Dual Clearance Squeeze Film Damper for High Load Conditions

Squeeze film dampers are widely used to control vibrations in aircraft turbine engines and other rotating machinery. However, if shaft unbalance rises ap-preciably above the design value {e.g., due to a turbine blade loss), a conventional squeeze film will be overloaded, and will no longer be effective in controlling vibration amplitudes and bearing forces. This paper describes a new damper concept characterized by two oil films. Under normal conditions, only one low-clearance film is active, allowing precise location of the shaft centerline. Under high unbalance conditions, both films are active, controlling shaft vibration in a near-optimum manner, and allowing continued operation until a safe shutdown can be made