Influence of new surface micro-structures on the performance behaviours of fluid film tilting pad thrust bearings

2021 ◽  
pp. 095440622110309
Author(s):  
JC Atwal ◽  
RK Pandey
Keyword(s):  
Mass Conservation ◽  
Performance Parameters ◽  
Algebraic Equations ◽  
The Finite Element Method ◽  
Thrust Bearings ◽  
Lubrication Equation ◽  
Tilting Pad ◽  
Minimum Film Thickness ◽  
Newton Raphson ◽  
Micro Structures

Performance parameters such as power loss, minimum film thickness, and maximum oil temperature of the sector-shaped tilting pad thrust bearings employing the new micro-structural geometries on pad surfaces have been investigated. The lubrication equation incorporating the mass-conservation issue is discretized using the finite element method and the solution of resulting algebraic equations is obtained employing a Newton-Schur method. The pad equilibrium in the analysis is established using the Newton-Raphson and Braydon methods. The influence of attributes of micro-structures such as depth, circumferential and radial positioning extents have been explored on the performance behaviours. It is found that with the new micro-structured pad surfaces, the performance parameters significantly improved in comparison to conventional plain and conventional rectangular pocketed pads.

Film Thickness and Friction Investigations in a Fluid Film Thrust Bearing Employing A New Conceived Micro-Texture on Pads

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
J. C. Atwal ◽  
R. K. Pandey
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Mass Conservation ◽  
Fluid Film ◽  
Element Formulation ◽  
Algebraic Equations ◽  
Pocket Depth ◽  
Lubricating Film ◽  
Minimum Film Thickness ◽  
Radial Length

Abstract This paper presents the performance behaviors (coefficient of friction, minimum film thickness, and pressure distributions) of a fluid film thrust bearing using a newly conceived micro-texture on pads. In the numerical investigation, the Reynolds equation has been discretized using the finite element formulation followed by the solution of algebraic equations employing the Fischer-Burmeister-Newton-Schur (FBNS) algorithm, which satisfies the mass-conservation phenomenon arising due to the commencement of cavitation in the lubricating film. The effects of parameters (micro-texture/pocket depth, circumferential/radial length of micro-texture and pocket, etc.) of new texture on the performance behaviors of the thrust bearing have been explored and presented herein for the range of input data. It has been found that the minimum film thickness has increased up to 48%, and the friction coefficient reduced up to 24% in comparison to conventional plain pad case.

A Model for Tilting Pad Thrust Bearings Operating With Reduced Flow Rate – Do Benefits Outweigh Risks?

2021 ◽  
Author(s):  
Rasool Koosha ◽  
Luis San Andrés
Keyword(s):  
Film Thickness ◽  
Flow Rate ◽  
Temperature Rise ◽  
Thrust Bearings ◽  
Flow Reduction ◽  
Tilting Pad ◽  
Minimum Film Thickness ◽  
Nominal Rate ◽  
Thrust Pad ◽  
Reduced Flow

Abstract The literature on tilting pad thrust bearings (TPTB) calls for flow reduction as an effective means to reduce drag power losses as well as oil pumping costs. However, the highest level of flow reduction a bearing can undergo while maintaining reliable operation is a key question that demands comprehensive analysis. This paper implements a model into an existing thermoelasto-hydrodynamic (TEHD) computational analysis tool to deliver load performance predictions for TPTBs operating with reduced flow rates. For bearings supplied with either a reduced flow or an over flow conditions, a sound model for the flow and thermal energy mixing in a feed groove determines the temperature of the lubricant entering a thrust pad. Under a reduced flow condition, the analysis reduces the effective arc length of a wetted pad until matching the available flow. Predicted discharge flow temperature rise and pad subsurface temperature rise from the present model match measurements in the archival literature for an eight-pad bearing supplied with 150% to 25% of the nominal flow rate, i.e., the minimum flow that fully lubricates the bearing pads. A supply flow above nominal rate increases the bearing drag power because the lubricant enters a pad at a lower temperature, and yet has little effect on a thrust pad peak temperature rise or its minimum film thickness. A reduced flow below nominal produces areas lubricant starvation zones, and thus the minimum film thickness substantially decreases while the film and pad’s surface temperature rapidly increase to produce significant thermal crowning of the pad surface. Compared to the bearing lubricated with a nominal rate, a starved flow bearing produces a larger axial stiffness and a lesser damping coefficient. A reduction in drag power with less lubricant supplied brings an immediate energy efficiency improvement to bearing operation. However, sustained long-term operation with overly warm pad temperatures could reduce the reliability of the mechanical element and its ultimate failure.

Numerical Investigations of Various Surface Roughness Parameters on the Performance of Profiled Hydrostatic Thrust Bearing

2005 ◽  
Author(s):  
Kirat Shah ◽  
Robert E. Johnson ◽  
Harish P. Cherukuri
Keyword(s):  
Surface Roughness ◽  
Thrust Bearings ◽  
Lubrication Equation ◽  
Load Carrying ◽  
Minimum Film Thickness ◽  
Order Of Magnitude ◽  
Auto Correlation Function ◽  
Non Gaussian ◽  
Gaussian Surface ◽  
Lubrication Conditions

Measurements of surface roughness on hydrostatic bearing slipper indicate that the surfaces are not always Gaussian. Previous studies in this area were primarily concerned with Gaussian surfaces. In this research the effects of non-Gaussian surface roughness on the performance of profiled hydrostatic thrust bearings are analyzed. This study is applicable to the lubrication conditions where the surface roughness is of the same order of magnitude as the minimum film thickness. Surfaces with different skewness, kurtosis, mean, auto-correlation function and standard deviation are generated numerically using a combination of Fast Fourier Transform (FFT) and Johnson translatory system. The finite difference method is used to solve the Reynolds lubrication equation. The effect of roughness on the load carrying capacity is investigated and compared with the results for ideal smooth surfaces.

Oil Film Angular Stiffness Determination in a Hydroelectric Tilting Pad Thrust Bearing

2010 ◽  
Author(s):  
D. V. Srikanth
Keyword(s):  
Reynolds Equation ◽  
Solution Procedure ◽  
Two Dimensions ◽  
Algebraic Equations ◽  
Axial Loads ◽  
Oil Film ◽  
Thrust Bearings ◽  
Linear Algebraic Equations ◽  
Tilting Pad ◽  
Rotating Shafts

Tilting pad thrust bearings are designed to transfer high axial loads from rotating shafts to the static support structure. In the present paper, formulation of Reynolds’ equation for the bearing is done in two dimensions (planar). A finite difference method is used to convert the terms of the Reynolds’ equation in to a set of simultaneous linear algebraic equations. A solution procedure for finding value of the pressure in the oil film is described. Numerical integration of the pressure values gives the load distribution. Subsequently, the study of angular stiffness of the film is done by varying the value of the oil film thickness and calculating torques at three different film shapes 1, 2 & 3 of the pad. The angular stiffness, differential displacement and load pertaining to the 3-2 pair are calculated for 0.5%–20% variation of ho. The results obtained show that the values of Kt* and K* converge asymptotically.

scholarly journals Numerical analysis and experimental research on load carrying capacity of water-lubricated tilting-pad thrust bearings

2018 ◽  
Vol 19 (2) ◽  
pp. 201 ◽  
Author(s):  
Xiuli Zhang ◽  
Gengyuan Gao ◽  
Zhongwei Yin ◽  
Yanzhen Wang ◽  
Chao Gao
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Optimization Method ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Lubrication Regime ◽  
Tilting Pad ◽  
Load Carrying ◽  
Minimum Film Thickness

Water-lubricated bearings are expected to be widely used because of convenience, green, safe and energy saving. The purpose of this study is to investigate the load carrying property of water-lubricated tilting-pad thrust bearings. A large amount of numerical analyses are undertaken based on computational fluid dynamics and the optimization method of pivot location and the calculation method of minimum film thickness are summarized. A thrust bearing is designed according to the numerical results and is tested by experiments. The experimental results validate the numerical method and the minimum film thickness to surface roughness ratio corresponding to the change of bearing lubrication regime from mixed lubrication to hydrodynamic lubrication is obtained.

scholarly journals Observer-Based Control of Tilting-Pad Thrust Bearings

Lubricants ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Edward H. Smith
Keyword(s):  
Maximum Temperature ◽  
Inlet Temperature ◽  
Output Measurement ◽  
Thrust Bearings ◽  
Estimated Parameters ◽  
Steady State Operation ◽  
Tilting Pad ◽  
Minimum Film Thickness ◽  
Rich Information ◽  
To Receive

The active control of hydrodynamic bearings is beginning to receive more attention in the pursuit of lower power losses and reduced maintenance. This paper presents a method by which, from simple measurements, rich information can be deduced from a running bearing that can used to modify the operating parameters of the unit. The bearing is a line-pivot, unidirectional, steadily loaded, directly lubricated tilting pad thrust bearing. This control is achieved by designing an Observer whose inputs include the output measurement(s) from the bearing. The Observer is, in some ways, an inverse model of the bearing (or Plant) that runs in parallel to the bearing and estimates the states of the bearing, such as the applied load, pivot height, minimum film thickness, maximum temperature, effective temperature and power loss. These estimated parameters can then be used in a control algorithm to modify bearing parameters such as inlet temperature or pivot location. It is demonstrated that disturbances in the load on the bearing can be detected simply by measuring a representative temperature in the bearing or changes in pivot height. Appropriate corrective action can then be employed. Whilst only steady-state operation is considered, the method could be developed to study time-varying situations.

Dynamic Analysis of Tilting-Pad Journal Bearing—Influence of Pad Deformations

1994 ◽  
Vol 116 (3) ◽  
pp. 621-627 ◽  
Author(s):  
H. Desbordes ◽  
M. Fillon ◽  
C. Chan Hew Wai ◽  
J. Frene
Keyword(s):  
Film Thickness ◽  
Pressure Field ◽  
Journal Bearing ◽  
Maximum Pressure ◽  
Tilting Pad ◽  
Minimum Film Thickness ◽  
Dimensional Finite Element ◽  
The One ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

A theoretical nonlinear analysis of tilting-pad journal bearings is presented for small and large unbalance loads under isothermal conditions. The radial displacements of internal pad surface due to pressure field are determined by a two-dimensional finite element method in order to define the actual film thickness. The influence of pad deformations on the journal orbit, on the minimum film thickness and on the maximum pressure is studied. The effects of pad displacements are to decrease the minimum film thickness and to increase the maximum pressure. The orbit amplitude is also increased by 20 percent for the large unbalance load compared to the one obtained for rigid pad.

Electrical pitting of tilting-pad thrust bearings: Modelling and experimental evidence

2016 ◽  
Vol 103 ◽  
pp. 475-486 ◽  
Author(s):  
Steven Chatterton ◽  
Paolo Pennacchi ◽  
Andrea Vania
Keyword(s):  
Experimental Evidence ◽  
Thrust Bearings ◽  
Tilting Pad

An Accurate Solution of the Gas Lubricated, Flat Sector Thrust Bearing

1977 ◽  
Vol 99 (1) ◽  
pp. 82-88 ◽  
Author(s):  
I. Etsion ◽  
D. P. Fleming
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Thickness Distribution ◽  
Maximum Load ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Thrust Bearings ◽  
Practical Design ◽  
Minimum Film Thickness

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

A Three-Dimensional Analysis of Thermohydrodynamic Performance of Sector-Shaped, Tilting-Pad Thrust Bearings

1983 ◽  
Vol 105 (3) ◽  
pp. 406-412 ◽  
Author(s):  
Kyung Woong Kim ◽  
Masato Tanaka ◽  
Yukio Hori
Keyword(s):  
Dimensional Analysis ◽  
Environmental Conditions ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Dimensional Variation ◽  
Lubricant Viscosity

The thermohydrodynamic performance of the bearing is analyzed, taking into account the three-dimensional variation of lubricant viscosity and density. The effect of pivot position and operating and environmental conditions on the performance is studied. The present analysis is compared with the isoviscous or the two-dimensional analysis, and is found to predict the bearing performance more accurately.

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