Application of Microwave Sensing to Blade Health Monitoring

David Kwapisz, Michaël Hafner, and Ravi Rajamani
Submission Type: 
Full Paper
phmce_12_023.pdf337.03 KBJune 7, 2012 - 4:08pm

This paper discusses the application of microwave sensing to turbine airfoil health monitoring. The Meggitt microwave system operates at 6- and 24-GHz and is capable of measuring both tip clearance and the time of arrival of blade tips, i.e. tip-timing. Because it can reliably operate in the hot section of the turbine, the microwave-based system provides an advantage over some of the existing eddy-current based systems. The monitoring of blade tip arrival and clearance pattern is useful for detecting abnormal blade behavior due to structural damage. Such a sensing system can also be used in actively maintaining optimal blade-to-casing clearance, thereby enhancing turbine efficiency. This brief paper presents blade pattern monitoring based on microwave measurements. First, a laboratory study shows the ability of the system to consistency measure tip clearance pattern. Then, tip clearance pattern measurements from a real engine test are presented. While this paper presents results from sensing system testing on tip clearance, it is expected that this study will be carried forward in the next phase to demonstrating tip-timing measurement and further, to show how such as system can form the basis for a more comprehensive health management system.

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Submission Keywords: 
gas turbines
diagnostics and prognostics
Blade Health Monitoring
Microwave sensing
Submission Topic Areas: 
Health management system design and engineering
Industrial applications
Structural health monitoring
Verification and validation
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