Nonlinear Prediction of Rotordynamic Coefficients For a Hydrodynamic Journal Bearing

Abstract

In the analysis of hydrodynamic journal bearings, linearizedgiven operating conditions, these coeficients vary along the locus strffness and damping coeficients are widely used for the evaluaof the orbital response, and are not valid at large amplitudes (40% tion of stability and dynamic response characteristics. Under of the bearing clearance) of the journal motion. The time history of journal bearing motion for large vibrations is accurarely prePresented at the 56th Annual Meeting Orlando, Florida dicted herein using nonlinear (time-transient) analysis. This Review led by Alan earized coeficients and presents the significance of variation of bp. Bije b.. , BVd 1ld b.. , B.. 1/8 118 C D fX! f,. FX, F, fd, Fd h, H k i p Kije k.. , KVd lid kij8, Kijg nal L m, M MI Ob, 0, P. p pi R r, 7-w. w .r, y, x, y= damping coefficients evaluated at equilibrium position, Ns/m; Bije = bijeCo/w, i, j = x, y = damping coefficients evaluated for the journal orbit, Ns/m; Bijd = bijdCo/w, i j = X, y = damping coefficients evaluated along the locus of the journal orbit, Ns/m; Bijg = bij,Cw/w, i, j = x, y = radial clearance, m =journal diameter, m = bearing forces along vertical and horizontal directions, N; F, = f , h o (~/ c )~ RL, F, = ~D~( R / c )~R L = dynamic force of excitation, N; Fd = fdrnco2 = oil film thickness, m; H = h/C = stiffness coefficients evaluated at the equilibrium position, N/rn K.. = kijeC/w, i, j = x, y Ye = stiffness coefficients evaluated for the journal orbit, Nlrn; K.. I J~ = k . . C / w , i , j = x , y a~d = stiffness coefficients evaluated along the locus of the jour-' trajectory, N/m; Kijg =kijgC/w, i, j = x, y = width of the bearing, m = rotor mass, kg; M = mcw2/w = inverse of mass parameter, MI = 1/M = bearing and journal centers respectively = pressure in the oil film, ~/ m ' ; P = p/qw(R/~)2 = non-dimensional pressure gradients for finite bearing; j = x, y. i. P =journal radius, rn = time, sec; T = tap = static load, N; W = W/I~~(R/C)' RL = vertical and horizontal co-ordinates with respect to bearing center, m; X = x/C, Y = y/C a II e 0 0 s OP R = non-dimensional journal center displacement and velocity in x-direction = non-dimensional journal center displacement and velocity in y-direction = modified non-dimensional journal center displacement and velocity in x-direction = modified non-dimensional journal center displacement and velocity in y-direction = co-ordinate along the axial direction, m; Z = zJL = angle of orientation of dynamic force with respect to horizontal direction = oil viscosity, ~s / m~ = angular coordinate measured from the vertical load direction =journal angular velocity, rad/s = speed parameter; o, = WE = angular velocity of whirl = whirl ratio, ado e = forces or dynamic coefficients calculated with reference to equilibrium position d = forces or dynamic coefficients calculated for the journal orbit g = forces or dynamic coefficients calculated along the locus of the journal orbit m = maximum value of perturbation displacements and velocities in a journal orbit o = at equilibri...

Investigation of the Stability of a 2-DOF Rotor-Hydrodynamic Bearing System Considering Thermal Effects

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Prediction of nonlinear dynamic coefficients of tilting-pad journal bearings with pad perturbation

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