Research on Dynamic and Static Characteristics of Air Floating Foil Bearing of High Speed Fan Based on Fluid Domain Simulation
The characteristics of air bearing have a significant impact on the stability of high-speed fan rotors,and the calculation of static and dynamic characteristics of air bearing is the basis for accurately obtaining the unstable speed of the rotor system.A physical model of air bearing and corresponding fluid domain model was established,by setting the parame-ters of air bearing under working conditions,the distribution of fluid domain of air bearing under working conditions was simulated.By adjusting the axis position,the axis position under standard working conditions was found,and the static char-acteristic calculation of air bearing was achieved.On the basis of the results of static characteristics calculation,the journal was subjected to disturbances of the same frequency,and the fluid domain distribution was simulated to obtain the force distribution of the journal under the given disturbance.The stiffness and damping coefficients corresponding to the air bear-ing were solved based on the changes in force,and the calculation of the dynamic characteristics of the air bearing was achieved.The results indicate that as the rotational speed continues to increase,the stable axis position will gradually ap-proach the center of the air floating foil bearing.With the increase of speed within a certain operating speed range,the di-rect stiffness coefficient of the bearing decreases,while the direct damping coefficient increases after reaching a low value within the operating speed range.This provides a theoretical basis for conducting research on rotor subsystem dynamics by analyzing the variation between the characteristic coefficient of the air bearing and the speed.
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