A CHAMBERED POROUS DAMPER FOR ROTOR VIBRATION CONTROL .2. IMBALANCE RESPONSE AND BLADE-LOSS SIMULATION

In this paper, results of experimental rotordynamic evaluations of a n ovel, high load chambered porous damper design are presented. The cham bered porous damper concept was evaluated for gas turbine engine appli cation since this concept avoids the nonlinearities associated with hi gh-eccentricity operation of conventional squeeze film dampers. The ro tordynamic testing was conducted under large steady-state imbalance an d simulated transient bladeloss conditions for up to 0.254 mm (0.01 in .) mass c.g offset or 180 g-cm (2.5 oz-in.) imbalance. The chambered p orous damper demonstrated that the steady-state imbalance and simulate d blade-loss transient response of a flexible rotor operating above it s first bneding critical speed could be readily controlled. Rotor syst em imbalance sensitivity and logarithmic decrement are presented showi ng the characteristics of the system with the damper installed. The ab ility to accommodate high steady-state and transient imbalance conditi ons makes this damper well suited to a wide range of rotating machiner y, including aircraft gas turbine engines.