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Fiber-optic laser Doppler turbine tip clearance probe
Lars Büttner1, Thorsten Pfister, Jürgen Czarske
1Department of Electrical Engineering and Information Technology, Dresden University of Technology, Dresden, Germany. Lars.Buettner@tu-dresden.de
Optics Letters
|April 28, 2006
Summary
A novel laser Doppler method provides high-precision, in situ blade tip clearance measurements for turbomachinery. This technique achieves sub-20 micrometer uncertainty, surpassing capacitive probes for enhanced operational insights.
Area of Science:
- Mechanical Engineering
- Optical Metrology
- Turbomachinery
Background:
- Accurate measurement of blade tip clearance is critical for turbomachine efficiency and longevity.
- Existing methods like capacitive probes have limitations in precision and applicability.
Purpose of the Study:
- To present a novel, high-precision, in situ method for measuring single blade tip clearance in turbomachines.
- To demonstrate the sensor's capability in a demanding operational environment.
Main Methods:
- Development of a compact sensor head using diffractive optics and two laser wavelengths.
- Generation of superposed fanlike interference fringe systems for measurement.
- Implementation of laser Doppler velocimetry for high-resolution displacement tracking.
Main Results:
- Successful in situ tip clearance measurements on a transonic centrifugal compressor at 50,000 rpm.
- Achieved measurement uncertainty of less than 20 micrometers.
- Demonstrated a twofold improvement in accuracy compared to capacitive probes.
Conclusions:
- The developed laser Doppler system offers unprecedented precision for in situ turbomachine blade tip clearance monitoring.
- The sensor is suitable for both metallic and nonmetallic blades, with significant potential for online diagnostics.
- This advancement can lead to improved performance, reduced wear, and predictive maintenance in turbomachinery.
