Application of Microwave Sensing to Blade Health Monitoring



David Kwapisz Michaël Hafner Ravi Rajamani


This paper discusses the application of microwave sensing to turbine airfoil health monitoring. The proposed microwave system operates at 6- and 24-GHz and is applicable to both blade tip-clearance and blade tip-timing measurements. One of the main advantages of microwave systems, compared to other technology such as capacitive or eddy current, is that it can be installed for long term operations in the harsh environment of the first turbine stages. The monitoring of blade tip-timing and tip-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 paper presents blade tip-clearance pattern monitoring based on microwave measurements. First, a laboratory study shows the ability of the system to consistently measure tip clearance pattern. Then tip clearance pattern measurements from a real engine test are presented. While this paper presents results from system testing on tip clearance, it is expected that this study will be carried forward in the next phase to demonstrate tip-timing measurement and further, to show how such as system can form the basis for a more comprehensive health management system.

How to Cite

Kwapisz, D., Hafner, M., & Rajamani, R. (2012). Application of Microwave Sensing to Blade Health Monitoring. PHM Society European Conference, 1(1).
Abstract 60 | PDF Downloads 92



gas turbines, diagnostics and prognostics, Blade Health Monitoring, Microwave sensing, clearance

Dyke, J. (2011). Modeling behaviour of damaged turbine blades for engine health diagnostics and prognostics. Master thesis, University of Ottawa, Ottawa, Canada.
Flotow, A., Mercadal, M., & Tappert, P. (2000). Health monitoring and prognostics of blades and disks with blade tip sensors. Aerospace Conference Proceedings, IEEE, Mar 18-25, Big Sky, MT, USA.
Hess, A., Frith, P., & Suarez E. (2006). Challenges, issues, and lessons learned implementing prognostics for propulsion systems. Proceedings of ASME Turbo Expo 2006, May 8-11, Barcelona, Spain.
Hess, A. (2007). Prognostics and health management: The cornerstone of autonomic logistics. (Downloaded from
Holst, T. A. (2005). Analysis of spatial filtering in phase-based microwave measurements of turbine blade tips” Master’s thesis, Georgia Institute of Technology, Atlanta, GA, USA.
Kwapisz, D., Hafner, M., & Queloz, S. (2010). Calibration and characterization of a CW radar for blade tip clearance measurement. Proceedings of the 7th Euro-pean Radar Conference, September 30 - October 1, Paris, France.
Kwapisz, D., Hafner, M., Spitsyn, V., Mykhaylov, A., Berezhnoy, V. (2011). Test and validation of a microwave tip clearance sensor on a 25MW gas turbine engine. Proceedings of the XVI International Congress of Propulsion Engineering, September 14-19, Rybache, Ukraine.
Martin R., Forry, D., Maier, S., & Hansen, C. (2011). GE’s Next 7FA Gas Turbine “Test and Validation” (Downloaded from multimedia/_files/downloads/GEA18457A_7FA_GI_7-27-11_r1.pdf)
SAE (2012). Airfoil diagnostics with blade tip sensors for operating turbomachinery, SAE Aerospace Information Report, AIR5136, Sep 2012.
Woike, M. R., Abdul-Aziz, A., Bencic, T. J. (2010). A microwave blade tip clearance sensor for propulsion health monitoring, AIAA-2010-3308. (Downloaded from gov/20100025863_2010028113.pdf)
Zielinski, M., Ziller, G. (2005). Noncontact blade vibration measurement system for aero engine application; International Symposium of Air Breathing Engines, September 4-9, Munich, Germany.
Technical Papers