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CFD-FSI analysis of textured journal bearing working with nano lubricant

Hameed Mohanad Ramadhan, Ali Sarmad Ahmed, Hadwan Hamid Hussain, Toman Ahmed Ali, Mahdi Mushrek A.

Diagnostyka

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2024

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Vol. 25, No. 2

art. no. 2024212

EN

This research aims to examine the compound impact of adding rectangular textures to various zones on the surface of the bearing and nanoparticles in the lubricant on the properties of journal bearing. A lubrication models with various texture depths and eccentricity ratios of journal bearing are created and simulated using CFD-FSI method to get static properties like load capacity and frictional force. Aluminum oxide nanoparticles were added in weight ratios ranging from 0.1 to 0.5 %, and the change in viscosity due to these additives in the lubricant was considered. Cavitation and the dependence of viscosity on temperature effects are also considered. The validation results show that the acquired results from the current simulation method agree well with the experimental results in the reference. The outcomes indicated that the highest load capacity and the lowest frictional force are found in the high-pressure region. It was noted that the maximum rise in load capacity was 16.51% without nanoparticles at a texture depth of 0.5 mm and eccentricity ratio of 0.1, and with the adding of 0.5 wt. % of nanoparticles to the lubricant in the same region, the load carrying capacity increased to 40.87 % compared to a bearing without textures.

2

Effect of lubricant compressibility and variable viscosity on the performance of three-lobe journal bearing

Mahdi Mushrek A., Abass Basim Ajeel

Archive of Mechanical Engineering

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2022

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LXIX, nr 2

203–-219

EN

Different configurations of journal bearings have been extensively used in turbo- machinery and power generating equipment. Three-lobe bearing is used due to its lower film temperature and stable operation. In this study, static performance of such a bearing has been investigated at different eccentricity ratios considering lubricant compressibility and variable viscosity. The effect of variable viscosity was considered by taking the viscosity as a function of the oil film thickness while Dowson model is used to consider the effect of lubricant compressibility. The effect of such parameters was considered to compute the oil film pressure, load-carrying capacity, attitude an- gle and oil side leakage for a bearing working at (ε from 0.6 to 0.8) and (viscosity coefficient from 0 to 1). The mathematical model as well as the computer program prepared to solve the governing equations were validated by comparing the pressure distribution obtained in the present work with that obtained by EL-Said et al. A good agreement between the results has been observed with maximum deviation of 3%. The obtained results indicate a decrease in oil film pressure and load-carrying capacity with the higher values of viscosity coefficient while the oil compressibility has a little effect on such parameters.

3

Effect of micro protrusions on the performance of elliptical journal bearings operating with couple stress lubricant

Abass Basim Ajeel, Mahdi Mushrek A.

Diagnostyka

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2021

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Vol. 22, No. 2

97--104

EN

Elliptical bearing is characterized by low induced temperature and high stability at higher speed in comparison with the cylindrical journal bearing. The performance of such bearings can be affected by the type of oil used and its surface properties. The main goal of this work is to study the surface micro protrusion effect on the steady state operation of elliptical journal bearing lubricated with couple stress lubricant. The modified Reynolds’ equation to take into account the effects of couple stress lubricant and micro protrusions of the bearing surfaces is solved using finite difference method. The governing equations were solved using a prepared FORTRAN computer program. Pressure distribution, load carrying capacity and coefficient of friction have been studied for a bearing in laminar flow regime. The mathematical model was validated by comparing pressure results for the elliptical bearing of the present work with that obtained by Hussain et al.(1996). The obtained results demonstrate that the lubricant pressure and the load carried by the bearing decrease for the bearing with higher ellipticity factor while the load carried by the bearing increases for the bearing with higher protrusions or when using a couple stress fluid with higher couple stress variable.