Thrust Bearing Research Articles

Analysis of Rotation Magnetized Direction Permanent Magnet Thrust Bearing for Maximum Characteristics Using a Complete Generalized Optimization Procedure and a Computational Framework

Analysis of Rotation Magnetized Direction Permanent Magnet Thrust Bearing for Maximum Characteristics Using a Complete Generalized Optimization Procedure and a Computational Framework

Micro-Clearance Oil Film Temperature Field Characteristics of High Speed and Heavy Type Hydrostatic Thrust Bearing under Extreme Operating Conditions

Micro-Clearance Oil Film Temperature Field Characteristics of High Speed and Heavy Type Hydrostatic Thrust Bearing under Extreme Operating Conditions

Effect of Cross-Sectional Profile of Circular Dimples on Hydrodynamic Lubrication Characteristics of Thrust Bearings

The effects of three types of dimples with different internal structures on the fluid lubrication characteristics of thrust bearings were investigated. The load-carrying capacity and the frictional torque were measured. The measurements were performed with a fixed constant film thickness. The behaviours of cavitation bubbles occurred within the dimple were observed through the rotating glass plate. Three types of internal structures of dimples were tested: cylindrical, sphere and conical. The measurement results were simulated by the Reynolds equation. As the results, the load-carrying capacity increased as the rotational speed increased. The cylindrical internal structure built up the largest pressure at the trailing edge, and consequently the largest load-carrying capacity. The frictional torque also increased with increasing the rotational speed. However, the effect of the internal structure on the frictional torque was not significant.

Load-carrying characteristics of bump-type gas foil thrust bearings

The load capacity improvement of gas foil thrust bearings (GFTBs) is crucial in high-speed turbomachinery, which relies on the advanced design of foil structures and urgently requires a deep understanding based on comprehensive models. This paper presents an exhaustive model of GFTB combining isoparametric elements with contact mechanics, which enables the analysis of arbitrarily shaped foils. The proposed model considers bump interactions and frictional forces as well as the exact geometry of foils and bump height errors. Its accuracy is verified by comparison with commercial software simulations, experimental data and literature results. The impact of the bump foil arrangement along the radial and circumferential directions has been thoroughly analyzed based on the developed model. This work also fills a gap in the literature by obtaining the effects of bump height errors on bearing load-carrying performance. A drastic reduction of load capacity is observed when considering the bump height errors, and the reasons are explained in detail through analyzing the aero-elastic characteristics of fluid field. The results in this study can be instructive for bearing designers.

Improvement of methods for controlling power oil of cooling tower recycling water supply units at Rivne nuclear power plant

The relevance of the study is conditioned upon the fact that at nuclear power plants, water pumping units using energy oils are operated in the heat exchange equipment of power units. The diagnostic criteria of oils allow identifying defects in the operation of technological equipment. The purpose of the work – to increase the reliability of the operation of oil-filled power equipment by improving the monitoring of the physical and chemical properties of power oil TP-30. The main attention is devoted to increasing the reliability of the operation of oil-filled power equipment by improving the monitoring of the physical and chemical properties of TP-30 power oil. Experimental studies were conducted by chromatography, and gas and liquid extraction using appropriate laboratory equipment. When exploring the content of chemical elements in the segments of the thrust bearing of the cooling tower pumping unit, which is based on Sn, an increase in the content of copper Cu and Sb was observed, which exceeded the standard by an average of 1.2 and 1.1 times, respectively. Most of the analysed physical indicators of oil quality (water content, kinematic viscosity, flash point, acid number) did not demonstrate deviations from the standard values. Only an increase in the mass fraction of mechanical impurities by 0.0026% relative to the standard was noted during the incoming inspection of TP-30 oil. The results of the operational control of the oil in terms of a set of physical indicators fully complied with the established technological standards. The highest content of soluble gases in the oil (0.56% by volume) was recorded for propylene (C3 H6 ). It is recommended to use the relative content of soluble gases in Tp-30 oil to C3 H6 when identifying degradation processes. The absence of residuals of circulating power oil TP-30 in the surface waters of the Styr River during the operational event was established. Generalisations have been generalised about the necessity of expanding the diagnostic criteria for the quality of TP-30 oil, in particular, expanding the list of its physical indicators. In practical terms, the results obtained can be useful for monitoring the quality of other brands of petroleum oils in the systems of turbine units of nuclear power plants, which is important in terms of the safe operation of heat exchange equipment

Analysis of Air Foil Thrust Bearings with annular top foil including wear prediction, Part I: Modeling and simulation

This article features an Air Foil Thrust Bearing (AFTB) simulation model including wear prediction for a foil thrust bearing with an annular top foil. The bearing consists of 6 bearing sectors with independent bump foils, but possesses a single annular top foil with an embossed height profile. The bearing is analyzed by a detailed single-sector model utilizing symmetry properties and a cyclic coupling of the components. The compressible Reynolds equation and the 3D energy equation are used to obtain fluid film pressure and temperature. The model further includes thermoelastic deformations of the runner disk, elastomechanic deformations of the top and bump foils, and a detailed thermodynamic model of the rotor. A direct comparison of simulated and experimental results shows that top foil wear has to be taken into account in order to match simulated to measured data. Therefore, a wear algorithm is derived and incorporated into the thermo-elasto-hydrodynamic simulation model. Furthermore, the manufactured real top foil topology is determined by measurements in order to obtain in-depth topology information which is also included in the computation model. Simulation results with the TEHD model including a detailed surface analysis alongside a wear prediction are confirmed by measurements carried out on a dedicated test rig.

Evaluation of thermal stability of ultra-precision water-lubricated spindle

Minimizing spindle thermal deformation is of key importance for reaching high machining accuracy. In this study, the thermal stability of a spindle with water-lubricated hydrostatic bearings was investigated via simulation with experimental data for defining boundary conditions for the simulations. The simulation study was divided into two separate tasks. In the first stage, the temperature distribution in the water flowing through spindle bearings was determined using commercial FEM flow simulation software. The experimentally obtained temperatures of lubricant and spindle surfaces were used as boundary conditions for a finite volume problem that introduced the temperature distribution of the spindle body and water flowing around the spindle. Then, a thermal analysis of the spindle was performed using the temperature field obtained in the first stage to investigate thermal deformation of the spindle. Temperatures at specific parts of the spindle derived from the temperature distribution were used as boundary conditions for analysis in the second stage. The results were used to investigate the influence of spindle thermal deformation on the positioning accuracy of the end surface of the spindle rotor. The pattern of gap variations in journal and thrust bearings due to the thermal deformation of bearing surfaces was established. The thermal stability of a spindle under the influence of an external temperature field was evaluated using the bearing load capacity and stiffness as indicators. The bearing load capacity and stiffness were defined based on the pressure distribution on the bearing surfaces with consideration of the non-uniformity of the bearing gap due to thermal deformation. A separate study was conducted to investigate the effect of changing viscosity of increasing the temperature of lubricating fluid on bearing performance. Furthermore, the resulting displacement of the spindle rotor end, which directly affects machining error, is also discussed.

Tribological Properties of Carbon Fiber-Reinforced PEEK against 304 Stainless Steel with Reticulate Surface Texture.

With the aim of improving the durability and reliability of polyetheretherketone (PEEK) composites reinforced with carbon fiber (CF) as thrust bearings without lubricants, a reticulate surface texture was fabricated by plane honing on a stainless steel (SS) counterpart to promote its tribological properties. Pin-on-disk experiments were designed, with the results showing that the reticulate surface texture effectively reduces the friction coefficient from 0.40 to 0.20 compared with the polished SS surface, within the range of the pv value from 0.185 to 1.85 MPa∙m/s. The wear mechanism of the polished SS surface against CF-PEEK, proven with SEM and EDS observations as well as AE measurements, is revealed, falling into abrasive wear with SS particles embedded in the friction interface around the CF strips, causing three-body contact. The reduction in the friction coefficient of the textured SS disk against the CF-PEEK pin can be achieved due to diminution of the CF wear debris and SS particles, which are scraped off by the groove edges and trapped by the groove valleys, reducing the three-body abrasive wear, while the honed plateau is used as a flank surface like a cutting tool to scratch more soft PEEK particles as the transferred film, owing to adhesive wear. This investigation suggests that the SS disk with a honed surface structure can be used as the counterpart of CF-PEEK bearings with a low friction coefficient and wear rate under dry friction.

An explicit cavitation multigrid algorithm for accelerating simulation of surface-textured bearings

The cavitation has a potential effect on the performance of surface-textured bearings. The traditional mass-conserving cavitation algorithms based on the Gauss-Seidel iteration method become slow as the grid increases. The computation time is unacceptable once the grid consists of a large array of textures. This study developed an explicit cavitation multigrid algorithm to accelerate the simulation of surface-textured bearings. The algorithm was based on the Ausas cavitation algorithm with the advantage of a matrix-free implementation. Novel numerical technologies were developed to overcome the difficulty of the floating free boundaries caused by the cavitation characteristics. An example of surface-dimpled thrust bearings was studied to analyze the algorithm efficiency. The algorithm is shown to be approximate optimal under reasonable solution parameters. It is an alternative to other cavitation algorithms.

Research Developments of Aerostatic Thrust Bearings: A Review

In aerostatic thrust bearings (ATBs), a high-pressure gas film with a certain bearing capacity and stiffness is formed by passing high-pressure gas between the moving surface and the static surface. Aerostatic bearings have outstanding advantages in the following aspects: high precision, high speed, and long service life, etc. They are widely used in many fields, such as high-speed air spindles, precision machine tools, air-bearing guideways, turbine machinery, and high-speed drills. With the pursuit of higher efficiency and high-precision machining machinery, there is an increasing demand for high-performance ATBs. Much effort has been spent on the study of ATBs, such as improvements in load capacity and stiffness, and the enhancement of stability. Some significant progress has been achieved. In this paper, the research developments of ATBs are summarized from several aspects, such as theoretical models and experimental methods, static performance, dynamic performance, and applications. In addition, insights on the breakthrough and development trends of ATBs are put forward. It is hoped that this paper can provide some guidance for the design and application of ATBs.

Lubrication structure design of water lubricated rubber thrust bearing with spiral groove for shaftless rim driven thruster

The existing design methodologies generally rely on experience and the design-test-modify process to fulfill the urgent requirements of shaftless rim-driven thrusters for low and medium speed, high load capacity, and wear-resistant water-lubricated bearings. In order to innovate current design methods and improve the design capabilities of such bearings, this paper conducts research on the lubrication structure design of water-lubricated spiral groove rubber thrust bearings (SGRTBs). Furthermore, the model developed in this paper takes the effect of surface roughness into account, proposes a mixed lubrication analysis technique for water-lubricated SGRTBs, achieves the optimization design of the spiral groove structure parameters (spiral angle, groove width ratio, number of spiral grooves, and tilt angle), and addresses the mixed lubrication issue of typical spiral surface contact.

Micro-grooved hybrid spherical thrust bearing with Non-Newtonian lubricant behaviour

Recent tribology research has primarily focused on leveraging engineered grooved surfaces to enhance the lubrication performance of tribo-contacts. The performance of fluid film bearings may be improved by using a properly designed micro-groove on the surface of bearing. This paper deals with the performance of micro-grooved hole-entry hybrid spherical thrust bearing (HSTB) considering Non-Newtonian behavior of the lubricant. To analyse the Non-Newtonian behaviour of lubricant the cubic law model has been used. The solution of the governing Reynold equation in the fluid film domain of the hole-entry hybrid spherical thrust bearing is obtained by the FEM. In this study, the influence of rectangular and circular shaped micro-groves has been analysed. The parametric analysis has also been performed to obtain the optimum attributes (i.e. w¯g,d¯g,l¯gr) of the micro-grooves for both the shapes. The present investigation shows that the performance of the hole-entry hybrid spherical thrust bearing gets enhanced by considering the micro-grooves on the surface of bearing. Furthermore, the bearings performance is affected by the geometry of the micro-groove used. The value of fluid film reaction (F¯y) and stiffness coefficient (S¯) is observed to be increased by 23.33% and 343.98% at εy = 0 and κ¯=1 for the case of rectangular-shaped micro-grooved hole-entry HSTB configuration.

A Review on Performance Characteristics of an Air Foil Thrust Bearing

The axial loads of high-speed rotating turbo machines are supported by self-acting hydrodynamic components known as air foil thrust bearings (AFTB). The load bearing capability of these bearings depends primarily on the foil structure and secondarily on the operating conditions. The present review enlightens on the tribological performance parameters of the said bearing in enhancing the load carrying capacity. Various design and fabrication methods including theoretical models are briefly summarised and comparisons of experimental results are presented in order to reveal the possible research gap that leads in optimising the gas lubricated foil thrust bearings (GFTB) for their better employment in typical applications.

Cutting Force When Machining Hardened Steel and the Surface Roughness Achieved

This article deals primarily with the problem of determining the cutting force when machining hardened steels. For this study, the steel used was 100 Cr6, number 1.3505. The secondary aspects of the study focused on the evaluation of the surface quality of machined samples and the recommendation of cutting conditions. A wide variety of components are used in engineering, the final heat treatment of which is hardening. These components are usually critical in a particular product. The quality of these components determines the correct functioning of the entire body of technical equipment, and ultimately, its service life. In our study, these are the core parts of thrust bearings, specifically the rolling elements. The subject of this experiment involves machining these components in the hardened state with cubic boron nitride tools and the continuous measurement of the cutting force using a dynamometer. The machining is carried out on a conventional lathe. A total of 12 combinations of cutting conditions were set. Specifically, for three cutting speeds of 130, 155 and 180 m·min−1, the feed rates of 0.05 and 0.1 mm·rev−1 and the cutting widths of 0.2 and 0.35 mm, were evaluated The evaluation assessed the surface quality by both touch and non-touch methods. A structural equation with the appropriate constants and exponents was then constructed from the data obtained using the dynamometer. The experiment confirmed the potential of achieving a value of the average arithmetic profile deviation Ra in the range of 0.3–0.4 when turning hardened steels with cubic boron nitride.

QQLMPA: A quasi-opposition learning and Q-learning based marine predators algorithm

Many engineering and scientific problems in the real-world boil down to optimization problems, which are difficult to solve by using traditional methods. Meta-heuristics are appealing algorithms for solving optimization problems while keeping computational costs reasonable. The marine predators algorithm (MPA) is a modern optimization meta-heuristic, inspired by widespread Lévy and Brownian foraging strategies in ocean predators as well as optimal encounter rate strategies in biological interactions between predator and prey. However, MPA is not without its shortcomings. In this paper, a quasi-opposition based learning and Q-learning based marine predators algorithm (QQLMPA) is proposed. This offers multiple improvements over standard MPA. Primely, Q-learning allows MPA to fully use the information generated by previous iterations. And also, quasi-opposition based learning serves to increase population diversity, reducing the risk of convergence to inferior local optima. Numerical experiments demonstrate better performance by QQLMPA on 32 benchmark optimization functions and three engineering problems: designs of pressure vessel, hydro-static thrust bearing, and speed reducer.

The Fluid-Structure-Thermal Performance Analysis of Gas Foil Thrust Bearing by Using Computational Fluid Dynamics

This paper presents a detailed three-dimensional (3D) thermo-elastic-hydrodynamic (TEHD) multi-physics model of the bump-type gas foil thrust bearing based on computational fluid dynamics (CFD). In this model, the moving mesh technology is applied in the fluid flow domain, and the new boundary condition of fully developed flow is applied at the inlet and outlet boundaries, which is consistent with the continuous property of fluid flow and has better convergence performance in CFD. The groove between pads is set as the symmetry boundary. The contact pairs with Coulomb friction and contact/separation behaviors are considered in the structure deformation and heat transfer. The simulation results indicated that the boundary pressure has a significant influence on the foil deformation. It also revealed the heat flux transfer path and temperature distribution in the gas foil thrust-bearing (GFTB) system.

Determination of steam leaks through faulty labyrinth seals of a steam turbine

BACKGROUND: When calculating the axial force acting on the thrust bearing of a steam turbine, when calculating the dimensions of the unloading piston, when calculating the efficiency of the turbine stages, it is necessary to determine the amount of steam leakage through its diaphragm and end seals. Existing methods make it possible to calculate leaks only through serviceable, undamaged labyrinth seals of several standard designs. However, during the operation of steam turbines, due to off-design axial and radial displacements of the rotor, labyrinth seals are often damaged - deformed, crushed or broken.
 AIMS: The purpose of the study is to develop a method for calculating leaks using direct CFD modeling in serviceable and damaged seals with typical failures, verify the simulation results by comparison with known methods and experimental data, and determine critical steam leaks through faulty labyrinth turbine seals.
 MATERIALS AND METHODS: A method for calculating the steam flow rate through serviceable and faulty labyrinth seals of a steam turbine using the capabilities of modern CFD methods is proposed and verified. The computational domain of modeling the front-end seal of the turbine, the features of setting the boundary conditions, the adaptive computational grid, and the numerical mathematical model used are described.
 RESULTS: The results of a numerical study of steam leakage through serviceable and damaged labyrinth end seals of the turbine are presented: with bent ridges in the seals, with partial or complete absence of ridges. The operation of the front-end seal of the turbine was simulated with several typical failures. It is shown that partial damage to the ridges of the front-end seal of the turbine, which is often encountered during operation, leads to a significant increase in steam leakage. It has been established that with significant damage to the ridges, an increase in steam leakage can lead to the exhaustion of the capacity of the steam pressure regulator in the seal, which leads to a malfunction of the turbine thrust bearing unloading system.
 CONCLUSIONS: The proposed technique and the results obtained can be used to calculate steam leakage through serviceable and faulty diaphragm and end labyrinth seals of turbines, when calculating the value of the axial force acting on the turbine thrust bearing in variable operating modes, the technique is useful in assessing the efficiency of the thrust bearing unloading system.

Numerical study on static performance of hydrodynamic bearing in high-speed liquid hydrogen centrifugal pump

High speed liquid hydrogen centrifugal pump is regarded as one of the most potential transmitting equipment in hydrogen distribution. Due to the cryogenic physical properties of liquid hydrogen, lubrication in the high-speed pump remains a challenge for its further application. In this paper, a novel grooved bearing using liquid hydrogen as lubricant has been proposed for long term reliable operation. Static performances of the bearing, including pressure distribution, vapor volume fraction and load capacity, have been evaluated numerically focusing on the cavitation effect. Considering the coupled effects in the bearing, orthogonal design method is used to optimize the structural parameters. With the optimal parameters, the load capacities of both journal and thrust bearing can be improved by 30% and 50%, respectively. In addition, the optimized coupled bearing can suppress the cavitation effectively, which is expected to be used in high-speed centrifugal pump with long-term and stable operation.

Investigations on the Load Capacity of Multilayer Foil Thrust Bearing Based on an Updated Complete Model

Abstract The multilayer gas foil thrust bearing (MLFTB) has four layers of foil structures with each having unique configuration and function. In this article, an updated complete model of the overlapped foil layers of MLFTB is established to calculate more accurate foil deformations and bearing performance by considering sufficient possibilities of separations between adjacent foil layers. The accuracy of the model is validated through the load capacity tests of MLFTB, which is presented for the first time in open publications. Based on the complete model, influences of individual and combined key foil structural factors on bearing load-carrying performance and top foil deformations are studied, revealing the function mechanism of each foil layer and obtaining the method of adjusting two-dimensional stiffness distributions. Furthermore, parametric optimizations toward improving the load capacity of this type of foil thrust bearing are conducted based on a developed algorithm. This study provides sufficient theoretical knowledge and designing methods for further investigations of MLFTB.

Modeling and simulation of the multiscale hydrodynamic wedge-platform thrust bearing

Modeling and simulation of the multiscale hydrodynamic wedge-platform thrust bearing