Blade Tip Timing Dynamic Strain Reconstruction for Rotor Blades
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Solution Overview
Problem
Current dynamic strain reconstruction methods for rotor blades are limited to single-modal vibration and cannot accurately measure dynamic strain fields under multimodal vibration conditions, which is a challenge in ensuring the safety and integrity of high-speed rotating machinery like aircraft engines.
Innovation Solution
A dynamic strain field measuring method and system based on blade tip timing that involves establishing a three-dimensional finite element model, determining sensor positions, mapping single-point displacement to full-field dynamic strains, and using blade tip timing sensors to measure and reconstruct dynamic strains across the rotor blade surface and interior, enabling measurement under multimodal vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional strain gauges are pasted on the rotor blade surface, then dynamic strains at specific positions can be measured, but the measurement coverage is limited to finite positions and the reliability is poor
Solution Approach 1:
The patent replaces traditional contact-based strain gauges with a non-contact blade tip timing measurement system. Optical sensors mounted on the engine casing measure blade tip vibration displacements, which are then used to reconstruct dynamic strain fields throughout the blade volume, eliminating the need for physical strain gauge attachment while expanding measurement capability from discrete points to continuous field coverage.
Solution Approach 2:
The patent creates a virtual model of the rotor blade using finite element analysis and reconstructs the dynamic strain field by mapping measured blade tip vibrations to the complete blade structure. This virtual copying approach allows strain measurement at any position within the blade without physical sensors at those locations, achieving full-field measurement coverage.
2Loss of information
If multiple strain gauges are arranged on the turbine blade, then more information can be acquired, but the survival rate of strain gauges is very low in high-temperature environment
Solution Approach 1:
The patent replaces fragile contact strain gauges that fail in high-temperature environments with robust non-contact optical sensors mounted on the engine casing. The optical measurement system is not exposed to the harsh thermal environment, eliminating the survival rate problem while maintaining complete information acquisition through full-field strain reconstruction.
Solution Approach 2:
The patent uses blade tip vibration measurements as an intermediary to indirectly obtain strain information throughout the blade. Instead of placing sensors directly on the blade surface where they fail, the system measures blade tip dynamics and uses computational methods to derive strain fields, acting as an intermediary that avoids the harsh environment while capturing complete strain information.
3Adaptability or versatility
If current dynamic strain reconstruction method is used under single-modal vibration, then dynamic strain estimation can be realized, but it cannot handle multimodal vibration conditions
Solution Approach 1:
The patent implements a dynamic measurement system that adapts to varying vibration conditions. The blade tip timing system captures time-varying blade tip displacements, and the reconstruction algorithm dynamically processes signals to handle both single-modal and multimodal vibration conditions, maintaining measurement precision across different operating states through real-time data acquisition and processing.
Solution Approach 2:
The patent creates a universal measurement system that functions across multiple vibration modes. The blade tip timing measurement approach and strain reconstruction algorithm are designed to handle both single-modal and multimodal vibrations, as well as various blade operating conditions, making the system universally applicable without requiring mode-specific calibration or separate measurement systems.
Data Source
AI summary
The present invention discloses a dynamic strain field measuring method and system for a rotor blade based on blade tip timing. The method includes the following steps: establishing a three-dimensional finite element model of a to-be-measured rotor blade, and extracting modal parameters of the three-dimensional finite element model; determining the number and circumferential mounting positions of blade tip timing sensors; establishing a mapping relationship between single-point displacement and full-field dynamic strains of the blade; acquiring blade tip single-point displacement of the rotor blade based on the blade tip timing sensors; and realizing, by the single-point displacement, dynamic strain measurement in any position and direction of the rotor blade based on the mapping relationship.