The effectiveness of an advanced Hybrid Squeeze Film Damper(HSFD)without the retainer springs on suppressing the nonsynchronous response of the rotor system was studied theoretically.A flexible rotor supported on the orifice-compensated HSFD is taken as an example.It is shown that the HSFD is able not only to improve obviously the highly nonlinear behaviours of the conventional squeeze film dampers

but also to enhance its capability of nonsynchronous response suppression greatly.