Two-lobe pressure dam bearings are commonly used in high speed rotating machineries. Their use is considered more stable than plain cylindrical bearings. Such bearings have a dam in the upper half whereas the lower half is provided with a relief track. Performance of two-lobe pressure dam bearings under micropolar fluid is evaluated. Finite element method is used to solve the modified Reynolds equation. Fluid film pressures are obtained by solving modified Reynolds equation. Thus pressure obtained is used to find performance characteristics of this bearing. The dynamic performance characteristics are studied at variousL/Dratios. ThreeL/Dratios are considered 1.6, 2.0, and 2.4 for the analysis purpose. Results obtained are presented for various micropolar parameters. Results show that stability of two-lobe pressure dam bearings increases with decrease in aspect ratio (L/D).

The plain circular journal bearings are not found to be stable by researchers when used in high speed rotating machineries. Hence, extensive research in the study of stability characteristics of non-circular bearings or lobed bearings assumed importance, of late. Present article deals with the stability analysis of non-circular offset bearing by taking selected set of input and output parameters. Modified Reynolds equation for micropolar lubricated rigid journal bearing system is solved using finite element method. Two kinds of input parameters namely, offset factors (0.2, 0.4) and aspect ratios (1.6, 2.0) have been selected for the study. The important output characteristics such as load, critical mass, whirl frequency ratio, and threshold speed are computed and plotted for various set of values of input parameters. The results obtained indicate that micropolar lubricated circular offset bearing is highly stable for higher offset factor and higher aspect ratio.

A circular bearing experiences the instability problem due to oil whirl, causing violent vibrations at high speed. Two-lobe pressure dam bearing is a solution to the instability arising in high-speed rotating machineries. The paper presents the various static and dynamic characteristics of two-lobe pressure dam bearings, while operating with micropolar fluid. The modified Reynolds equation used to model the lubrication is solved using the finite element method. Performance characteristics such as load, attitude angle, critical mass, threshold speed and whirl frequency are computed, presented graphically and analysed. A detailed comparison of the performance characteristics is done for various micropolar and dam parameters. It is concluded that bearing performance is significantly influenced by dam parameters (dam angles) and micropolar parameters (coupling number and characteristics length).

In this research paper, the theoretical performance of a circular offset bearing is evaluated. The objective of this paper is to discuss the effects of eccentricity ratios and micropolarity parameters on the static and dynamic characteristics of an offset bearing with respect to micropolar lubrication. The modified Reynolds' equation for a dynamic state is solved using the finite-element method and Galerkin technique. The performance of an offset bearing is computed for a chosen range of eccentricity ratios (0.4–0.6) and for a length–diameter ratio (2.4). Enhancement in the performance of a bearing system is achieved in terms of increasing load and decreasing whirling at the higher values of eccentricity and offset especially at higher micropolarity.

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