A GAS-OPERATED BEARING DAMPER FOR TURBOMACHINERY

A gas-operated bearing damper for turbomachinery has been designed, an alyzed, and experimentally investigated in the laboratory. The damper utilizes air bled off from the compressor to power an actuator through orifices with area modulated by the vibratory displacement at the bea ring support. The design objective for this passive device is to make the actuating dynamic gas pressure phase lead the vibratory displaceme nt by 90 deg. Several variations of the basic concept have been tested . An analysis was performed to guide the experiments. All of the desig ns tested to date can produce positive damping, and one particular des ign has produced a damping coefficient of 87.56 N-s/m (50 lb-sec/in.) with a power penalty of 5.2 kW (7 hp) at 310 KPa (45 psi). This design was installed on a laboratory rotor with flexibly supported ball bear ings, and significant damping of the critical speed response was demon strated. The experimental results to date suggest that further researc h can produce significant improvements in performance, and the device appears to be especially adaptable to high-temperature applications fo r aircraft engines.