Numerical investigation of static characteristic of a tilting-pad journal bearing using shear stress transport model and air backflow

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 (SST) 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 rpm 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 analyses of simulated air volume fraction and shear stress, the shear stress of the high-pressure loaded area is mainly influenced by the velocity gradient in the normal direction to the rotor-side wall, not the air backflow and gaseous cavitation. In the unloaded area, the gaseous cavitation occurs around the center part, 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.

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

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650119858241 ◽

2019 ◽

Vol 234 (2) ◽

pp. 193-204

Author(s):

Aoshuang Ding ◽

Xiaodong Ren ◽

Xuesong Li ◽

Chunwei Gu

Keyword(s):

Shear Stress ◽

Journal Bearing ◽

Volume Fraction ◽

Mechanical Loss ◽

Load Pressure ◽

High Rotational Speed ◽

Oil Film ◽

Air Volume ◽

Tilting Pad ◽

Tilting Pad Journal Bearing

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.

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Numerical investigation of the effect of manufacturing errors in pads on the behaviour of tilting-pad journal bearings

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650117721118 ◽

2017 ◽

Vol 232 (4) ◽

pp. 480-500 ◽

Cited By ~ 11

Author(s):

Phuoc Vinh Dang ◽

Steven Chatterton ◽

Paolo Pennacchi ◽

Andrea Vania

Keyword(s):

Sensitivity Analysis ◽

Numerical Investigation ◽

Journal Bearing ◽

Journal Bearings ◽

Tilting Pad ◽

Manufacturing Errors ◽

Manufacturing Tolerances ◽

Thickness Variations ◽

Tilting Pad Journal Bearing ◽

Tilting Pad Journal Bearings

In this study, the effect of the manufacturing tolerances of the pad thickness or the assembly errors on the characteristics of a five-pad tilting-pad journal bearing is analysed. In fact, the pad thickness errors correspond to a different preload factor or clearance for each pad. A sensitivity analysis was performed for several combinations of pad thickness for both load-on-pad and load-between-pad configurations using a thermo-elasto-hydro-dynamic model. Three cases of thickness variations were studied. The numerical results show that these manufacturing or assembly errors considerably affect on both the static and dynamic behaviours of the bearing.

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A Comparative Analysis of Turbulence Models Utilised for the Prediction of Turbulent Airflow through a Sudden Expansion

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.16.64 ◽

2015 ◽

Vol 16 ◽

pp. 64-78 ◽

Cited By ~ 1

Author(s):

Karinate Valentine Okiy

Keyword(s):

Shear Stress ◽

Convergence Rate ◽

Transport Model ◽

Turbulence Models ◽

Sudden Expansion ◽

Circular Duct ◽

Shear Stress Transport ◽

Shear Stress Transport Model ◽

Turbulent Airflow ◽

Recirculation Length

The turbulent airflow in a circular duct with sudden expansion was investigated utilizing three turbulence models. The turbulence models chosen are: the k-epsilon model, the shear stress transport model and the Reynolds-stress model. The performance of the models was investigated with respect to the flow parameter-recirculation length. The turbulent kinetic energy and velocity predictions were compared between the turbulence models and with experimental data, then interpreted on the basis of the recirculation length. From the results, the shear stress transport model predictions of recirculation length had the closest agreement with the experimental result compared to the other model. Likewise, the convergence rate for the shear stress transport model was reasonable compared to that of the Reynolds model which has the slowest convergence rate. In light of these findings, the shear stress transport model was discovered to be the most appropriate for the investigation of turbulent air flow in a circular duct with sudden expansion. Keywords: Turbulence, recirculation length, sudden expansion, Turbulence models.

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Roughness Corrections for the k–ω Shear Stress Transport Model: Status and Proposals

Journal of Fluids Engineering ◽

10.1115/1.4028122 ◽

2014 ◽

Vol 137 (2) ◽

Cited By ~ 22

Author(s):

B. Aupoix

Keyword(s):

Shear Stress ◽

Transport Model ◽

Wall Region ◽

Large Set ◽

Transition Regime ◽

Wall Roughness ◽

Shear Stress Transport ◽

Sst Model ◽

Shear Stress Transport Model ◽

Simplified Analysis

Various corrections were previously proposed to account for wall roughness with the k–ω and shear stress transport (SST) models. A simplified analysis, based upon the wall region analysis, is proposed to characterize the behavior of these roughness corrections. As this analysis points out some deficiencies for each correction, two new corrections are proposed for the SST model, to reproduce different behaviors, mainly in the transition regime. The correction development is based upon a previously developed strategy. A large set of boundary layer experiments is used to compare the different roughness corrections, confirm the failures of previous proposals, and validate the present ones. Moreover, it assesses the proposed simplified analysis. It also evidences the difficulty to determine the equivalent sand grain roughness for a given surface. The Colebrook based correction is recommended while the Nikuradse based one can add information about the envelope of possible behaviors in the transition regime.

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