Calculating bending vibrations of main axial mine fan rotor shaft

详细

The article presents a calculation procedure for critical rotary speed of an axial main mine fan rotor. The calculations are made for fan model VO-21. The suppositions that make the calculations simpler without considerable errors of the results are evaluated. The calculations use the finite element method and ANSYS software. The critical rotary speeds are determined from the Campbell diagrams plotted for the estimates with and without regard for the stiffness of the bearing assemblies of the rotor. The effect exerted by the rotor bearing assembly stiffness and by the gyroscopic moment of the fan impeller on the frequency of free bending vibrations of the rotor shaft under direct and back precession is illustrated. The estimated critical rotary speeds are compared with the analytical data obtained based on discrete two-mass models. For the preliminary engineering estimation, it is possible to use a discrete two-mass model of the fan rotor without regard for the yielding of the bearing assemblies and for the influence of the gyroscopic model; in the design model, it is required to replace the transmission shaft by the point mass. The calculation error will not exceed 7%.