Resonant blade response in turbine rotor spin tests using a laser-light probe non-intrusive measurement system

• Main Author: Mansisidor, Michael R.
• Other Authors: Shreeve, Raymond P.
• Published: Monterey, California. Naval Postgraduate School 2012
• Online Access: http://hdl.handle.net/10945/5982

Approved for public release; distribution is unlimited. === Procedures to qualify turbo-machinery components for a designed lifetime free of high cycle fatigue (HCF) failures have not yet evolved. As part of an initiative to address this issue, in the present study, laser-light probes were used in a Non- Intrusive Measurement System (NSMS) to measure the unsteady deflections created in the blades of a second-stage turbine rotor in an evacuated spin pit. Air-jet and eddy-current excitation (ECE) methods were used to stimulate blade resonance. The NSMS was calibrated directly to gauge measurements of strain, and testing was conducted toward three additional goals; assessing the effectiveness of an advanced internal damping system; attaining higher excitation amplitudes with ECE by silver plating blades, and improving the repeatability of resonance data by adding plastic inserts between the fir-tree blade roots and the disk. It was concluded that the ability of NSMS to record the response of all blades is key to understanding the rotor system behavior and quantifying the statistical variability between blades.