Gas Turbine Shaft Event Detection via Speed Ratio Analysis
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Solution Overview
Problem
Existing shaft event detection systems in gas turbine engines face reliability issues due to the risk of probe failure in hot zones, making it difficult to accurately monitor certain sections of the shaft, especially when the probe is located further away from the power turbine.
Innovation Solution
A method and system that involve obtaining speed measurements from multiple locations along opposing shafts extending from a power turbine, calculating a speed ratio, and comparing it to a detection threshold to detect shaft events such as shear or over-speed conditions, thereby enhancing detection reliability without the need for probes in high-risk areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the probe is located close to the power turbine to accurately monitor shaft sections, then the measurement precision is improved, but the reliability deteriorates due to higher risk of probe failure in hot zones
Solution Approach 1:
The invention divides the shaft monitoring function into multiple independent probe locations along the shaft. Instead of relying on a single probe close to the power turbine, multiple probes are distributed at different positions (including farther locations), and their measurements are combined to achieve accurate shaft speed detection while reducing the criticality of any single probe's reliability
Solution Approach 2:
The invention uses multiple probe measurements as intermediaries to infer shaft speed. Rather than placing a single probe in the high-risk hot zone, the system uses measurements from multiple probes (some located farther away in cooler zones) as intermediate data points to calculate the overall shaft speed, thereby reducing direct exposure to harsh conditions while maintaining measurement accuracy
2Reliability
If the probe is located further away from the power turbine to reduce failure risk, then the reliability is improved, but the measurement precision deteriorates making certain shaft sections harder to monitor
Solution Approach 1:
The shaft is segmented into multiple monitoring zones with probes placed at different locations. This segmentation allows the system to use probes located farther from the power turbine (improving reliability) while still achieving accurate monitoring of all shaft sections through the combined data from multiple segmented measurement points
Solution Approach 2:
The invention transitions from a single-point measurement approach to a multi-dimensional measurement approach by placing probes at multiple locations along the shaft's length. This dimensional expansion allows the system to use farther-located probes (improving reliability) while maintaining comprehensive monitoring coverage through the additional spatial dimension
Data Source
AI summary
There is described herein methods and systems for detecting a shaft event in a gas turbine engine comprising a power turbine having a first shaft extending in a first direction and a second shaft extending in a second direction opposite from the first direction. A first speed measurement is obtained at a first location along the first shaft and a second speed measurement is obtained at a second location along the second shaft. A speed ratio is determined between the first speed measurement and the second speed measurement, and is compared to a detection threshold. The shaft event is detected when the speed ratio is beyond the detection threshold.