HCF Detection

Modern turbine engines are making increasing use of the blisk or integrally bladed rotor (IBR). One benefit of using blisks is the reduced weight required to achieve the rotors function. Because a blisk is a single, continuous piece of material there is no decoupling of vibrational energy between the blades and the disk at the center of the rotor. As a result, vibrations can be transferred from one blade through the disk to other blades, setting up vibratory modes of the entire rotor. During the course of operation the blades of a blisk are altered by erosion, fatigue, and FOD. In the case of more significant blade damage the blade may need to be blended to restore its strength. These changes can result in rotor mistuning, allowing for more damaging vibratory modes to be supported in the rotor, leading to high cycle fatigue and ultimately rotor failure. Prime, along with our team partners, will continue to refine the FOCIS based technology to detect and characterize the vibrations of the rotor blades. This will be done by expanding the FOCIS probes native ability to perform time of arrival measurements. In the proposed configuration, a multi-beam variant of the FOCIS probe will be developed allowing for simultaneous monitoring of a blades motion at multiple locations.