Offset-halves journal bearings Fig. For each bearing configuration, the use of grade Oil 2 gives, the minimum temperature rise, and power losses which implies that the oil with low viscosity should be preferred as compared to high viscosity oil from thermal point of view and temperature rise is low for offset-halves bearing.
This feature accounts for the superior stiffness, damping, and reduced temperature in the oil film as compared to the circular journal bearings. The solution of governing equations has been achieved by satisfying the convergence criterion given below:. It was observed that the temperature approximation across the film thickness by Legendre Polynomial yields more accurate results in comparison to Parabolic Profile approximation.
The temperature in bush is determined by using the Laplace equation within the bearing material as given below Hori [ 2006 ]:.
In earlier works, the bearing performance parameters have been computed by solving the Reynolds equation only. If the equipment is operated at full power, these requirements can be met by lemon bore bearings. Here, C P represents specific heat of the lubricating oil, K represents thermal conductivity of the lubricating oil, and u , w represents velocity components in X- and Z-directions.
However, the former is algebraically more complex to tackle in comparison to the later; the authors also observed that the film temperatures computed by Parabolic Profile approximation are lower in comparison to Legendre Polynomial approximation. The overview of both the circular and non-circular hydrodynamic journal bearings and their design methodologies are discussed as follows:. Tayal et al. Pressure also influences the viscosity of the lubricant to certain extent.
This section of the chapter provides details of research carried out on hydrodynamic bearings in general and, offset-halves and elliptical journal bearings in particular.
It can be concluded from the above discussion that the lubricating oil with higher viscosity value results in high oil film temperature rise, high thermal pressure, high load capacity and also high power loss value, whereas the lubricating oil with low viscous value results in low oil film temperature rise, low thermal pressure, little low load capacity and power loss value.
Hence, the overall oil film temperature rise and thermal pressure has been observed high for elliptical journal bearing. Simple form of this bearing offers many advantages in its manufacturing as well as in its performance. An attempt has been made to compare the performance of two bearing configurations namely: There is no vertical flow across the film. The basic configuration of the circular journal bearing consists of a journal which rotates relative to the bearing which is also known as bush Fig.
It has been reported by the authors that the offset bearing runs cooler than an equivalent circular bearing with axial grooves. Sharma and Pandey [ 2007 ] have carried out a thermohydrodynamic lubrication analysis of infinitely wide slider bearing assuming parabolic and Legendre polynomial temperature profile across the film thickness.
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Performance Evaluation of Bearings. Body forces are neglected i. Numerical techniques for the thermal analysis of non-circular journal bearing In earlier works, the bearing performance parameters have been computed by solving the Reynolds equation only. In this equation, r stands for bush radius, and T b stands for bush temperature.
Ma and Taylor [ 1996 ] experimentally investigated the thermal behaviour of a two-axial-groove circular bearing and an elliptical bearing, both 110mm in diameter. Help us write another book on this subject and reach those readers.