Abstract: This paper presents an advanced hybrid (combination of hydrostatic and hydrodynamic)squeeze film damper(HSFD)concept which is used to improve the high nonlinearity of conventional hydrodynamic squeeze film dampers (SFD's). Based on the approximation solution of fluid film\|force of the deep recessed HSFD without axial slots, taking an orifice compensated HSFD with four deep recesses for example, the stiffness and damping behavior of HSFD are analysed, and the control ability of HSFD to reduce rotor vibration is studied both theoretically and experimentally with a rigid rotor supported on HSFD. It is shown that HSFD not only can improve significantly the high nonlinearity of fluid film\|force of the SFD and avoid the bistable operations with very large rotor vibration occuring in the SFD system, but also can effectively reduce rotor system vibration, especially for larger rotor unbalance and radial clearance ratio.

Key words: rotor dynamics damper, vibration control