Current Challenges and Frontiers for the EHD Simulation of Journal Bearings: a Review

Allmaier, Hannes; Offner, Günter

doi:10.4271/2016-01-1856

Cited by 8 publications

(6 citation statements)

References 94 publications

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“…These pressure forces are applied as excitation loads to the mechanical system and vice versa the global motion and local deformation of the shell and journal surface influence the hydrodynamic calculation. As discussed in Allmaier and Offner, 21 this interaction needs a strong coupling for the solution of the equations. For the simulation of the mechanical system, the following formulation is used.…”

Section: Model For Temperature Calculationmentioning

confidence: 99%

Thermal analysis of hydrodynamic lubricated journal bearings in internal combustion engines

Lorenz

Offner

Knaus

2017

Proceedings of the Institution of Mechanical Engineers, Part K:

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Hydrodynamic journal bearings are essential components in the internal combustion engines. The prediction of their reliability, durability, and economy, and also of their friction loss power and wear, are of highest importance. For an appropriate representation of the hydrodynamic load-carrying capacity and also the friction behavior, the multibody dynamics of the contacting components, the shape of the contacting component surfaces, the amount of the available lubricant, and the properties of the lubricant itself are of importance. A Reynolds-averaged equation with laminar flow conditions in combination with a dry asperity contact model and a multibody dynamic simulation of the structural components is a typical modeling approach for that purpose. Furthermore, this paper shows a newly developed model for the temperature distribution in the lubricant and the bearing structures. It includes thermal interface conditions between these domains, which incorporates the asperity energy source and predicts the temperature in supply areas. The presented method is applied for a typical engineering task of a sensitivity analysis for oils with different viscosity index improvers in a main bearing of a four-cylinder inline diesel engine. The influence of the oil film temperature on the oil film viscosity and, therefore, on the load-carrying capacity is shown. Furthermore, the simplified two-dimensional approach is compared with a three-dimensional approach in terms of the obtained result. The presented results show similar accuracy of the two-dimensional approach compared to the equivalent three-dimensional case.

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Section: Model For Temperature Calculationmentioning

confidence: 99%

Thermal analysis of hydrodynamic lubricated journal bearings in internal combustion engines

Lorenz

Offner

Knaus

2017

Proceedings of the Institution of Mechanical Engineers, Part K:

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“…Detailed approaches such as the elastohydrodynamic (EHD) method [17] and computational fluid dynamics (CFD) [18] are used for modeling the detailed physics of a journal bearing. However, these methods usually require very high computation times for performing time domain analysis of journal bearings in complex systems, such as a wind turbine drivetrain.…”

Section: Journal Bearing Modelmentioning

confidence: 99%

“…Based on the mathematical transformations given in [17], the following expression for fy and fz can be obtained:…”

Section: Journal Bearing Modelmentioning

confidence: 99%

The influence of journal bearings on the gearbox dynamics of a 5 MW wind turbine drivetrain

Siddiqui,

Chodvadiya,

Luo

2023

J. Phys.: Conf. Ser.

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In recent years, journal bearings have been replacing roller bearings in wind turbine gearboxes, as they are believed to provide higher reliability compared with roller bearings. However, replacing roller bearings with journal bearings can drastically change the gearbox dynamics. Journal bearings have complex dynamics at different operating speeds, and, as a wind turbine operates at various speeds, it is vital to analyze the gearbox dynamics for the entire speed range. This contribution presents the dynamic response of a wind turbine gearbox when the roller bearings of the high-speed shaft are replaced with journal bearings. This is done by performing a comparative case study using a detailed multibody simulation (MBS) model of a 5 MW reference wind turbine drivetrain. A dynamic model of the journal bearings, developed in Simulink, is dynamically coupled with the 5 MW drivetrain MBS model using co-simulation. The simulation results for the gearbox vibration as well as gear forces are compared with the simulation results of the drivetrain model with roller bearings. The findings from this work will help in clarifying the advantages (or disadvantages) of using journal bearings instead of roller bearings in wind turbine gearboxes.

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“…In their review, physical models and solution methods were examined. Allmaier and Offner [22] also reviewed the elastohydrodynamic simulation of journal bearings. They addressed a wide range of topics such as polymer coatings, the mixed lubrication regime, the simulation of the thermal behavior and a low-viscosity lubricant.…”

Section: Introductionmentioning

confidence: 99%

Minimizing Misalignment Effects in Finite Length Journal Bearings

Jamali

Aljibori

Senatore

et al. 2022

Designs

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This paper focuses on a method to reduce the detrimental effects that occur due to the misalignment in journal bearings by approaching it with the more complete model of a finite length bearing. Such a drawback is quite common in industrial applications, and it is generally accepted that misalignment causes a significant thinning in the film thickness in the area that is close to the bearing edges. Therefore, removing a certain volume of material from the inner surface of the bearing (bushing) over a distance that is at the bearing edges provides an additional clearance to compensate for the clearance reduction that is due to misalignment. A numerical solution that is used in this work is based on the finite difference method where the Reynolds boundary conditions are considered in the solution scheme, thereby, using an iterative procedure to identify the cavitation zone. A three-dimensional misalignment model is incorporated in the solution in order to provide a more realistic presentation of the deviations and errors that there are in comparison with the ideal aligned case. It has been found in the present work that the edge modification increases the thickness of the lubricant layer considerably and reduces the pressure spikes that are associated with the presence of misalignment. The suggested design also reduces the coefficient of friction in comparison with that of the misaligned case. Furthermore, this method helps in reducing the asymmetry of the hydrodynamic pressure field that results from the misalignment. This method enables the operation of journal bearings over a wider range of misalignment levels without sacrificing the load-carrying capacity of the bearing by maintaining a relatively thicker layer of lubricant at the critical positions that are not so due to the effects of misalignment.

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Current Challenges and Frontiers for the EHD Simulation of Journal Bearings: a Review

Cited by 8 publications

References 94 publications

Thermal analysis of hydrodynamic lubricated journal bearings in internal combustion engines

Thermal analysis of hydrodynamic lubricated journal bearings in internal combustion engines

The influence of journal bearings on the gearbox dynamics of a 5 MW wind turbine drivetrain

Minimizing Misalignment Effects in Finite Length Journal Bearings

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