Numerical modeling for gaseous cavitation of oil film and non-equilibrium dissolution effects in thrust bearings

Proceedings of the Institution of Mechanical Engineers, Part J:

2015

Self Cite

The prediction of cavitation in lubricants is of significance to the design and analysis of hydrodynamic bearings. In this paper, a numerical model for the gaseous cavitation in hydrodynamic lubrication problems is derived based on the cavitation mechanism and origination, which is different from the conventional cavitation conditions. The proposed gaseous cavitation model is then used to calculate the performance of several types of bearings, including a two-axially grooved plain journal bearing, a misaligned journal bearing and parallel thrust bearings with surface textures. The results are validated with experimental data and numerical results calculated by the Half-Sommerfeld, Reynolds, and JFO conditions. The advantage of this new model lies in its accuracy and its independence from the cavitation pressure, which is usually difficult to be accurately defined. Thus this gaseous cavitation model can be useful in the accurate prediction of the cavitation phenomenon and performance of hydrodynamic bearings under steady state.

Section: The Gaseous Cavitation Modelmentioning

confidence: 99%

Development and validation of a gaseous cavitation model for hydrodynamic lubrication

Song

Proceedings of the Institution of Mechanical Engineers, Part J:

2015

Self Cite

“…14,15 This model has been applied in many complex simulations, such as analyzing the nonequilibrium dissolution effect in thrust bearings. 16…”

Section: Introductionmentioning

confidence: 99%

“…14,15 This model has been applied in many complex simulations, such as analyzing the nonequilibrium dissolution effect in thrust bearings. 16 In addition to the cavitation models, the turbulence effect of bearing oil films on bearing numerical simulations has also been studied. Compared with the laminar simulation results and experimental data, the turbulence simulation results of the bearing oil films confirmed that the turbulence effect should be considered for bearing lubricant flows.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation for characteristics and oil–air distributions of oil film in a tilting-pad journal bearing

Ding

Proceedings of the Institution of Mechanical Engineers, Part J:

et al. 2019

This paper analyzes the effects of air in the oil film of a tilting-pad journal bearing on oil–air distributions and characteristics. With a gaseous cavitation model and shear stress transport model with low-Re correction included, the air backflow from the outlet boundary is analyzed in numerical simulations of a titling-pad journal bearing at 3000 r/min rotation speed and under 180 kN load. The simulated bearing load, pressure, and mechanical loss are in good accordance with the experimental data, indicating that the simulation results of the air backflow from the outlet boundary can catch the hydrodynamic characteristics accurately. Based on the turbulence viscosity ratio analysis, the turbulence effect cannot be ignored at the high rotational speed. With the comparison between the unloaded area and the loaded area, the boundary layer and turbulent flow develops with the film thickness increasing. Based on the analyses of simulated air volume fraction and pressure distribution, the gaseous cavitation occurs around the center part of the unloaded area, following the gaseous cavitation mechanisms. The backflow air flows into the low-pressure unloaded area from the outlet boundary and has a clear interval with the air from the gaseous cavitation. The air volume fraction increases with these two air sources and affects the mixture viscosity significantly, eventually influencing the shear stress on the rotor-side wall and bearing mechanical loss.

“…Two cavitation mechanisms have been compared under static and dynamic loads to identify the dominant mechanism [4][5][6]. A new model based on air solubility has also been proposed for gaseous cavitation [7,8] and improved by considering nonequilibrium dissolution for oil film in bearings [9]. A tapered land thrust bearing has also been utilized to verify the cavitation effect [10,11].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Turbulence Models for a Superlaminar Journal Bearing

Ding

et al. 2018

Advances in Tribology

With rotating machineries working at high speeds, oil flow in bearings becomes superlaminar. Under superlaminar conditions, flow exhibits between laminar and fully developed turbulence. In this study, superlaminar oil flow in an oil-lubricated tilting-pad journal bearing is analyzed through computational fluid dynamics (CFD). A three-dimensional bearing model is established. CFD results from the laminar model and 14 turbulence models are compared with experimental findings. The laminar simulation results of padside pressure are inconsistent with the experimental data. Thus, the turbulence effects on superlaminar flow should be considered. The simulated temperature and pressure distributions from the classical fully developed turbulence models cannot correctly fit the experimental data. As such, turbulence models should be corrected for superlaminar flow. However, several corrections, such as transition correction, are unsuitable. Among all the flow models, the SST model with low-Re correction exhibits the best pressure distribution and turbulence viscosity ratio. Velocity profile analysis confirms that a buffer layer plays an important role in the superlaminar boundary layer. Classical fully developed turbulence models cannot accurately predict the buffer layer, but this problem can be resolved by initiating an appropriate low-Re correction. Therefore, the SST model with low-Re correction yields suitable results for superlaminar flows in bearings.