Stability and sensitivity analysis of the bending-torsional coupled vibration with the arcuate whirl of hydro-turbine generator unit

The vibrational stability and the shafting vibration sensitivity to some parameters of the unbalanced rotor bending-torsional coupling vibration of the hydro-turbine generator unit (HTGU) with the arcuate whirl were investigated in this study. First, a novel mathematical model of the unbalanced rotor bending-torsional coupling vibration considering the arcu-ate whirl of the shafting for the HTGU was proposed. Second, the vibrational stability of the shafting was studied using the phase trajectory, Poincare map, and frequency spectrum. Third, the shafting vibration sensitivity to some parameters was observed using the parameter bifurcation diagrams. Some shafting vibration phenomena were investigated by comparing the dynamic characteristics of three models, and the phenomena showed that the vibration amplitude of the hydro-turbine runner and generator increased, the torsional vibration angle of the spindle decreased, the generator vibration and the torsional vibration of the spindle sensitivity range to the hydro-turbine runner mass eccentricity changed, and the angular speed that mutates the dynamic vibration characteristic of the HTGU decreased when considering the arcuate whirl. The shafting vibration became stable, but the hydro turbine runner vibration sensitivity range to the generator mass eccentricity and the generator vibration sensitivity range to the hydro-turbine runner mass eccentricity changed when considering the torsional vibration of the spindle. The vibrations of the generator and hydro-turbine runner are sensitive to the torsional damping coefficient in some ranges, the vibrations of the hydro-turbine runner and the spindle are sensitive to the generator mass eccentricity in some ranges, and the vibrations of the generator and the spindle are sensitive to the hydro-turbine runner mass eccentricity in some ranges. (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the vibrational stability and the sensitivity of shafting vibration to parameters of the unbalanced rotor bending-torsional coupling vibration of a hydro-turbine generator unit with arcuate whirl. A novel mathematical model was proposed, and the vibrational stability and sensitivity analysis were conducted through phase trajectory, Poincare map, frequency spectrum, and parameter bifurcation diagrams. The results showed that considering arcuate whirl led to changes in the vibration characteristics of the system and the sensitivity of vibrations to various parameters.