Abstract Hydrodynamic journal bearings are used in many applications which involve high speeds and loads. However, they susceptible to oil whirl instability, may cause bearing failure. In this work, a flexible Jeffcott rotor supported by two identical is investigate the stability bifurcations of system. Since closed form for finite forces not exist, nonlinear stiffness damping coefficients repr...

In this paper, two kinds of vibrations are considered for a composite Timoshenko rotor: longitudinal-torsional vibration and two plane transverse one. The kinetic and potential energies and virtual work due to the gyroscopic effects are calculated and the set of six governing equations and boundary conditions are derived using Hamilton principle. Differential quadrature method (DQM) is used as ...

The performance of Vector Controlled Induction Motor drive depends on the accuracy of rotor resistance which will vary with temperature and frequency. The MRAS approach using reactive power and flux as a state variable for rotor resistance estimation makes MRAS computationally simpler and easy to design. In this paper, Rotor Flux based MRAS (RF-MRAS) and Reactive Power based MRAS (RP-MRAS) for ...

Gas bearings have been widely applied to high-speed rotating machines due their low friction and high rotational speed advantages. Nevertheless, gas lubrication is viscosity compressible. It causes the bearing-rotor system easy produce self-excited vibration, which leads instability of rotor hinders increase speed. necessary study nonlinear behaviors aerostatic vibration system, especially cons...

Among all kinds of journal bearings, the tilting pad bearing has characteristics high stability. In order to further reduce vibration and improve stability rotor-bearing systems, a novel double layers flexible support (DL-FSTPB) is presented in this paper. The utilizes two springs, which have different functions. offset springs control swing angle ensure formation convergent oil film, symmetric...

Stable rotor levitation is a challenge for rotational gyroscopes (magnetically suspended gyroscopes (MSG) and electrostatically suspended gyroscopes (ESG)) with a ring- or disk-shaped rotor, which restricts further improvement of gyroscope performance. In addition, complicated pick-up circuits and feedback control electronics propose high requirement on fabrication technology. In the proposed g...

This paper analyzes an induction motor with high temperature superconducter (HTS) coated slotted solid rotor. By slotting the solid rotor, the electromagnetic torque near synchronous speed will increase but the starting torque will decrease. To improve starting torque, rotor slots are coated with HTS materials. Using HTS material vary the rotor resistance to great extends in starting step and t...

SUMMARY Electromagnetic field theory is applied to the analysis of performance of an induction-motor rotor when it is exposed to a rotating magnetic field of constant amplitude. An idealized model of the rotor is taken and the analysis is simplified by the application of the concept of wave impedance. The model rotor is capable of simulating the effects of tooth-top and zigzag leakage fluxes, b...