Auxiliary bearings(ABs)are important backup and safety components in active magnetic bearing(AMB)systems.The performance of ABs significantly affects the reliability,safety,and serviceability of theAMB system and the ...Auxiliary bearings(ABs)are important backup and safety components in active magnetic bearing(AMB)systems.The performance of ABs significantly affects the reliability,safety,and serviceability of theAMB system and the rotating equipment.Research on the dynamic behavior during the touchdown process is crucial for analyzing the severity of the touchdown and the behavior is closely related to the performance of theAB.In this paper,a friction torque coefficient is introduced to evaluate the performance ofAB and the touchdown process is simulated and evaluated with various values of this coefficient with a detailed rotor-AB model of a verticalAMB system.The results show that large friction torque coefficient will result in undesired backward whirl of the rotor and catastrophic large load on the AB.Based on these results,this paper suggests that large friction torque coefficient ofABshould be avoided in practice.展开更多
The problem of steady rotation of a composite sphere located at the centre of a spherical container has been investigated. A composite particle referred to in this paper is a spherical solid core covered with a permea...The problem of steady rotation of a composite sphere located at the centre of a spherical container has been investigated. A composite particle referred to in this paper is a spherical solid core covered with a permeable spherical shell. The Brinkman＇s model for the flow inside the compos- ite sphere and the Stokes equation for the flow in the spheri- cal container were used to study the motion. The torque ex- perienced by the porous spherical particle in the presence of cavity is obtained. The wall correction factor is calculated. In the limiting cases, the analytical solution describing the torque for a porous sphere and for a solid sphere in an un- bounded medium are obtained from the present analysis.展开更多
基金National Key R&D Program of China[2018YFB2000100]the National Science and Technology Major Project of China(2019ZX069).
文摘Auxiliary bearings(ABs)are important backup and safety components in active magnetic bearing(AMB)systems.The performance of ABs significantly affects the reliability,safety,and serviceability of theAMB system and the rotating equipment.Research on the dynamic behavior during the touchdown process is crucial for analyzing the severity of the touchdown and the behavior is closely related to the performance of theAB.In this paper,a friction torque coefficient is introduced to evaluate the performance ofAB and the touchdown process is simulated and evaluated with various values of this coefficient with a detailed rotor-AB model of a verticalAMB system.The results show that large friction torque coefficient will result in undesired backward whirl of the rotor and catastrophic large load on the AB.Based on these results,this paper suggests that large friction torque coefficient ofABshould be avoided in practice.
文摘The problem of steady rotation of a composite sphere located at the centre of a spherical container has been investigated. A composite particle referred to in this paper is a spherical solid core covered with a permeable spherical shell. The Brinkman＇s model for the flow inside the compos- ite sphere and the Stokes equation for the flow in the spheri- cal container were used to study the motion. The torque ex- perienced by the porous spherical particle in the presence of cavity is obtained. The wall correction factor is calculated. In the limiting cases, the analytical solution describing the torque for a porous sphere and for a solid sphere in an un- bounded medium are obtained from the present analysis.
