Designing of elastic suspension for low-flow tilting-pad journal bearing

Аuthors

Parovay E. F.

Samara National Research University named after Academician S.P. Korolev, 34, Moskovskoye shosse, Samara, 443086, Russia

e-mail: selena_pa@mail.ru

Abstract

Paper is devoted to developing of pad elastic suspension designing methods for pad journal bearing with essentially new action mechanism. Developed bearing is tilting-pad journal bearing operating under oil starvation conditions so it is extremely economical. System state and dynamic stability provides working gap force closure due to tilting pads which are elastically suspended on the material MR insets. Elastically suspended pad journal bearings have the ability to high speeds operation and increased resource. Calculation to determine and optimize the performance of elastic- damping suspension bushings is one of the most important stages of a complex technique of designing these bearings. Elastic suspension material allows pads to turn in the radial direction and to make the best working position. The paper presents the developed mathematical models of working gap — pad — elastic suspension system behavior, created with the purpose of determining the elastic suspension material characteristics, providing bearing optimum operating mode. The mathematical method is developed for determining center of the resultant forces in system working air gap — pad — elastic suspension. The method uses the optimal load value, which is determined by the program calculating results (characteristics of lubricant flow: total pressure distribution along the working gap length). Obtained dependences can be used to optimize the pad geometry and MR characteristics (wire diameter, etc.). Model for determining the optimum characteristics of the elastic suspension material (wire diameter, wire material MR density, load value, etc.) is based on the V.N. Buzitskiy and A.A. Troynikov material MR model and takes into account the design and operational features of the bearing. Optimization of these elastic suspension parameters is a condition of failure bearing operation in mind its low oil flow, supernarrow working gap (from 1-5 mсm) and a mechanism for pad tilting on elastic suspension. On the CFD results basis (oil-flow characteristics, ANSYS CFX) using the developed mathematical models it is possible to determine the required MR characteristics and also the parameters of the MR layer behavior under loading by the pressure in the working gap (ANSYS). Two-dimensional contact model was created for system pad — elastic suspension to determine the strain value. Calculating of material MR stiffness C is based on experimental data. Expression for C is used to set the MR Youngs modulus dependence from the magnitude of MR deformation. The hydrodynamic load W = f (φ) is determined by the results of the flow characteristics calculation (pressure distribution along the length of the working gap). Distributions of radial and equivalent stresses, radial and total displacements (deformation) in the system were obtained. Through construction and investigation of the developed models characteristics the possibility of this technique is extended to the elastic suspension parameters optimization by various criteria. Established complex model of the system working gap — pad — elastic suspension allows to solve problems of associated hydrodynamics, thermal analysis and deformation.

Keywords:

pad, deformation, wire diameter, the mathematical model, metal analogue of rubber (MR), load, performance

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