Analysis of the multiphase lubricating oil effect on the performance of the tilting-pad journal bearing

As heavy industry develops, large amounts of tilting-pad journal bearings are widely used in advanced technology and key equipment. So, it has become a hot research direction to ensure the stable operation of tilting-pad journal bearings by using multiphase lubricating oil. The aim of the present research was to clarify whether using the multiphase lubricating oil has a positive effect on the performance of the bearings. The approach is based on computational multiphase fluid dynamics and finite-element method. Reynolds averaged equations of multiphase flow was applied to computation for improving the accuracy. The change of loading capacity of oil film was studied with computational fluid dynamics simulation under particles added to the lubricating oil. The results indicate that the bearing capacity of bearing increases when the particle content, diameter and density increase. The performance of bearing becomes better when the multiphase lubricating oil is applied in the oil film of bearing. The implications of these results are that the development of multiphase lubricating oil has important practical significances.

Download Full-text

Cooled Pads for Tilting-Pad Journal Bearings

Lubricants ◽

10.3390/lubricants7100092 ◽

2019 ◽

Vol 7 (10) ◽

pp. 92

Author(s):

Steven Chatterton ◽

Paolo Pennacchi ◽

Andrea Vania ◽

Phuoc Vinh Dang

Keyword(s):

Cross Sections ◽

Three Dimensional ◽

Experimental Tests ◽

Journal Bearings ◽

Maximum Temperature ◽

Inlet Temperature ◽

Oil Film ◽

External Cooling ◽

Tilting Pad ◽

Tilting Pad Journal Bearings

Tilting-pad journal bearings (TPJBs) are widely installed in rotating machines owing to their high stability, but some drawbacks can be noted, such as higher cost with respect to cylindrical journal bearings and thermal issues. High temperatures in the pads correspond to low oil-film thicknesses and large thermal deformations in the pads. Therefore, the restriction of the maximum temperature of the bearing is a key aspect for oil-film bearings. The temperature reduction is generally obtained by adopting higher oil inlet flowrates or suitable oil nozzles. In this paper, the idea of using cooled pads with internal channels in which an external cooling fluid is circulated will be applied to a TPJB for the first time. The three-dimensional TEHD model of the TPJB, equipped with a cooled pad, will be introduced, and the results of the numerical simulations will be discussed. Several analyses have been performed in order to investigate the influence of cooling conditions, such as the type, flowrate, inlet temperature and number of cooled pads. Two types of pad geometry with different cross-sections of the cooling circuit, namely, circular and six-square multi-channel sections, have been compared to the reference bearing with solid pads. Simple experimental tests were performed by means of a test rig equipped with a cooled pad bearing obtained with the additive manufacturing process, thus showing the effectiveness of the solution and the agreement with the predictions.

Download Full-text

Performance of Tilting Pad Journal Bearings with the Same Sommerfeld Number

Applied Sciences ◽

10.3390/app10103529 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3529

Author(s):

Sung-Hwa Jeung ◽

Junho Suh ◽

Hyun Sik Yoon

Keyword(s):

Thermal Behavior ◽

Elastic Deformation ◽

Heat Generation ◽

Thermal Deformation ◽

Journal Bearings ◽

Hertzian Contact ◽

Maximum Temperature ◽

Oil Film ◽

Tilting Pad ◽

Tilting Pad Journal Bearings

This paper presents the change of non-dimensional characteristics and thermal behavior of different sized tilting pad journal bearings (TPJBs) with the same Sommerfeld number. A three-dimensional (3D) TPJB numerical model is provided considering the thermo-elastic hydro-dynamic (TEHD) lubrication model with pad thermal-elastic deformation. The pivot stiffness is assumed to be the combination of linear and cubic stiffness based on the Hertzian contact theory. The TPJBs in a configuration of load between pad (LBP) with the same Sommerfeld number having seven different sizes are simulated, and their non-dimensional dynamic and static characteristics and thermal behavior are compared. Pad thermal and elastic deformation are both taken into account. If the changes in lubricant viscosity, thermal deformation, and elastic deformation of journal/pads due to viscous shearing are ignored, the bearings with identical Sommerfeld numbers should show the same performance characteristics. However, the heat generation at the bearing clearance during operation (a) induces a decrease in viscosity and heat transfer to journal/pads and (b) results in a thermal deformation. Furthermore, the elastic deformation of the tilting pads and pivots also affects the bearing dynamic performance. For the same Sommerfeld number, the numerical analyses provide how the viscous shearing and elastic deformation lead to a change in bearing performance. For the small bearings with the same Sommerfeld number, the non-dimensional characteristics did not change significantly, where the heat generation was small being compared to the large sized bearing. The largest change in non-dimensional characteristics occurred when the maximum temperature of the oil film increased by 30 °C or more compared to the lubricant supply temperature. The root cause of the change in the non-dimensional characteristics is the viscous shearing in the oil film, and the thermal deformation of the structures surrounding the oil film acts in combination. These results provide insight into the Sommerfeld number, which can be used for the early stage of bearing design.

Download Full-text

Instability Threshold of a Rigid Rotor-Tilting Pad Journal Bearings System

International Journal of Rotating Machinery ◽

10.1155/s1023621x97000195 ◽

1997 ◽

Vol 3 (3) ◽

pp. 199-213 ◽

Cited By ~ 1

Author(s):

Stefano Pagano ◽

Ernesto Rocca ◽

Michele Russo ◽

Riccardo Russo

Keyword(s):

Differential Equations ◽

Numerical Integration ◽

Equations Of Motion ◽

Journal Bearings ◽

Stable Operation ◽

Rigid Rotor ◽

Tilting Pad ◽

The Stability ◽

Tilting Pad Journal Bearings ◽

Rotor Axis

The stability of a rigid rotor supported on radial tilting pad journal bearings is analysed. This study has been tackled both for small unbalance values by linearising the equations of motion, and also in the case where, because of the high unbalance value, the rotor axis describes orbits with an amplitude such that the system's non-linearity cannot be ignored. In both cases the system's stable operation maps have been obtained and verified through numerical integration of the differential equations of motion.

Download Full-text

Thermal Deformation of Pads in Tilting 5-Pad Journal Bearing

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-63832 ◽

2005 ◽

Author(s):

S. Strzelecki ◽

L. Kusmierz ◽

G. Poniewaz

Keyword(s):

High Speed ◽

Journal Bearing ◽

Journal Bearings ◽

Oil Film ◽

Tilting Pad ◽

Drive Trains ◽

Shaft Misalignment ◽

Tilting Pad Journal Bearings ◽

Turbine Drive ◽

Oil Film Pressure

In high speed compressors and turbine drive trains, the tilting 5-pad journal bearings are applied. Tilting-pad journal bearings are good option because they have very good hydrodynamic stability at high speed and are less sensitive to load direction and shaft misalignment. The paper introduces thermo-elastic deformations of tilting 3-pad journal bearing with asymmetric support of pads and operating at the conditions of adiabatic oil film. The deformations of pads were obtained based on the oil film pressure and temperature distributions. Reynolds, energy, geometry and viscosity equations have been solved numerically on the assumption of aligned orientation of bearing and journal axis and at static equilibrium position of journal.

Download Full-text

Characterization of Five-Pad Tilting-Pad Journal Bearings Using an Original Test-Rig

Volume 1: 23rd Biennial Conference on Mechanical Vibration and Noise, Parts A and B ◽

10.1115/detc2011-48166 ◽

2011 ◽

Author(s):

S. Chatterton ◽

P. Pennacchi ◽

A. Vania ◽

E. Tanzi ◽

R. Ricci

Keyword(s):

Film Thickness ◽

Gas Turbines ◽

Journal Bearings ◽

Fluid Film ◽

Test Rig ◽

Theoretical Evaluation ◽

Oil Film ◽

Tilting Pad ◽

Fluid Film Thickness ◽

Tilting Pad Journal Bearings

Tilting-pad journal bearings are installed with increased frequency owing to their dynamic stability characteristics in several rotating machine applications, typically in high rotating speed cases. This usually happens for new installations in highspeed compressors or during revamping operations of steam and gas turbines for power generation. The selection from a catalogue, or the design of a new bearing, requires the knowledge of the bearing characteristics such as babbitt metal temperatures, fluid-film thickness, load capacity, stiffness and damping coefficients. Temperature and fluid-film thickness are essential for the safety of the bearing. Babbitt metal is subject to creep at high temperatures, as it happens at high speed operations. On the contrary, at low speed or with high loads, oil-film thickness could be too low, resulting in metal to metal contact. Oil-film dynamic coefficients are largely responsible of the dynamic behaviour and of the stability of the rotor-tilting-pad-bearing system. Therefore, the theoretical evaluation and/or the experimental estimation of these coefficients are mandatory in the design phase. The theoretical evaluation of these coefficients for tilting pad journal bearings is difficult due to their complex geometry, boundary and thermal conditions and turbulent flow, whereas an experimental characterization requires a suitable test rig. The paper describes the test rig designed to this purpose and its unusual configuration with respect to other test rigs available in literature. Some preliminary tests performed for the bearing characterization are also shown.

Download Full-text

Nonlinear Dynamic Behaviors of an Imbalance Rotor Supported on Fixed-Tilting Pad Journal Bearings

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.291-294.1941 ◽

2011 ◽

Vol 291-294 ◽

pp. 1941-1951

Author(s):

Xiao Bing Qi ◽

Lei Feng ◽

Yong Fang Zhang ◽

Yan Jun Lu

Keyword(s):

Pressure Distribution ◽

Reynolds Equation ◽

Axial Direction ◽

Journal Bearings ◽

Nonlinear Phenomena ◽

Dynamic Behaviors ◽

Oil Film ◽

Tilting Pad ◽

Field Dynamic ◽

Tilting Pad Journal Bearings

Based on the unsteady Reynolds equation with Reynolds boundary, two-dimensional (2D) Reynolds equation is transformed into one-dimensional (1D) by taking the assumption of parabolic pressure distribution in axial direction in oil film field. Finite difference method was employed to solve 1D Reynolds equation, and the approximate pressure distribution was obtained in oil film field. Dynamic behaviors of a flexible rotor system with fixed-tilting pad journal bearings support were analyzed while the inertia of the pads was taken into consideration in the model. Imbalance responses of a symmetrical rotor-combination journal bearings (fixed-tilting pad journal bearings) system were investigated using Poincaré map and self-adaptive Runge-Kutta method. Numerical results reveal rich and complex nonlinear phenomena, such as periodic, quasi-periodic motion, etc.

Download Full-text

Analysis of the multiphase lubricating oil effect on the performance of the tilting-pad journal bearing

Thermal Science ◽

10.2298/tsci191112092z ◽

2021 ◽

pp. 92-92

Author(s):

Yuchuan Zhu ◽

Zhengyi Jiang ◽

Ling Yan ◽

Yan Li ◽

Fangfang Ai ◽

...

Keyword(s):

Fluid Dynamics ◽

High Speed ◽

Journal Bearing ◽

Lubricating Oil ◽

Loading Capacity ◽

Heavy Load ◽

Oil Film ◽

Tilting Pad ◽

Multiphase Fluid ◽

Tilting Pad Journal Bearing

The multiphase fluid dynamics is used to model the oil film in the tilting-pad journal bearing. Particles are added to the lubricating oil and the change of loading capacity of oil film is studied numerically. The performance of the bearing under high-speed and heavy load are elucidated. The results show that the bearing capacity depends upon concentration, diameter and density of particles.

Download Full-text

On the Simplifications for the Thermal Modeling of Tilting-Pad Journal Bearings Under Thermoelastohydrodynamic Regime

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-68329 ◽

2012 ◽

Cited By ~ 5

Author(s):

Alejandro Cerda Varela ◽

Michel Fillon ◽

Ilmar Ferreira Santos

Keyword(s):

Heat Transfer ◽

Journal Bearing ◽

Journal Bearings ◽

Laminar Regime ◽

Transfer Effects ◽

Oil Film ◽

Tilting Pad ◽

Heat Transfer Effects ◽

Tilting Pad Journal Bearing ◽

Tilting Pad Journal Bearings

The relevance of calculating accurately the oil film temperature build up when modeling tilting-pad journal bearings is well established within the literature on the subject. This work studies the feasibility of using a thermal model for the tilting-pad journal bearing which includes a simplified formulation for inclusion of the heat transfer effects between oil film and pad surface. Such simplified approach becomes necessary when modeling the behavior of tilting-pad journal bearings operating on controllable lubrication regime. Three different simplified heat transfer models are tested, by comparing their results against the ones obtained from an state of the art tilting-pad journal bearing model, where the heat transfer effects are throughly implemented, as well as against some experimental results from the literature. The results obtained show that the validity of the simplified heat transfer models are strongly dependent on the Reynolds number for the oil flow in the bearing. For bearings operating in laminar regime, the decoupling of the oil film energy equation solving procedure, with no heat transfer terms included, with the pad heat conduction problem, where the oil film temperature is applied at the boundary as a Dirichlet condition, showed a good balance between quality of the results, implementation easiness and reduction in calculation time. For bearings on the upper limit of the laminar regime, the calculation of an approximated oil film temperature gradient in the radial direction, as proposed by Knight and Barrett, delivered the best results.

Download Full-text