HSFD-Mounted Rotor-Bearing System Lubricated with Couple Stress Fluid with Hydraulic Control

The hybrid squeeze-film damper bearing lubricated with couple stress fluid is proposed in this paper. The pressure distribution and the dynamics of a rigid rotor supported by such bearing are studied. Numerical results show that, due to the nonlinear factors of lubricant film force, the trajectory of the rotor demonstrates a complex dynamics with rotational speed ratio s. Poincare maps, and bifurcation diagrams are used to analyze the behavior of the rotor trajectory in the horizontal and vertical directions at s=6.0. The maximum Lyapunov exponent is used to determine if the system is in a state of chaotic motion. Numerical results show that the maximum Lyapunov exponent of this system is positive at the non-dimensional speed ratio s=6.0, which indicate that the rotor trajectory is chaotic under such operation condition. In order to avoid the nonsynchronous chaotic vibrations, an increased proportional gain k(p) = 0.1 is applied to control this system. It is shown that the rotor trajectory will leave chaotic motion to periodic motion in the steady state under control action.