EXPERIMENTAL AND ANALYTICAL INVESTIGATION OF HYBRID SQUEEZE FILM DAMPERS

A new concept for actively controlling high-speed rotating machinery i s investigated both analyically and experimentally. The controlling me chanism consists of a hybrid squeeze film damper (patent pending) that can be adaptively controlled to change its characteristics according to the instructions of a controller. In an extreme case the hybrid dam per can act as a long damper, which is shown to be effective in reduci ng the amplitude of vibration of rotating machinery. In the other extr eme the hybrid damper acts as a short damper, which is shown to be eff ective in reducing the force transmitted to the support. In the long d amper configuration the oil flow is circumferential, while in the shor t damper configuration the oil flow is predominantly axial. The hybrid damper is designed to operate in either the short or the long damper configuration by controlling the positions of two movable sealing ring s. The hybrid damper was tested on a Bently Nevada Rotor Kit and it is shown experimentally that the long damper configuration is extremely efficient at controlling the amplitude of vibration and the short damp er configuration reduces the force transmitted to the support.