Thrust Bearing Research Articles

Effect of surface square textures on the physical field of static and dynamic pressure thrust bearings and multi-objective optimization

Purpose The lubrication performance of static and dynamic pressure thrust bearings is improved by introducing texture on the sealing edge. Design/methodology/approach Through model building, meshing and boundary condition setting, the influence of square texture on oil film lubrication performance was simulated and analyzed, and an improved algorithm was applied to perform optimization of lubrication performance. Findings The findings of this study reveal that the optimum lubrication performance is attained when adjusting the parameters of the square texture to 0.12 mm, 0.1 mm, 1 mm and 34 mm. In such circumstances, the thrust bearing with square textures demonstrates an increase in loading capacity of around 19% and a temperature reduction of about 2ºC compared to a smooth thrust bearing. Originality/value The original Reynolds equation is revised, and the influence of square texture on the physical field of oil film is analyzed, considering the turbulence state and cavitation phenomenon. The multi-objective function under square texture parameters was established using BP neural network, and the improved multi-objective salp swarm algorithm was used to optimize the process parameters.

Modeling of Textured Hydrostatic Thrust Bearings and Lubricating Films with Variable Thickness

Modeling of Textured Hydrostatic Thrust Bearings and Lubricating Films with Variable Thickness

A 3D design of the hydrodynamic pocketed thrust bearing with slip engineered for eliminating cavitation

Nowadays, researchers are interested in surface modification of bearings by adding texture to increase bearing performance. Regrettably, modifications in surface roughness can induce cavitation. Conversely, slip engineering can enhance pressure to effectively eliminate cavitation. The objective of this work is to present a 3D design for thrust bearing that integrates pockets and slip engineering techniques in order to improve the load carrying capacity of the bearing and reduce cavitation. The originality of this study on thrust bearing is in the integration of surface texture, slip engineering, and cavitation. A CFD modeling approach is employed to simulate the slip formation in the design. Implementing slip induces hydrophobicity on the surface by introducing velocity to the fluid at the contact with the bearing pad. The simulation involves two types of bearings: radial pocket and multitexture, each with various slip positions. The important study's findings indicate that the radial pocket design, which incorporates slip formations both between and inside the pocket, can enhance the load carrying capacity by as much as 259.2 % compared to the absence of slip formation. When using the multitexture type, the load bearing capability can rise by up to 179 %. In the multitexture configuration, pressure is uniformly distributed throughout the bearing surface. To enhance the comprehensiveness of the research, the findings of this study are also compared to those of earlier conducted studies on circumferential pocket and closed pocket types. Arranging slip correctly has been empirically shown to enhance the load carrying capability of bearings.

Experimental Performance Evaluation of a Lightweight Additively Manufactured Hydrodynamic Thrust Bearing

In this paper, a lightweight additively manufactured (AM) fixed geometry hydrodynamic thrust bearing fabricated via laser powder bed fusion (LPBF) is experimentally compared to a traditionally manufactured cast aluminum alloy thrust bearing of similar design. The purpose of this study is to evaluate how weight-saving design features in the AM bearing affect active critical hydrodynamic performance parameters to better understand in-service viability. Under various static operating conditions, performance parameters such as hydrodynamic pressure distribution, minimum oil film thickness (MOFT), bearing temperature and increase in oil temperature are measured. Compared to the traditionally manufactured bearing, the AM bearing showed an average increase in minimum oil film thickness of 53%, an average increase in trailing edge hydrodynamic pressure of 116%, while exhibiting an average decrease in bearing temperature of 1%. Experimental results are compared to numerical simulation showing reasonably good agreement.

Effect of Planetary Gear Set Designs on Thrust Bearing Power Loss in Automatic Transmission

Effect of Planetary Gear Set Designs on Thrust Bearing Power Loss in Automatic Transmission

Preliminary Studies on Gas Foil Thrust Bearings with Stepped Foils

Preliminary Studies on Gas Foil Thrust Bearings with Stepped Foils

A comparative study on turbulent models for three-dimensional thermo-hydrodynamic analysis of textured thrust bearing

A comparative study on turbulent models for three-dimensional thermo-hydrodynamic analysis of textured thrust bearing

Air Foil Thrust and Journal Bearing Coatings: A Review

Abstract Surfaces of air foil thrust and journal bearings in high-speed turbomachinery are coated to improve their operational integrity, particularly when the aerodynamic load-carrying capacity is reduced during instances of startup and shutdown. Surface coatings, as protective barriers in air foil bearings, can mitigate the adverse effects of direct surface interactions on such occasions. This article provides an in-depth review of the body of important research conducted for the study of coated air foil thrust and journal bearings, highlighting the state of the art in coating technology. The review features the role of composite coatings, designed to provide favorable thermal, mechanical, and frictional characteristics. This article also highlights the trends in the selection of coatings for air foil bearings, pertinent to desired thermo-mechanical performance.

Observation of wear around surface crack of PEEK thrust bearing under rolling contact fatigue in water

Abstract Rolling bearings are important mechanical elements for machines. Poly-ether-ether-ketone (PEEK) polymer is a suitable material for bearings in water and corrosive conditions because of its excellent water and chemical resistance. Some study had been examining rolling contact fatigue (RCF) tests in water; however, the competition between cracks propagation and wear on the surface of PEEK bearing in water was not clear. In the present study, in order to evaluate the crack propagation and wear process, RCF test with PEEK thrust bearings at 3750 [N] in water was carried out. The lengths of the surface cracks and the profiles of the grooves were observed at different number of cycles. In addition, so as to identify the cracks which cause the flaking, start-stop test was carried out. We found the surface crack, which was initially observed at 4.62×105 cycles, were gradually worn down and completely disappeared at 6.32×105 cycles. We concluded that rolling contact fatigue caused some surface cracks of PEEK to wear down in water condition.

Changes in Surface Topography and Light Load Hardness in Thrust Bearings as a Reason for Tribo-Electric Loads

The article focuses on the findings of endurance tests on thrust bearings. In addition to the mechanical load (axial load: 10 ≤ C0/P ≤ 19, lubrication gap: 0.33 µm ≤ h0 ≤ 1.23 µm), these bearings are also exposed to electrical loads (voltage: 20 Vpp ≤ U0 ≤ 60 Vpp, frequency 5 kHz and 20 kHz), such as those generated by modern frequency converters. In a previous study, the focus was on the chemical change in the lubricant and the resulting wear particles. In contrast, this article focuses on the changes occurring in the metallic contact partners. Therefore, the changes in the surface topography are analysed using Abbott–Firestone curves. These findings show that tests with an additional electrical load lead to a significant reduction in roughness peaks. A correlation to acceleration measurements is performed. Moreover, it is shown that the electrical load possibly has an effect on the light load hardness. An increase in the occurring wear could not be detected during the test series. Also, a comparison with mechanical reference tests is made. The article finally provides an overview of different measurement values and their sensitivity to additional electrical loads in roller bearings.

Multiscale Mixed Elastohydrodynamics in Inclined Fixed Pad Thrust Bearing Involving Surface Roughness and Low Clearance

The film pressures, surface separation profiles and carried loads of the hydrodynamic inclined fixed pad thrust bearing with the sandwich films were calculated by the multiscale approach when the bearing clearance was low and the combined effects of the adsorbed layer, the surface roughness and the surface elastic deformation were incorporated; The sandwich film consists of two physically adsorbed layers respectively on the coupled bearing surfaces and the intermediate continuum fluid film. The results show that the surface roughness intrinsically generates the film pressure ripples, but the rough surface is somewhat flattened and the film pressure ripples are a bit reduced by the surface elastic deformation. For a given sliding speed and a given original bearing clearance, the surface elastic deformation results in the significant reductions of both the maximum film pressure and the carried load of the bearing especially for a strong fluid-bearing surface interaction. In spite of this, the slope of the increase of the bearing load with the magnitude () of the surface roughness is nearly the same for the elastic surfaces with that for the rigid surfaces. The presence of the surface roughness does not qualitatively alter the influence of the surface elastic deformation on the performance of the bearing.

Active Diagnostic Experimentation on Wind Turbine Blades with Vibration Measurements and Analysis

Abstract This paper deals with the key operational problems of wind turbosets, especially offshore, where vibrations are generated by rotor blades, as a consequence of erosive wear or icing. The primary causes of the imbalance of wind turbine rotors have been characterised, the observable symptoms of which include various forms of vibrations, transmitted from the turbine wheel to the bearing nodes of the power train components. Their identification was the result of an active diagnostic experiment, which actually entered the aerodynamic-mass imbalance of a turbine rotor into a wind power train, built as a small scale model. The recording of the observed monitoring parameters (vibration, aerodynamic, mechanical and electrical) made it possible to determine a set of symptoms (syndrome) of the deteriorated (entered) dynamic state of the entire wind turboset. This provides the basis for positive verification of the assumed concept and methodology of diagnostic testing, the constructed laboratory station and the measuring equipment used. For this reason, testing continued, taking into account the known and recognisable faults that most often occur during the operation of offshore wind turbosets. Transferring the results of this type of model research to full-size, real objects makes it possible to detect secondary (fatigue) damage to the elements transmitting torque from the wind turbine rotor to the generator early, especially the thrust bearings or gear wheel teeth.

Research on the Lubrication Performance of Hydrostatic Thrust Bearings Considering Dynamic Pressure Effect and Oil Film Pressure Loss

A lubrication performance mathematical model considering the dynamic pressure effect and pressure loss is proposed for stepped hydrostatic thrust bearings. The influence mechanism of rotational speed and load on the static pressure, dynamic pressure, pressure loss, total pressure, and total temperature of the clearance oil film is systematically discussed through a combination of theory, simulation, and experiment. The investigation found that the total temperature of the oil film decreases with increasing load and increases with increasing rotational speed. The pressure loss also becomes increasingly significant with higher rotational speeds. The dynamic pressure is not limited by the load but increases with the increase in rotation speed. The oil film pressure loss is jointly borne by static pressure and dynamic pressure within the range of 0 to 160 rpm and mainly borne by static pressure within the range of 160 to 200 rpm. Additionally, the trends of static pressure, dynamic pressure, total pressure, and temperature in the experiment are nearly consistent with those predicted by numerical simulations, thereby validating the effectiveness of the research methodology employed in this article.

Numerical and experimental research on the hydro-electromagnetic levitation micropump

Micropump is the core component of the microfluidic systems. However, most mechanical micropumps are using the traditional contact bearings that are troubled by wear-out failure. Hydraulic levitation, which can make the rotating components levitate without any solid-solid contact, provides efficient solution to this long-standing challenge. Nevertheless, the current hydraulic levitation technology must utilize micron microgroove structure to produce thrust forces, therefore enlarging the assemble difficulty and manufacture cost. Alternatively, a novel kind of hydro-electromagnetic levitation micropump (HELP) without grooved thrust bearing is designed in this study. Taking advantage of the coupling behavior between the electromagnetic force and hydraulic force, the rotor of the HELP can levitate in the working fluid in all directions. Thereafter, the mechanisms of levitation forces formation are elucidated by the simulations of fluid flow and motor. Results indicate that the levitation bearing can provide sufficient load capacity in all working conditions, especially in high speeds. Based on the hydro-electromagnetic levitation principle, the HELP prototype is manufactured, whose overall size is as large as a coin, but can output the hydraulic performance of over 3160 mL/min and 90.5 kPa at 20000 RPM, which is several times over other micropumps. To verify the rotor levitation performance, the levitation trajectory test benches are built on the basis of laser displacement sensors. Results prove that the designed HELP can levitate stably in all directions at all rotational speeds. The proposed levitation micropump may be an excellent choice for powering the liquid cooling systems with high performance and high reliability.

Optimum texture shape under different lubrication conditions applied to the start-up phase of journal bearings

This paper presents a parameterized model to optimize the texture units using an improved particle swarm optimization. The texture units are optimized under three lubrication states: boundary lubrication, mixed lubrication, and hydrodynamic lubrication, by utilizing the Stribeck curve. The optimal texture units can be applied to journal bearings and thrust bearings in different operating conditions to achieve maximum load-carrying capacity. The paper applies the optimal textures under the three lubrication states to the start-up stage of journal bearings to examine the lubrication performance and dynamic characteristics of the textured journal bearing system. The results demonstrate that compared to the untextured journal-bearing system, the introduction of optimal textures improves the tribological performance of the journal-bearing system, and the optimal textured units under hydrodynamic lubrication have the best friction reduction effect. Furthermore, it is found that the introduction of textures has no significant effect on the dynamic characteristics of the journal bearings.

Analytical study on hybrid thrust foil bearing, structural characterization and measurement of static performance

This work presents a novel hybrid foil thrust bearing (HFTB) with an outer diameter of 154 mm, along with simulation and test results. The HFTB incorporates a high-pressure air/gas injection to the taper portion of the thrust foil bearing, boosting the hydrodynamic effect on the main bearing surface and hydrostatic load capacity at zero speed. The bearing has high load capacity, low power loss, and no friction/wear during startup and shutdown. Firstly, push-pull tests were conducted on a double-acting HFTB configuration to evaluate the nonlinear structural stiffness of the bump foil structure. The measured nonlinear stiffness model was adopted to predict the overall bearing performance under various speeds and loads. The simulation uses an advanced model which predicts the 2D plate top foil deflection with physical bump locations mapped from the actual hardware. The simulation confirms that the hybrid operation significantly increases the load capacity compared to hydrodynamic bearing due to the boost effect of hydrostatic pressure in the main film. Tests were conducted at 10krpm, 15krpm, and 20krpm to measure load capacity, power loss, and average film thickness. At 20krpm, a maximum axial load of 1711 N was achieved before bearing failure. Ultimately, the novel HFTB shows excellent static performance with potential for use in Organic Rankine Cycle (ORC) generators and other large oil-free turbomachines.

Study on vibration mechanism and dynamic characteristics for TBM main bearing defects

As the key component of TBM main driving system, the main bearing plays an indispensable role both in its service life and the normal operation of the TBM. While prior investigations predominantly focused on static analyses of the main bearing, only a scant few delved into its dynamic characteristics and the vibration mechanism. In order to explore the dynamic characteristics of TBM main bearing, a comprehensive dynamics model of the TBM main bearing considering local defects is established, the vibration mechanism of the main bearing with local defects is revealed, and the influence of uneven load is investigated. Furthermore, the effects of roller wear and bearing clearance on the vibration response of the main bearing are analyzed, which systematically describes the real motion of the main bearing. Finally, a main bearing scaling test rig is constructed, and the proposed model is validated through experiments and simulations, demonstrating its good accuracy. In addition, the results show that the incremental imposition of uneven load correlated with a rising trend in the root mean square (RMS) value of vibration response. Moreover, maintaining an optimal axial clearance is pivotal in ensuring the reliable operation of the main bearing. The research work in this paper provides theoretical scaffolding for the defect diagnosis of TBM main bearing, whilst also serves as an analytical cornerstone for future explorations into the dynamics of various types of thrust bearings.

Effects of differently shaped textures on the tribological properties of static and dynamic pressure thrust bearings and multiobjective optimization

PurposeThe purpose of this study is to evaluate three types of textures designed to enhance the tribological performance of static and dynamic pressure thrust bearings.Design/methodology/approachTo explore the effects of different types of textures on tribological performance, the Reynolds equation is modified using lubrication theory and computational fluid dynamics methods while considering the influence of cavitation and turbulence on the physical field. In addition, the tribological performance is optimized through an improved selection algorithm based on Pareto envelope (PESA).FindingsThe results indicate that textured thrust bearings exhibit superior tribological performance compared to untextured ones. The circular texture outperforms other textures in terms of load-bearing and friction performance, with improvements of approximately 28.8% and 18.9%, respectively. In addition, the triangular texture exhibits the most significant temperature improvement, with a reduction of approximately 1.93%.Originality/valueThe study proposes three types of textures and evaluates the friction performance of thrust bearings by modifying the Reynolds equation. In addition, the optimal texture design is determined using an improved selection algorithm based on PESA.

The errors of the shaft's axial movement measuring in the single-coil-eddy-current-sensors-based system for the monitoring the state of radial thrust bearing of the NK-33 liquid rocket engine’s turbopump unit

The errors of the shaft's axial movement measuring in the single-coil-eddy-current-sensors-based system for the monitoring the state of radial thrust bearing of the NK-33 liquid rocket engine’s turbopump unit

Tribological behavior of textured polycrystalline diamond compact for thrust bearings using the surface morphology of dung beetles as an inspiration

To improve the lubrication and friction characteristics of diamond thrust bearings and extend their service life, this study took inspiration from the anti-adhesion and wear-resistant properties of a dung beetle body surfaces and used laser processing to create dimples on the surface of a polycrystalline diamond compact (PDC). The spacing, diameter, and depth of the dimples were designed and optimized using an orthogonal experimental method. The wear mechanism of the textured PDC was analyzed using various microscopic characterization methods. The results showed that the bio-inspired dimple-textured PDC exhibited better tribological behavior and was an effective way to enhance the lifetime and reliability of diamond thrust bearings.