Aeroelastic Flutter of a Flexible Disk Rotating in an Enclosed Compressible Fluid

The aeroelastic stability of a thin, flexible disk rotating in an enclosed compressible fluid is investigated analytically through a discretization of the field equations of a rotating Kirchhoff plate coupled to the acoustic oscillations of the surrounding fluid. The discretization procedure exploits Green’s theorem and exposes two different gyroscopic effects underpinning the coupled system dynamics: one describes the gyroscopic coupling between the disk and acoustic oscillations, and another arises from the disk rotation. The discretized dynamical system is cast in the compact form of a classical gyroscopic system and acoustic and disk mode coupling rules are derived. Effects of eigenvalue veering of structure and acoustic dominated modes are investigated in detail. For the undamped system, coupled structure-acoustic traveling waves can destabilize through mode coalescence leading to flutter instability. Regions in parameter space are identified where structure-acoustic traveling waves of specific wave numbers destabilize. The results are expected to be relevant for the design of high speed, low vibration, low noise hard disk drives and optical data storage systems.