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.

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.

scholarly journals Cooled Pads for Tilting-Pad Journal Bearings

Lubricants ◽  
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.

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.

Increase of Operational Safety of Tilting-Pad Journal Bearings by Extraction of Hot Oil at the Trailing Edge

2015 ◽  
Author(s):  
Sebastian Kukla ◽  
Nico Buchhorn ◽  
Beate Bender
Keyword(s):  
Film Thickness ◽  
Carrying Capacity ◽  
Maximum Temperature ◽  
Load Carrying Capacity ◽  
Trailing Edge ◽  
Tilting Pad ◽  
Load Carrying ◽  
Operational Safety ◽  
Minimum Film Thickness ◽  
Safety Parameters

A theoretical study is presented with the main objective on the operational safety parameters (minimum film thickness and maximum pad temperature) and thermomechanical deformations of a ø500 mm rocker pad tilting-pad journal bearing (TPJB) for application in large turbo machinery. It can be described by the following specifications: Five pads, 0.23 nominal preload, 60% offset, 56° pad arc angle, 350 mm pad length and 1.28‰ relative bearing clearance. Theoretical investigations are carried out for circumferential speeds up to 78 m/s and static loads up to 3.60 MPa. The simulation tool simultaneously solves both Reynolds and energy equations for the oil film (3D temperature distribution) on the one hand and computes thermomechanical deformations of the pad on the other hand. The simulations are conducted for a single pad and are supported by boundary conditions taken from experiments. The results with regard to static bearing characteristics and pad deformation show good agreement with experiments. The impact of axial pad arching on operational safety parameters and load-carrying capacity are shown and compared to experimental results. It is shown that the axial deviation in film thickness Δh can be even higher than the minimum film thickness hmin. This leads to reduced hydrodynamic pressure build-up towards the axial edges and therefore significantly decreased safety parameters or load-carrying capacity. In order to reduce pad crowning, radial bores through the pad body are modelled to simulate the extraction of hot oil from the trailing edge. In the simulation, the hot oil is used to heat up the back of the pad for a decrease of radial temperature gradients and thus pad arching. It is shown that by extracting 0.4 l/s of hot oil, a decrease in axial pad crowning from Δh = 47μm to Δh = 26μm can be achieved and that this leads to a decrease of 7.8 K in maximum temperature and an increase of 5 μm in minimum film thickness respectively a gain of load-carrying capacity of 0.4–0.6 MPa.

THD Analysis of Tilting Pad Thrust Bearings—Comparison Between Theory and Experiments

1999 ◽  
Vol 122 (2) ◽  
pp. 412-417 ◽  
Author(s):  
T. Almqvist ◽  
S. B. Glavatskikh ◽  
R. Larsson
Keyword(s):  
Three Dimensional ◽  
Experimental Investigations ◽  
Inlet Temperature ◽  
Transfer Coefficients ◽  
Thrust Bearings ◽  
Heat Transfer Coefficients ◽  
Pressure Profiles ◽  
Tilting Pad ◽  
Temperature And Pressure ◽  
Theory And Experiments

The objective of the present research is to verify a THD model of hydrodynamic thrust bearings. The developed model of a pivoted pad bearing, which can tilt both radially and circumferentially, allows for three-dimensional temperature distribution in the oil film and in the pad, as well as two-dimensional temperature variation in the runner. Viscosity and density are treated as functions of both temperature and pressure. Experiments have been performed on a test rig, containing two identical equalizing pivoted pad thrust bearings. Power loss, runner temperature, and pressure profiles as a function of load and rotational speed are compared for both theoretical and experimental investigations. Fairly good agreement has been found when the oil inlet temperature and heat transfer coefficients have been estimated in order to get the same runner temperature in both theory and experiment. [S0742-4787(00)00802-X]

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.

Increased Load Carrying Capacity of Large Tilting-Pad Journal Bearings by Injection of Cold Oil

2016 ◽  
Author(s):  
Nico Buchhorn ◽  
Sebastian Kukla ◽  
Beate Bender
Keyword(s):  
Film Thickness ◽  
Carrying Capacity ◽  
Load Capacity ◽  
Maximum Temperature ◽  
Load Carrying Capacity ◽  
Tilting Pad ◽  
Load Carrying ◽  
Minimum Film Thickness ◽  
Safety Parameters ◽  
The Impact

In this paper a theoretical study with the aim to achieve higher load capacity of large tilting-pad turbine bearings is presented. The main focus is set on the reduction of thermal gradients inside the pad and thus, of adverse thermomechanical deformations. This allows for the increase of either the load carrying capacity, minimum film thickness hmin, and/or decrease maximum pad temperature Tmax. Subject of the investigation is a 5-pad tilting-pad bearing with rocker pivots. Each pad arc measures 56° and the pivot is positioned at 60 %. By having a 500mm inner diameter the 350mm long bearing features a relative clearance of 1.28% and nominal preload of 0.23. It is shown that the axial pad bending Δh (crowning) has a major impact on film thickness and pressure distributions and thus on the operational safety parameters. In order to reduce this effect, radial bores through the pad supplying pressurized cold oil (Tinj = 50 °C) are simulated. Despite the evident increase in oil film pressure, the primary purpose of the injection is to rinse away the layer of hot oil sticking to the pad surface. The maximum pad temperature and the overall pad temperature gradients are thereby decreased. The code used for simulation solves Reynolds and energy equations and computes thermomechanical deformations simultaneously. However, the simulations are carried out for one single pad only and are therefore supported by boundary conditions taken from experiments. In order to determine the impact of the approach on the static bearing characteristics, diameter and location of the bores are varied (0.3mm ≤ db ≤ 0.5mm). It is shown that pad crowing can be reduced significantly: The axial deviation of the film thickness Δh can be decreased from Δh = 47 μm to Δh = 31 μm, while the maximum temperature Tmax can be decreased by 20 K. Further, the minimum film thickness hmin can be increased by 16 μm. Subsequently, allowing the same limits for hmin and Tmax for the new design, the load capacity can be raised by up to 1.21MPa ≙ 44 %.

Measurements of Maximum Temperature in Tilting-Pad Thrust Bearings

1988 ◽  
Vol 31 (1) ◽  
pp. 44-53 ◽  
Author(s):  
D. Horner ◽  
J. E. L. Simmons ◽  
S. D. Advani
Keyword(s):  
Maximum Temperature ◽  
Thrust Bearings ◽  
Tilting Pad

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.

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