Bifurcation and nonlinear dynamic analysis of a rigid rotor supported by two-lobe noncircular gas-lubricated journal bearing system

Abstract

This paper presents the study of the dynamic analysis of a rigid rotor supported by a twolobe non-circular gas-lubricated journal bearing. A finite element method has been employed to solve the Reynolds equation in static and dynamical states and the dynamical equations have been solved using Runge-Kutta method. To analyze the behavior of the rotor center in horizontal and vertical directions under the different operating conditions, the dynamic trajectory, the power spectra, the Poincare maps, and the bifurcation diagrams are used. Results of this study indicates that by considering bearing number and rotor mass as the parameters of the system, complex dynamic behavior comprising periodic, KT -periodic, and quasi-periodic responses of the rotor center has occurred.

Flow field calculation and dynamic characteristic analysis of spherical hybrid gas bearings based on passive grid

“…The lubrication analysis model of the spherical helical groove hybrid gas bearings which reflects the pressure field and velocity field distribution, dynamic bearing characteristics and lubrication characteristics of the gas film in the bearing clearance. In the calculation of the fluid has the following assumptions: (1) The lubricating medium is Newton fluid, and the gas viscosity coefficient is constant; (2) There is no heat exchange between the gas and the wall, and the thermal deformation of the bearing and journal is not considered during the rotation; (3) In the direction perpendicular to the thickness of the gas film, the velocity change is neglected, that is the pressure does not change along the gas film thickness; (4) The gas does not have relative sliding on the shaft and bearing surfaces; (5) The wall is assumed to be smooth, without considering the influence of wall roughness and slip boundary.…”

“…Hybrid gas bearings has the nonlinear coupling effect of static pressure and dynamic pressure. The phenomenon of whirl instability and gas film oscillation occurs at high speed, which lead to the failure of bearings and restrict the wide application of gas bearings 4,5 . The dynamic characteristics of the gas film reflect the variation law of the gas film force when the journal deviates from the static equilibrium position and the displacement motion in the vicinity, which has very complex non-linear and stochastic characteristics.…”

Dynamic Analysis of a Motorized Spindle With Externally Pressurized Air Bearings

“…The complete nonlinear equations pertinent to the rotor-bearing system are integrated by numerical methods to obtain the rotor center orbits corresponding to any specified set of geometrical, running, and initial conditions [12]. The orbit method enables both establishment of the stability threshold and prediction of the behavior of the bearing into the instability region [13][14][15][16][17]. However, the orbit method to solve nonlinear equations is slow and less effective than the perturbation method; as such, it will not be considered in this work.…”

Chaotic and dynamic analysis of a flexible rotor supported by ultra short aero-lubricated bearing system

“…Recently, dynamic responses of bearing systems were analyzed and the bifurcation phenomenon and dynamic behavior of rigid rotor supported by noncircular aero-lubricated bearing system were studied by Rashidi et al (2009Rashidi et al ( , 2010. The finite element method and Runge-Kutta method are applied to solve the Reynolds' equation and rotor dynamic equations, respectively.…”