Instantaneous Angular Speed Estimation using Acoustic Emission in Gas Foil Bearings

The instantaneous angular speed (IAS) is a vital state variable of rotating systems, giving insight into the current function of the system and valuable information for condition monitoring algorithms. In this work, we demonstrate that it is possible to estimate the rotor’s IAS from acoustic emission signals (AE) recorded in a gas foil bearing. To do so, we record AE, acceleration, and a reference IAS simultaneously before applying two IAS estimation methods to both signals. Their results are then compared to the reference and among each other. The estimated IAS based on the AE envelope signal was slightly more accurate than the results based on the typically used acceleration signal. However, subharmonic vibrations, which often cause difficulties estimating the IAS, were also more prevalent in the AE envelope. These findings suggest that AE-based algorithms may be able to estimate the IAS from their underlying data without additional sensors in the future.