Stability behaviour of finite MHD journal bearings

The instability of a rigid rotor supported on MHD journal bearings under the influence of an axial magnetic field and a radial electric field is theoretically analysed in this paper. The MHD Reynold's equation is solved by using the finite element method and stiffness and damping coefficients are obtained. The stability is determined by Routh's criteria. The analysis reveals that the threshold of instability is extended with low values of dimensionless currents at which the load carrying capacities are relatively low. For a bearing with length equal to diameter operating at an eccentricity ratio of 0.6, and Hartmann number of 2, the threshold speed increases by 11% for a dimensionless current of -1, while there is decrease of 18% when the dimensionless current is -5, when compared with the hydrodynamic case. © 1977.