Session: 28 - 06: Experimental Techniques and Validation in Turbomachinery

Submission Number: 179333

Experimental Modal Testing of Rotating Disks via Low-Speed Imaging 

Monitoring the vibrations of rotating components is crucial for maintaining the structural integrity of turbomachinery. This study presents an experimental methodology for the dynamic characterization of rotating bladed disks (blisks) using digital image correlation (DIC) with low-speed, high-resolution cameras. Synchronous vibrations of the blisk were excited on a rotating test bench using permanent magnets, and the excitation system is described in detail. The cameras captured both rotational and vibrational motions, necessitating rigid-body motion compensation to isolate the structural dynamics. An algorithm was developed to perform this compensation while mitigating cumulative errors.

Due to the limited frame rate of the cameras, the acquired vibration data were inherently downsampled. To address this limitation, a bandpass reconstruction algorithm was implemented to recover high-frequency information from the downsampled measurements. A dedicated postprocessing algorithm was also introduced to accurately reconstruct the target response under frequency-band-limited excitation. This reconstruction is valid under two conditions: the sampling frequency must be at least twice the signal bandwidth, and the ratio between the upper frequency limit and the bandwidth must be an integer value.

The proposed methodology enables accurate identification of resonance frequencies and modal shapes within the frequency band of interest. Experimental validation on a simplified rotating blisk confirms the effectiveness of the approach as a non-contact, low-cost, and versatile tool for high-frequency vibration analysis of rotating blisks.

Presenting Author: Alessandra Cesaretti Politecnico di Torino

Presenting Author Biography: PhD student

Authors:

Alessandra Cesaretti Politecnico di Torino
Serena Occhipinti Politecnico di Torino
Davide Mastrodicasa Siemens Industry Software NV
Emilio Di Lorenzo Siemens Industry Software NV
Christian M. Firrone Politecnico di Torino
Daniele Botto Politecnico di Torino