As-Manufactured Blade Tip Timing Correlation via Optical Topography
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Solution Overview
Problem
Existing methods for correlating strain gauge data and blade tip timing data in gas turbine engines fail to accurately account for manufacturing deviations in rotor blades, leading to variations in dynamic response and stress/deflection predictions.
Innovation Solution
The development of advanced finite element models using optical topography measurements and mesh morphing to create as-manufactured models, which allow for more accurate strain gauge to blade tip timing correlation by optimizing probe measurement locations based on actual blade chord thickness dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional as-designed finite element models are used for correlation, then the modeling process is simple, but the stress/deflection predictions are inaccurate due to manufacturing deviations
Solution Approach 1:
The patent applies preliminary action by measuring and recording the actual geometric parameters of each blade before it undergoes operational testing. These measurements are then used to create customized finite element models that accurately represent the as-manufactured geometry, preventing the accumulation of geometric deviation errors that would otherwise occur during operation.
Solution Approach 2:
The patent changes the geometric parameters of the finite element models from idealized as-designed values to actual as-manufactured values obtained through optical scanning. This parameter transformation allows the models to reflect real manufacturing variations, significantly improving the accuracy of stress and deflection predictions when correlating strain gauge and blade tip timing data.
2Reliability
If strain gauges are used to measure blade stress, then direct stress measurement is obtained, but the measurement duration is limited by short mortality rate
Solution Approach 1:
The patent uses an intermediary approach by introducing optical spot probes that measure blade tip deflection as a mediator between the physical blade state and the data needed for stress calculation. These probes have no mortality rate and can continuously measure blade deflection throughout the entire testing duration, replacing the need for long-term strain gauge installation.
Solution Approach 2:
The patent creates a virtual copy of the blade's mechanical behavior through finite element models that are continuously updated with experimental deflection data from optical probes. This digital twin approach allows stress calculations to be performed indefinitely without the physical constraints of strain gauge mortality, extending the measurement duration indefinitely.
3Measurement precision
If manufacturing deviations are accounted for using optical topography and mesh morphing, then correlation accuracy is improved, but the processing complexity increases
Solution Approach 1:
The patent applies preliminary action by performing optical topography measurements and creating as-manufactured finite element models before experimental testing begins. The geometric deviations are captured and incorporated into the computational models in advance, allowing the processing complexity to be managed systematically before data collection rather than during real-time analysis.
Solution Approach 2:
The patent implements a self-service approach where the optical topography measurements automatically generate updated geometric parameters that are directly fed into the finite element modeling process. The system self-updates the computational models with actual manufacturing variations without requiring manual intervention, reducing the effective processing complexity despite the advanced techniques used.
Data Source
AI summary
The present disclosure is directed to a method and system to develop finite element (FE) models of as-manufactured turbomachinery blades using a combination of optical topography measurements, mesh morphing and strain gauge measurements. The method and system improves strain gauge to blade tip timing correlation using as-manufactured blade dimensions with finite element modeling.