The performance of non-circular bearings, such as multi-lobe bearings is influenced by many bearing parameters such as the number of lobes, the preload factor, and the tilt angle. In this study, the effects of bearing preload factor on the static performance characteristics of micropolar lubricated two-, three-, and four-lobe bearings are investigated. For this purpose, modified Reynolds equation for micropolar fluids is solved by FEM, to find the fluid film pressure. Then, in turn, bearing performance characteristics, namely, load-carrying capacity, attitude angle, frictional force, friction coefficient, and side leakage flow are calculated. Results show that, in general, micropolarity of the lubricant improves the performance of the bearings; however, non-circularity parameter of the lobe of the bearings, preload, has a favourable effect on certain performance characteristics of the bearings, such as the attitude angle which decreases as non-circularity of the bearing increases. The results further show that the rate of influence of preload factor on the performance characteristics of different lobed bearings is not the same.
In contrast to plain circular bearings, orientation of the lobe bearings with respect to a fixed load direction can influence the bearing performance characteristics. Expressing the lobe bearing orientation in terms of an angle, which in this study is referred to as bearing orientation angle, its effect on static performance characteristics of three types of micropolar lubricated lobe bearings is investigated. For this purpose, finite element method is adopted for numerical solution of the modified Reynolds equation. It is found that against the most common mode of the lobe bearing orientation, which is with the bearing orientation angle zero, performance of the lobe bearings can be improved by suitable selection of the bearing orientation angle. Also, lobe bearings with comparatively lesser number of lobes are more affected by the orientation angle.
Purpose -The purpose of this paper is to analyse the static performance characteristics of lobe journal bearings lubricated with a micropolar fluid, considering effect of non-circularity. Number of lobes and their preload value are the non-circularity parameters considered in the present study. The bearings undertaken for the investigation are two, three and four-lobe symmetric journal bearings with finite width. Design/methodology/approach -For this purpose, modified form of Reynolds equation is derived, based on Eringen's micropolar fluid theory and it is solved numerically using finite element method (FEM). The effect of the non-circularity parameters of bearings on the steady-state performance characteristics such as load carrying capacity, attitude angle, coefficient of friction and side leakage flow are presented and discussed.Findings -The results show that the number of lobes and their preload value can influence the performance of lobe bearings. It is seen that, in order to provide certain improvement over simple cylindrical bearings, the non-circularity parameters of lobe bearings must be chosen correctly. There is no single optimum profile for multi-lobe bearing application. Originality/value -Lobe bearings, compared with simple circular bearings, offer several geometric parameters to designers. These parameters must be chosen correctly, so that the requirements of a specific application can be fulfilled.
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