Lubrication Characteristics Of Flexure Pivot Tilting Pad Journal Bearing

Tilting pad bearings are widely used in large-scale rotary machines due to its excellent stability.The rigid pivot of a conventional tilting pad bearing is replaced by a flexure pivot that can generate deformation in the flexure pivot tilting pad bearing.The tilting pad of the flexure pivot tilting pad bearing is connected to the bearing housing by the flexure pivot.By eliminating the high contact stress and wear of the pivot,the excellent stability of the flexure pivot tilting pad bearing is improved.Moreover,the lubricating performance of the flexure pivot tilting pad bearing and the dynamic behavior of the supported rotor system are studied in this paper.The main contents are as follows:1.The structural characteristics of the flexure pivot are analyzed using the Castigliano’s theorem and the micro unit method,and the influence of the length and thickness of the flexure pivot on the structural stiffness of the two types of pivot is analyzed.The maximum stress experienced by the flexure pivot at the maximum inclination of the bearing is calculated by the finite element method.2.A calculation model for the flexure pivot tilting pad bearing is established.By using the PDE toolbox,the static Reynolds equation is solved to study the performance of the bearing.The influence of journal speed and eccentricity on the static performance of the bearing is analyzed and compared for the rigid and flexure pivots.3.By using the partial derivative method,the dynamic Reynolds equation of hydrodynamic lubrication is solved.By combining with rotational stiffness of the flexure pivot,a numerical method is proposed to calculate the dynamic stiffness and damping coefficient of the flexure pivot tilting pad bearing with the same frequency disturbance of the bearing bush and the journal.The dynamic coefficient of the bearing is solved based on the small disturbance of the journal and the same frequency disturbance of the bearing bush and the journal.Moreover,the influence of bearing parameters such as preload,width-to-diameter ratio,and journal disturbance frequency on bearing dynamic performance is investigated.4.A dynamic model for the flexure pivot tilting pad bearing-rotor system is established,the dynamics equation of the system is solved by the Newmark method.The unbalance response of the flexure pivot tilting pad bearing-rotor system is analyzed using the time series,Poincare map and trajectory diagram.The above research provides a theoretical basis for the design and application of flexure pivot tilting pad bearings.