Vibro-acoustic characteristics of gear-rotor-bearing coupled system under multi-source excitation

Abstract

With the development of machinery toward high speed, high power, and high reliability, the vibration and noise problems of gearboxes become more prominent. The vibro-acoustic characteristics of gear-rotor-bearing coupled system are difficult to be characterized by the simple gear transmission system. This paper concentrated on modeling an improved dynamic model of gear-rotor-bearing system under multi-source excitation. The initial bending of shaft, precession effect, and gear eccentricity were included in the model to calculate the dynamic response. An extended computational method for predicting the radiation noise of a gearbox was developed. The distribution of the sound pressure around the gearbox was obtained by combining the finite element vibration analysis and boundary element noise analysis. Experimental vibration and noise measurements from a simplified gearbox confirmed the simulation results. The influences of precession effect on dynamic response and radiated noise of the gearbox were investigated. Results show that with the increase of input speed, the peak speeds of the system dynamic load increase and the resonance region shifts. The resonance regions of each field point of the gearbox are enlarged, and the noise is enhanced obviously. The results provide a theoretical basis for the further development of high-quality silent gearboxes.

Using a microphone to perform technical condition vibroacoustic diagnostics of a gas turbine engine’s bearing supports

“…An equally important advantage of a technical microphone is its low sensitivity to changes in the vibration vector. A change in the vibration vector may occur due to the precession of the rotor [7], [8]. In the presence of unbalanced forces, the rotating rotor can cause bending of the shaft axis and displacement of its center of mass relative to the centers of the bearings, which leads to a change in the vibration vector.…”