Shaft-Torsion and Blade-Bending Coupling Vibrations in a Rotor System with Grouped Blades

抄録

This paper discussed the shaft-torsion and blade-bending coupling vibrations of a rotor system, in which the blades were grouped with lacing wires. Massless tension springs were used for modeling the lacing wires. An energy principle in conjunction with the assumed modes method was employed to yield the discrete equations of motion. The natural frequencies and the mode shapes of the system were solved for five- and six-blade cases as examples. Numerical results showed how the natural frequencies varied with the wire stiffness, connecting position, and the rotational speed. The diagrams of the coupling mode shapes and FRF's were drawn. From the results, it was found that lacing wire did not affect the SB (shaft-blades) coupling modes, but the BB (inter-blades) modes were indeed affected by the lacing wire. At moderate range of wire stiffness, the repeated BB modes split into more distinct modes. As expected, increasing the wire stiffness or connecting near outer edge would strengthen the system structure and increasing the natural frequencies of BB modes.