Enhancing the stability of rotating machinery using a lower pad adjustable journal bearing

A lower pad adjustable journal bearing is proposed in this paper. This bearing can adjust the working status of the rotor system by changing the position of the bearing pad and improve the stability of the rotor system. The adjustable bearing structure achieves the function of changing the characteristic parameters of the bearing under continuous operation and makes up for the shortcomings of the traditional fixed-pad bearing. In this paper, the evaluation method of the dynamic characteristics of the adjustable bearing is introduced. The stiffness and damping characteristics of the bearing are calculated by the analytical method. Then, the rotor bearing system model is established using the finite element method. Finally, the dynamic response of the rotor system is solved by Runge–Kutta variable step length integration. The numerical results show that the stability of the system can be improved by reducing the ellipticity of the adjustable bearing when the rotor system crosses the critical speed. The experimental study shows that when the oil film is unstable in the rotor system, the oil film whip is effectively eliminated by reducing the ellipticity, which proves that the adjustable bearing can improve the stability of the rotating machine.