Analysis of Misalignment Effects on Hydrodynamic Non-circular Journal Bearings Using Three-Dimensional Lattice Boltzmann
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RESEARCH PAPER
Analysis of Misalignment Effects on Hydrodynamic Non-circular Journal Bearings Using Three-Dimensional Lattice Boltzmann Method Zoheir Saboohi1
•
Shayan Roofeh2 • MohammadReza Salimi1
Received: 8 April 2020 / Accepted: 7 October 2020 Shiraz University 2020
Abstract In this paper, a numerical model for prediction of hydrodynamic non-circular journal bearings considering misalignments is proposed. The misalignment effects on non-circular hydrodynamical journal bearings are studied. For analyzing journal’s hydrodynamic film, the LBM method, instead of prevalent CFD methods, has been used; since the LBM method has local behavior, it is suitable for parallelization. Previous numerical and analytical works on this subject have been used for validation, and it is found that the LBM results are reasonably accurate. The simulation for different misalignment factors and preload factors is performed. It is revealed that misalignment can increase the maximum pressure of the bearing up to nearly two times the aligned journal bearing; thus, misalignment is an important parameter in the design and analysis of hydrodynamic journal bearing. Keywords Journal bearing Film thickness Hydrodynamic lubrication Mesoscopic List Cp Cs Ci ep e f fi h h* F M P P* Pf Q R r S t
of Symbols Pad clearance Speed of sound Discrete velocity Ellipticity of bearing Eccentricity Distribution function Population function Oil’s film thickness Non-dimensional oil’s film thickness Load capacity Transformation matrix Pressure Non-dimensional pressure Preload factor Lubricant flow Radius of pad Radius of journal Diagonal collision matrix Misalignment parameter
& Zoheir Saboohi [email protected] 1
Aeospace Research Institute (ARI), Ministry of Science, Research, and Technology, Tehran, Iran
2
Amirkabir University of Technology (AUT), Tehran, Iran
Greek Letters f Bulk viscosity e Non-dimensional bearing eccentricity t Kinematic viscosity q Density g Dynamic viscosity X Collision operator [ Attitude angle
1 Introduction Nowadays, the hydrodynamic journal bearings are frequently used in turbomachinery industries. Journal bearings supported high-speed shafts and/or heavy loads in the rotor dynamic systems; thus, these bearings have been studied by many different approaches, and it is necessary to determine static and dynamic characteristics of journal bearings precisely and consider performance parameters carefully (Pierre et al. 2004). Due to film’s small thickness, misalignment is one of the significant parameters affecting the bearing performance. The misalignment phenomenon in journal bearings can result from elastic deformation of the journal during operation, non-central loading, manufacturing and/or assembly errors in the bearings, and thermal distortion of the shaft. Moreover, it could cause significant defects in bearings dynamics and even harmful damages (Pierre et al.
123
Iran J Sci Technol Trans Sci
2004). Journal misalignment can have significant and frequently harmfu
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