Aircraft Engine Blade Damage Detection via Tip Timing
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Solution Overview
Problem
Current methods for detecting damage in aircraft engine blades, especially composite blades, are complex and require significant resources, making it difficult to implement effective on-board monitoring systems that can track blade health during flight without immobilizing the engine.
Innovation Solution
A method using multiple spatially separated sensors to measure blade-tip passage times, calculate deflections, extract dynamic components, and detect variations in dynamic behavior to identify potential damage without calculating natural frequencies, allowing for durable and resource-efficient on-board detection systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tip-timing sensors and natural frequency calculation are used to detect blade damage, then measurement precision is improved, but device complexity and computing resources required increase significantly
Solution Approach 1:
The patent extracts only the essential measurement data (blade passage time) needed for damage detection, eliminating the complex natural frequency calculation process. By focusing solely on timing measurements from multiple sensors, the system achieves adequate detection precision without requiring sophisticated computational analysis of vibrational modes.
Solution Approach 2:
The patent employs simple, inexpensive sensors that measure only passage time rather than requiring complex accelerometers or strain gauges. These basic sensors provide sufficient data for damage detection when used in combination, trading individual sensor capability for system-level detection through multiple simple measurements.
2Reliability
If multiple sensors and natural frequency calculations are implemented, then detection reliability is improved, but computing resources and processing time increase
Solution Approach 1:
The patent segments the monitoring task into simple, independent time measurements from multiple sensors rather than performing a single complex frequency analysis. Each sensor independently records passage times, and the system processes these segmented measurements to achieve reliable damage detection through comparison and pattern recognition.
Solution Approach 2:
The patent replaces the mechanical/computational system of natural frequency analysis with a temporal measurement system. Instead of calculating frequencies from vibration signals, the system directly measures passage times and uses temporal patterns to infer blade health, substituting complex computational mechanics with simpler timing measurements.
3Measurement precision
If comprehensive blade monitoring is performed, then detection precision is improved, but the system cannot be implemented on-board during flight
Solution Approach 1:
The patent makes the monitoring system self-sufficient by using existing engine operation data (blade passage timing) rather than requiring separate excitation sources or additional heavy instrumentation. The system leverages the natural rotation and passage of blades through the sensor field, eliminating the need for external testing equipment or engine shutdown procedures.
Solution Approach 2:
The patent utilizes the periodic nature of blade passage through the sensor field during normal engine operation. By measuring the regular timing intervals of blade passages and detecting deviations from the expected periodic pattern, the system achieves continuous monitoring during flight without requiring separate testing cycles or engine immobilization.
Data Source
AI summary
A method for detecting damage to one or more mobile blades of an impeller of an aircraft engine, includes measuring the speed of the engine, and for each blade acquiring, by a plurality of sensors, measurements of blade-tip passage times; calculating for each sensor, a deflection of the blade tip; extracting a dynamic component of deflection for each of the calculated deflections; detecting the number of functioning sensors; selecting the dynamic components to be processed based on the detecting step; determining, for at least one blade, a variation of the dynamic behavior of the blade for each functioning sensor; and, for each blade for which a variation of the dynamic behavior has been determined, identification of potential damage to the blade.