Research On Dynamic Characteristics Of Multi-Disk Rotor Systems Based On Torsional Excitation

The structure of the multi-disk rotor system is more complex. The effect of the torsional excitation or residual shaft bow may lead failure of the rotor system in operation. Recently, a number of researchers have conducted some studies in this field. However, these studies have not yet to be in-depth. In this paper, some studies have been carried out as followed.(1) The torsional excitation expression was improved, and the results of the simulation and the test before and after the torsional excitation improved were compared and analysed, respectively. The results indicate that the simulation is more close to the actual one after improving the torsional excitation expression.(2) Based on the improved torsional excitation expression, the model and the dynamic equation of the multi-disk rotor system were established by considerring the effect of the nonlinear oil film force and the elastic support. The effect of the different nature (nonlinear and transient) torsional excitation to the multi-disk rotor system was studied by simulation and test, respectively. The results indicate that the vibration amplitudes of multi-disk rotor system have no change, and the phenomenon of vibrational equilibrium position downward shift was appeared. Also, the offset of each cross rotor in X direction is less than the one in Y direction, obviously.(3) Based on the improved torsional excitation expression, the transfer model of torsional excitation in multi-disk rotor system was established by considering the effect of the flexible coupling, and the sensitivity matrix of the bearing load to torsional excitation was derivated. The transfer characteristics of different nature (nonlinear and transient) torsional excitation in multi-disk rotor system were studied by simulation and test, respectively. The results indicate that the transfer characteristics of different nature (nonlinear and transient) torsional excitation in multi-disk rotor system in X and Y direction were difference, and with the effect of the same torsional excitation, the sensitivity responses of the bearing load to torsional excitation in X direction and Y direction were difference.(4) The model of the multi-disk rotor system with residual shaft bow was established, and the effect of the residual shaft bow, eccentricity, damping ratio to multi-disk rotor system was simulated and analysed. The feature extraction and signal recognition of the residual shaft bow fault signal were achieved, and the results of the simulation and the test fault signal of residual shaft bow were compared. The test modified equation of the rotor system with residual shaft bow was proposed.(5) Based on the noise reduction methods of wavelet and mathematical morphology, the method of wavelet-morphology was proposed. The signals of the simulation and the test were denoised by the noise reduction methods of mathematical morphology and wavelet-morphology, respectively. The results indicate that the noise reduction method of wavelet-morphology can be well used to denoise the bearing load signals.After the studies in this paper, the effect of torsional excitation to multi-disk rotor system can be well known, and the characteristics of torsional excitation, residual shaft bow fault signal, bearing load signal can be obtained. This paper lays the foundation for suppressing torsional excitation interference, rotor system typical fault diagnosis and improving the efficiency of bearing load signal acquisition.