Shaft Break Detection via Discrete Time Constant Analysis
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Solution Overview
Problem
Current methods for detecting shaft breakage in gas turbine engines are not accurate or timely, leading to potential catastrophic failures due to delayed shutdowns and risk of high-energy debris release.
Innovation Solution
A method and system that define a time-dependent rotational speed equation, discretize it, and use recursive least squares to determine a discrete time constant, setting a shaft break signal based on a threshold related to engine power, which is robust to high-frequency noise and applicable to any shaft system with minimal setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional shaft break detection methods are used, then the detection system is simple to implement, but the detection accuracy and timeliness are insufficient leading to delayed shutdowns
Solution Approach 1:
The patent transforms the shaft break detection problem from direct structural monitoring to dynamic parameter analysis. By calculating the discrete time constant from rotational speed measurements and comparing it against thresholds, the system detects shaft breaks through changes in system dynamics rather than direct structural sensing, achieving high accuracy with standard sensors
Solution Approach 2:
The patent replaces complex mechanical detection systems with a computational approach using standard rotational speed sensors. Instead of using specialized mechanical break detection devices, the system uses software-based analysis of rotational speed data to detect shaft breaks, reducing hardware complexity while improving detection capability
2Reliability
If traditional detection methods are used, then the system is easy to operate, but high-frequency noise interferes with detection reliability
Solution Approach 1:
The patent introduces a mathematical model (rotational speed equation with discrete time constant) as an intermediary between the raw sensor data and the shaft break detection. This model acts as a filter that extracts meaningful diagnostic information while suppressing high-frequency noise, improving detection reliability without requiring complex physical filtering
Solution Approach 2:
The system continuously monitors rotational speed and recursively calculates the discrete time constant, comparing it against thresholds to determine shaft break status. This closed-loop feedback mechanism allows the system to adapt to changing operating conditions and maintain reliable detection despite noise interference
3Measurement precision
If comprehensive shaft break detection is implemented, then detection accuracy improves, but setup burden increases requiring extensive system configuration
Solution Approach 1:
The patent creates a universal detection method that can be applied to any shaft system regardless of specific configuration. The system only requires obtaining the system inertia parameter and setting appropriate thresholds, making it broadly applicable across different engine types without requiring custom configuration for each application
Solution Approach 2:
The system automatically calculates the discrete time constant from operational data and performs self-diagnosis for shaft break detection. The method uses recursively calculated values from standard sensors without requiring external calibration or complex setup procedures, reducing implementation burden
Data Source
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AI summary
The present invention provides a method of detecting shaft break in a shaft system comprising a shaft coupled between two masses. The method comprises a number of steps. Firstly, to define a time-dependent rotational speed equation for the shaft in terms of system inertia for an engine transient event. Then to discretize the rotational speed equation in terms of a discrete time constant in the discrete domain. Then to recursively define the discretized equation to give a recursive equation and to solve the recursive equation to determine the discrete time constant. Then to define a threshold as a function of engine power and then to set a shaft break signal to TRUE if the discrete time constant is greater than the threshold. A shaft break detection system is also provided by the present invention.