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This paper seeks to present some new designs of sliding bearings lubricated with magnetic fluids (ferrofluids) and the possibility of using them in modern bearing technology, in new computer and audiovisual equipment among others.

The paper presents new designs of journal, thrust and journal‐thrust sliding bearings lubricated and sealed with magnetic fluids such as: magnetic fluid bearing bushing made of magnetizable material, pivot bearings with porous sleeve impregnated with ferrofluid, self‐aligning bearings, hydrodynamic ferrofluid bearings with spiral and herringbone grooves structure are presented. Moreover, examples are shown of applications in modern bearing technology.

The paper provides information about new designs of magnetic fluid sliding bearings assemblies and gives the main advantages of these bearings over conventional ball bearings, such as extremely low non‐repetitive run‐out (high‐accuracy of rotation), good damping and quietness of operation, maintenance free service and high reliability.

This paper offers some new designs of compact, low friction and self‐contained magnetic fluid sliding bearings and points up their practical applications.

Proposing a new type of water-lubricated thrust bearing meets the load-bearing requirements of high-power shaft-less rim driven thrusters.

The designs were tested by establishing a bearing thermal-fluid-magnetic comprehensive simulation model and developing bearing fluid film force and magnetic simulation. Lubrication performance tests were carried out on the bearing test rig.

The Halbach array of magnet blocks is able to reach the maximum magnetic force. The material of sheath can help increase the magnetism. The magnetism is able to reduce wear during low-speed and the start-stop phase, while the eddy current loss at high speeds will lead to a decrease in magnetic force. The experiment found that the bearing was more stable at low speeds and would not demagnetize due to the temperature rise, but it is necessary to pay attention to the running stability at high speeds to prevent rubbing and impact.

An innovative combination of hydrodynamic pressure and permanent magnetic repulsion was observed to form a magnetic-liquid double suspension bearing with large bearing capacity.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2020-0295

To present some new designs of magnetic fluid exclusion seals for rolling bearings and possibility to use them in modern industrial sealing applications.

In the paper is given principle of magnetic fluid sealing technology and are presented new designs of magnetic fluid exclusion seals for rolling bearings, such as compact magnetic fluid seals, two‐stages seals being combination of magnetic fluid seal and labyrinth seal or radial lip seal, magnetic fluid seals with “floating” magnetic system. This paper also shows examples of their application in various rotating process equipment.

Provides information about new designs of bearing seals and gives the main advantages of these seals over other types, such as total tightness, low viscous drag, maintenance‐free service and high reliability.

This paper offers some new designs of high‐performance magnetic fluid exclusion seals for rolling bearings and points their practical applications.

This paper aims to investigate the performance of a ferrofluid-based hydrodynamic journal bearing system.

This paper presents a new design of ferrofluid-based hydrodynamic journal bearing. An experimental set-up consisting of a magnetic shaft along with a brass bearing was modified and developed. A permanent magnet was used to make the selected shaft material magnetic. The load and speed were varied to conduct the analyses for different test conditions.

The paper provides information about a design of ferrofluid-based journal bearing and its improved performances. For moderate to higher loads at different shaft speeds, it was found that because of the magnetization effect, the maximum film pressure in case of a ferrofluid lubricant increased up to approximately 60 per cent, compared with that of the conventional lubricant-based journal bearing system. Besides, the temperature rise was found smaller for ferrofluid lubricants, thus making the system cooler while running.

This paper offers a new design of magnetic bearing system for the experimental analysis by utilizing a magnetic shaft with a non-magnetic bearing. The present ferrofluid-based bearing design is less complicated from manufacturing point of view.

The porous bearings are commonly used in slider thrust bearings owing to their self-lubricating properties and cost effectiveness as compared to conventional hydrodynamic bearings. The purpose of this paper is to numerically investigate usefulness of porous layer in hydrostatic thrust bearing operating with magnetic fluid. The effect of magnetic field and permeability has been analysed on steady-state (film pressure, film reaction and lubricant flow rate) and rotor-dynamic (stiffness and damping) parameters of bearing.

Finite element approach is used to obtain numerical solution of flow governing equations (Magneto-hydrodynamics Reynolds equation, Darcy law and capillary equation) for computing abovementioned performance indices. Finite element method formulation converts elliptical Reynolds equation into set of algebraic equation that are solved using Gauss–Seidel method.

It has been reported that porosity has limited but adverse effects on performance parameters of bearing. The adverse effects of porosity can be minimized by using a circular pocket for achieving better steady-state response and an annular/elliptical pocket, for having better rotor-dynamic response. The use of magnetic fluid is found to be substantially enhancing the fluid film reaction (53%) and damping parameters (55%).

The present work recommends use of circular pocket for achieving better steady-state performance indices. However, annular and elliptical pockets should be preferred, when design criteria for the bearing are better rotor-dynamic performance.

This study deals with influence of magnetic fluid, porosity and pocket shape on rotor-dynamic performance of externally pressurized thrust bearing.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0289/

Recent interest in high temperature lubrication, in particular liquid metal lubrication, has prompted an investigation of the possible use of hydromagnetic effects to increase bearing pressurisation and load capacity. It has been found that by applying an external magnetic field along with an external current source a significant increase in pressurisation can be achieved over the hydrodynamical bearing. With the application of a magnetic field alone, that is under open circuit conditions, no appreciable pressurisation can be achieved except for extremely large magnetic fields. Several bearing geometries are analysed, the journal bearing, thrust bearing, and slider bearing, all with the same general conclusions. Various possible magnetic field and electrode configurations are discussed.

This paper aims to study the clearance compatibility of active magnetic bearing (AMB) and gas bearing (GB) to achieve a single-structured hybrid gas-magnetic bearing (HGMB), which uses a single bearing structure to realize both the functions of gas bearing and magnetic bearing.

Because the radial clearance size of the AMB is typically ten times larger than that of the GB, radial clearance compatibility of GB and AMB needs to maximize the radial clearance of GB by adjusting structural parameters. Parametric analysis of structural parameters of GB is explored. Furthermore, a general structural design principle based on static analysis, rotordynamic performance and system stability is established for the single-structured HGMB.

Load capacity is vastly reduced due to the enlarged radial clearance of the GB. A minimum clearance needs to be ensured by increasing the bearing diameter or width to compensate for the reduced load capacity, yet indirectly raising the bearing load. Increased bearing load is conducive to stability, yet it raises the risk of rotor abrasion. In addition, excessively large bearing diameter leads to system instability, and inappropriate bearing width affects critical speeds. A general structural design principle is established and the designed HGMB–rotor processes optimal performances.

A single-structured HGMB is proposed to address the urgent demand for high-speed, cryogenic turboexpanders with frequent starts/stops. This design applies a single-bearing structure to realize the characteristics of both GB and AMB, greatly simplifying the implementation, reducing air friction loss and raising critical speeds. This paper provides a fresh perspective on the development of cryogenic turboexpanders for hydrogen liquefaction. It theoretically validates the feasibility and provides a design guide for a single-structured HGMB system.

HAVING looked at all the problems that one may find in lubrication and wear, one may dream of a bearing which would have no contact between the rotating and static parts: the magnetic bearing is one such dream.

The purpose of this paper is to analyze the unbalanced magnetic pull (UMP) of the rotor of traction motor and the influence of the UMP on thermal characteristics of traction motor bearing.

The unbalanced magnetic pull on the rotor with different eccentricity was calculated by Fourier series expansion method. A bearing thermal analysis finite element model considering both the vibration of high-speed train caused by track irregularity and the UMP of traction motor rotor was established. The validity of the model is verified by experimental data obtained from a service high-speed train.

The results show that thermal failure of bearing subassemblies most likely occurs at contact area between the inner ring and rollers. The UMP of rotor of traction motor has a significant effect on the temperature of the inner ring and roller of the bearing. When the eccentricity is 10%, the temperature can even be increased by about 12°C. Therefore, the UMP of rotor of traction motor must be considered in thermal analysis of traction motor bearing.

In the thermal analysis of the bearing of the traction motor of high-speed train, the UMP of the rotor of the traction motor is considered for the first time

This paper aims to numerically investigate the influence of magnetic field and recess configurations on performance of hydrostatic thrust bearing. Electrically conducting fluid is supplied to bearing, operating in external magnetic field. Influences of recess geometric shapes (circular, rectangular, elliptical and triangular) and restrictor (capillary and orifice) are numerically examined on stead-state and dynamic performance characteristics of bearing.

Numerical simulation of hydrostatic thrust bearing has been performed using finite element (FE) method based on Galerkin’s technique. An iterative source code based on FE approach, Gauss–Siedel and Newton–Raphson method is used to compute steady-state and dynamic performance indices of bearings.

The presence of magnetic field is observed to be enhancing load-carrying capacity and damping coefficient of bearings. The effect is observed to be more pronounced at low value of Hartmann number, because of the saturation effect observed at higher values of Hartmann number. The enhancement in abovementioned performance indices is observed to be highly dependent on geometry of recess and restrictor.

This study presents a FE-based approach to numerically simulate a hydrostatic thrust bearing. It will help bearing designers and academician in selecting an appropriate recess shape, restrictor and strength of magnetic field, for obtaining optimum performance from hydrostatic thrust bearing.

The present investigation provides a coupled solution of modified Reynolds equation and restrictor equation, which is essential for accurately predicting the performance of hydrostatic thrust bearings.