stall in turbomachinery, such as compressor stall. The methods are capable of detecting and analyzing time of arrival of the chord of the blade at a sensor array to provide an indication of the onset of compressor stall. Systems for detecting the onset of compressor stall include: light sources; a plurality of linearly arranged optical fibers for transmitting light from the light sources and for receiving transmitted light reflected from a blade; a detector for measuring intensity of the reflected light; and a processor for analyzing the intensity of the reflected light to determine blade twist angle and from the blade twist angle identify onset of compressor stall. The invention can prevent the needless loss of life and assets caused by compressor stall that may lead to unexpected catastrophic failure of an engine.