ROTORDYNAMIC EVALUATION OF AN ADVANCED MULTISQUEEZE FILM DAMPER IMBALANCE RESPONSE AND BLADE-LOSS SIMULATION

In this paper results of rotordynamic response and transient tests of a novel, high load squeeze film damper design are presented. The spira l foil multisqueeze film damper has been previously shown to provide t wo to fourfold or larger increases in damping levels without resorting to significantly decreased damper clearances or increased lengths. By operating with a total clearance of approximately twice conventional designs, the nonlinearities associated with high-eccentricity operatio n are avoided. Rotordynamic tests with a dual squeeze film configurati on were completed. As a part of the overall testing program, a flexibl e rotor system was subjected to high steady-state imbalance levels and transient simulated blade-loss events for up to 0.254 mm (0.01 in.) m ass c. g. offset or 180 g-cm (2.5 oz-in.) imbalance. The spiral foil m ultisqueeze film damper demonstrated that the steady-state imbalance a nd simulated blade-loss transient response of a flexible rotor operati ng above its first bending critical speed could be readily controlled. Rotor system imbalance sensitivity and logarithmic decrement are pres ented showing the characteristics of the system with the damper instal led. The ability to accommodate high steady-state and transient imbala nce conditions make this damper well suited to a wide range of rotatin g machinery, including aircraft gas turbine engines.