Numerical Simulation of Nonlinear Oil Film Forces ofTilting‐Pad Guide Bearing in Large Hydro‐unit

Abstract

A new numerical method is proposed for predicting the nonlinearity of tilting-pad guide bearing oilfilm force in the rotor-bearing system in a large hydro-unit. Nonlinear displacement and velocity of the journal center, as well as nonlinear tilting angles and angular velocities of the pads in non-stationary Reynolds equation are taken into account. This method is also suited for other small rotor-bearing system. As an example, the response due to a momentarily created unbalance is Calculated. The nonlinear motion patterns of the pad and journal whirling orbit are obtained. Finally, the nonlinear orbit is compared to the linear one that could be calculated from linear stiffness and damping coefficients. It is shown that there are important differences between those two orbits and that the nonlinear simulation is more accurate.

Approximation of Non-Linear Rotor Dynamic Resonance Behavior of Vertically Aligned Hydro-Units Guided by Tilting-Pad Bearings

“…This enables the calculation of the Reynolds equation based on relative movement between journal and pads. For consideration of the pad inertia the equations of motions must be solved [2][3][4][5][6]. Theoretical investigations of large hydro units indicate that the shaft orbit is nearly circular [3][4][5][6].…”

Dynamic Model for Hydro-Turbine Generator Units Based on a Database Method for Guide Bearings

“…The methods mentioned in previous literature may be classified into the following two categories: a) Making some assumptions such as misalignment and preload, then the linear dynamic coefficients could be used [5]. b) Iteratively solve the Reynolds equation with numerical method in a step by step way until the solution is accurate enough [6,7]. Method a) is suitable for a certain condition like natural frequency analysis or dynamic response of steady-state analysis, but it might be oversimplified for the dynamic response of transient analysis.…”