Whirling Response and Stability of Flexibly Mounted, Ring-Type Flywheel Systems.

摘要

The scarcity and rising cost of pertroleum have motivated international interest in developing hybrid automobiles using flywheels for mechanical energy storage. Rim-type composite-material flywheels are promising designs for such developments. These flywheels significantly differ from turbine/compressor systems in two respects. First, the flywheel rim attachment to its hub is very flexible, for both translation and tilting. Secondly, these flexibilities depend upon rotational speed through centrifugal stiffening. In this investigation, free whirling, stability, and forced whirling are examined for these flywheel systems. The numerical results presented here are most directly applicable to the Sandia single-rim systems currently under development. However, the present analyses can be extended to other flywheel designs within the broad category of the rim type. In the free-whirling analysis, predicted critical speeds are encountered in the design operating speed range. Practical ways to increase such critical speeds are suggested. Effects of material internal damping on the stability of the system are incorporated through adopting complex moduli in the formulation. It is found that the adverse effect of internal damping on the onset of instability can be overcome by providing an adequate external damper up to a considerably high speed.