Operational deflection shape measurements on rotating bladed disks with tracking continuous-scanning LDV

The high-speed rotation and complex operational environment of rotating bladed disks make it difficult for traditional contact measurement techniques to achieve effective, non-interfering, and continuous monitoring of their full-field dynamic responses under operational conditions. To address this challenge, this paper proposes and validates a tracking continuous scanning method based on laser Doppler vibrometry (LDV), aiming to achieve accurate reconstruction of their operational deflection shapes. The core of TCSLDV lies in synchronizing the laser beam with the disk rotation while performing continuous scanning along a predefined blade path. A multi-beam setup and a phase-offset strategy enable seamless switching between blades without stopping, allowing for simultaneous measurement of responses on multiple blades and fixed reference points. By employing an operational deflection shape frequency response function (ODS FRF) phase identification scheme, the phase relationships between blades are extracted, facilitating the reconstruction of the overall operational deflection shape (ODS) of the entire rotating bladed disk. Experimental validation on a simple bladed disk at 120 r/min demonstrated the method’s accuracy, showing a high modal assurance criterion (MAC) of 0.98 between the reconstructed ODS and the finite element predicted mode shape. Additional tests at higher rotational speeds confirmed the method’s applicability under operational excitation. This work presents a cost-effective, non-contact, and continuous scanning solution for full-field ODS measurement in rotating environments, offering significant potential for in-situ modal analysis and model validation of rotating machinery.