The present work is on prediction of temperature distribution in noncircular journal bearings and the surrounding solids. Three forms are studied, viz. two-lobe, elliptical and orthogonally displaced bearings. For comparison purposes, a circular bearing with two different groove locations is analyzed. The investigation includes the effects of recirculation and oil mixing at the grooves. The cavitation zone has also been investigated. The work is based on a two-dimensional treatment following McCallion’s approach. The results are presented for various geometries of journal bearing configuration, including the conventional circular bearing.
Recent studies of the cavitation zone in the journal bearing indicate that a sublayer of lubricant adheres to the journal surface. Based on this observation, it is proposed in the present work that centrifugal force and surface tension should be considered as the primary cause for the lubricant film to be in equilibrium in the cavitation zone. Using this concept a cavitation model is proposed. The effect of the supply pressure on fluid film reformation is also studied. The proposed model is applied to study the cavitation zone of: (1) a journal bearing with lubricant entry along the line of centers and (2) a journal bearing with inlet groove located along the load line. It is found that the thickness of the lubricant layer adhering to the journal surface is an exponential function of the speed while the eccentricity ratio rather than speed has a predominant effect on the width of the streamers. The supply pressure has a remarkable effect on the film reformation when the lubricant supply is along the line of centers, with the possibility of film reformation at the supply groove, which does not happen when the lubricant inlet is located along the load line.
Frictional brake lining materials are broadly made of asbestos as their constituent. But asbestos is dangerous for handling due to health hazardous. Asbestos has ample physical, mechanical and tribological properties. The material replacing it should have all these properties with no undermine. In this paper a study on asbestos base and asbestos free brake lining material is presented. Purpose behind this is combine the demerits of asbestos free and asbestos base materials with comparable properties. Some organic waste from farm like banana peel, palm karnel shell, were also tested for the replacement of asbestos and they found worth through comparison with each others.
Purpose -The aim of this paper is to develop a technique to measure the oil film thickness between piston ring and liner throughout the stroke, without impairing the surface properties of the piston ring and liner. Mechanical properties of the piston ring, like ring stiffness, are also not altered. Effect of variation in bore on the movement of piston ring can be studied with the proposed technique. Design/methodology/approach -The gap Hmin between the cylinder liner and the piston ring is formed due to the hydrodynamic pressure generated by the presence of oil film between piston ring and liner. This gap can be inferred by measuring the movement of the inner surface of piston ring with reference to a sensor mounted on the piston at a fixed distance from the piston ring. The piston ring is connected to the sensor through reasonably rigid member. The underlying assumption here is that there is no elastic deformation of the piston ring due to the hydrodynamic pressure. The fundamental sensor to measure oil film thickness used in this setup is a set of strain gauges. Findings -It is possible to measure oil film thickness by the proposed arrangement for the entire stroke without changing the surface properties. Mechanical properties of the piston ring, like ring tension, are not affected. The results possibly provide the correct picture of the piston ring movement throughout the stroke. The measurement at near zero speed can give information on the movement of the piston ring due to hydrodynamic action and to the variation in the bore. The measurement is not affected by engine vibrations. The proposed technique can be helpful in validating the theoretical models proposed in the literature. Originality/value -The measurement is possible only in unfired condition. However, this attempt can be considered as the basis to measure OFT in fired condition with necessary improvements. It is not feasible to measure quantity of lubricant/extent of lubricant on leading or trailing edge of piston. Effect of temperature on the oil film thickness cannot be studied as the engine is not fired. It is assumed that the piston ring does not pass through elasto-hydrodynamic lubrication regime. Debris/worn out particles in the oil may affect the indicated oil film thickness at local points.
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