Modal analysis of a rotating pretwisted multi -packet blade system

초록

A modeling method for the modal analysis of a pre-twisted multi-packet blade system undergoing rotational motion is presented in this paper. Blades are idealized as cantilever beams that are fixed to a rotating disc. The stiffness coupling effects between blades due to the flexibilities of the disc and the shroud are modeled with discrete springs. The coupling effect between chordwise and flapwise bending motions is also considered. Hybrid deformation variables are employed to derive the equations of motion. To obtain more general information, the equations of motion are transformed into dimensionless forms in which dimensionless parameters (angular speed, pre-twist angle, hub radius, location and stiffness of the disk spring and the shroud spring) are identified. The effects of the dimensionless parameters and number of packets on the modal characteristics of the rotating pre-twisted multi-packet blade system are investigated with some numerical examples.

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