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Porous gas bearings (PGBs) have a proactive application in aerospace and turbomachinery. This study investigates the gas lubrication performance of a PGB with the condition of velocity slip boundary (VSB) owing to the high Knudsen number in the gas film. The Darcy-Forchheimer laws and modified Navier-Stokes equations were adopted to describe the gas flow in the porous layer and gas film region, respectively. An improved bearing experimental platform was established to verify the accuracy of the derived theory and the reliability of the numerical analysis. The effects of various parameters on the pressure distribution, flow cycle, load capacity, mass flow rate, and velocity profile are demonstrated and discussed. The results show that the gas can flow in both directions, from the porous layer to the gas film region, or in reverse. The load capacity of the PGB increases with an increase in speed and inlet pressure and decreases with an increase in permeability. The mass flow rate increases as the inlet pressure and permeability increase. Furthermore, the simulation results using VSB are in agreement with the experimental results, with an average error of 3.4%, which indicates that the model using VSB achieves a high accuracy. The simulation results ignoring the VSB overrate the load capacity by 16.42% and undervalue the mass flow rate by 11.29%. This study may aid in understanding the gas lubrication mechanism in PGBs and the development of novel gas lubricants.


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Investigation into gas lubrication performance of porous gas bearing considering velocity slip boundary condition

Show Author's information Xiangbo ZHANG1,2Shuiting DING2,3Farong DU2,3( )Fenzhu JI4Zheng XU1,2Jiang LIU4Qi ZHANG4Yu ZHOU2,3( )
School of Energy and Power Engineering, Beihang University, Beijing 100191, China
Aircraft/Engine Integrated System Safety Beijing Key Laboratory, Beihang University, Beijing 100191, China
Research Institute of Aero-Engine, Beihang University, Beijing 100191, China
School of Transportation Science and Engineering, Beihang University, Beijing 100191, China

Abstract

Porous gas bearings (PGBs) have a proactive application in aerospace and turbomachinery. This study investigates the gas lubrication performance of a PGB with the condition of velocity slip boundary (VSB) owing to the high Knudsen number in the gas film. The Darcy-Forchheimer laws and modified Navier-Stokes equations were adopted to describe the gas flow in the porous layer and gas film region, respectively. An improved bearing experimental platform was established to verify the accuracy of the derived theory and the reliability of the numerical analysis. The effects of various parameters on the pressure distribution, flow cycle, load capacity, mass flow rate, and velocity profile are demonstrated and discussed. The results show that the gas can flow in both directions, from the porous layer to the gas film region, or in reverse. The load capacity of the PGB increases with an increase in speed and inlet pressure and decreases with an increase in permeability. The mass flow rate increases as the inlet pressure and permeability increase. Furthermore, the simulation results using VSB are in agreement with the experimental results, with an average error of 3.4%, which indicates that the model using VSB achieves a high accuracy. The simulation results ignoring the VSB overrate the load capacity by 16.42% and undervalue the mass flow rate by 11.29%. This study may aid in understanding the gas lubrication mechanism in PGBs and the development of novel gas lubricants.

Keywords: numerical simulation, flow characteristics, porous gas bearing (PGB), velocity slip boundary (VSB), gas lubrication

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Publication history
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Publication history

Received: 19 August 2020
Revised: 27 January 2021
Accepted: 17 February 2021
Published: 05 June 2021
Issue date: June 2022

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© The author(s) 2021.

Acknowledgements

This study was funded by the National Natural Science Foundation of China (Grant Nos. 51775025 and 51175018), China Automobile Industry Innovation and Development Joint Fund (Grant No. U1664257), China Key Research and Development plan (Grant Nos. 2017YFB0102102 and 2018YFB0104100), and the Beijing Natural Science Foundation (Grant No. 3113030).

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