Effect of SFD on rubbing-induced vibration characteristics in dual-rotor-blade-casing system

In a dual-rotor (DR)-blade-casing system, the squeeze film damper (SFD) plays a crucial role in vibration suppression to reduce the vibration level. This paper investigates the impact of SFD on the vibration responses, specifically considering blade-casing rubbing. The Timoshenko beam element is employed to simulate the casing and rotor, while the blade and disk are established using the lumped-mass element. A dynamic model of the DR-blade-casing system with SFD is then developed, incorporating the effects of rubbing. The influence of parameters such as unbalance and blade-casing clearance on the dynamic response is analyzed for systems with and without SFD. The results indicate that SFD effectively reduces the amplitude of the characteristic frequency corresponding to 4-blade rubbing. Additionally, the rubbing fault also induces the combined frequencies between rotating frequencies, integer frequencies, and fractional frequencies. These findings offer valuable insights for fault diagnosis and aero-engine system design.