SBIR-STTR Award

Technology is proposed for in-service detection of airfoil and rotor defects, and of operating conditions that can accelerate them. The technology consists of deterministic signal processing algorithms that fundamentally advance spectrum analyzer technology for extracting torsional vibration signals from operating turbines. Newly patented analytical methods for constant velocity power turbines will be generalized to accommodate the effects of acceleration in high performance aircraft turbines. The resulting technology will continuously extract airfoil and rotor resonances and track their frequency shifts as a means to detect integrity-reducing structural changes in those engine components. The current project will also code the generalized method and test it with data collected during on-going, full-scale compressor tests, with the results being compared with strain gauge data. The resulting technology will provide continuous resonance information for in-flight or ground-based use. In-flight uses include detecting defects and such conditions as airfoil flutter or contamination. Ground-based uses include design, development and testing, including maintenance inspections.

Keywords:
In-Service Defect Maintenance Turbine Airfoil Instrumentation Non-Destructive Design

High Cycle Fatigue (HCF) in turbine engines effects aircraft availability and reliability, and significantly increases life-cycle cossts, most particularly in high performance aircraft. The activities outlined in this Phase II proposal are designed to refine RVM signal processing software demonstrated in Phase I to precisely and quantitatively track blade resonances and detect cracks in variable speed turbines. The goal of continued development and commercialization is an optimized RVM algorithm with in-flight capabilities to detect HCF, HCF-forcing conditions, and other defects in rotating components. The RVM technology will then support on-condition maintenance and potentially will allow control systems to avoid operating conditions that can accelerate HCF. Briefly, RVM processes signals from engine speed sensors to extract multiple modes of rotor component resonances with unprecedented sensitivity, precision and repeatability. RVM detects frequency shifts in these modes due to cracks and other flaws that alter component stiffness. Tracking the modes shifts due to mechanical changes potentially will allow calculation of location and extent of defects, where that is desirable. It is important to note that RVM is of a form that accommodates large, rapid changes in RPM, e.g. due to engine acceleration (hereafter the "variable speed RVM" applications). MTC has a strong history of success in commercialization of vibration monitoring products, with Fortune 500 customers in all major industrial sectors.

Keywords:
In-Service Defect Maintenance Turbine Airfoil Instrumentation Non-Destructive Design