РАДИАЛЬНОЕ ОБЖАТИЕ ПОРИСТЫХ ВТУЛОК ИЗ ЖЕЛЕЗO-СТЕКЛА, УПРОЧНЯЕМЫХ В ЖЕСТКОЙ ОПРАВКЕ

The article discusses the radial reduction of porous bushings made of powder composite material "iron-cast iron-glass", hardened in a rigid mandrel, which is an energetically more favorable process.It was found that during radial compression of porous bushings in a rigid mandrel, the density of the body being compacted is uniformly distributed along the radius. The result obtained in this case can be considered as an initial approximation to the true solution of the problem, which is found by the iteration method. Keywords: radial, reduction, porous, sleeve, mandrel, density, compaction, uniformly, method, iteration.

Flows and Their Stability in Rotating Cylinders With a Porous Lining

Flow fields in an annulus between two rotating cylinders with a porous lining have been numerically examined in this study. While the outer cylinder is stationary, the inner cylinder is rotating with a constant angular speed. A homogeneous and isotropic porous layer is press-fit to the inner surface of the outer cylinder. The porous sleeve is saturated with the fluid that fills the annulus. The effects of porous sleeve thickness and its properties on the flows and their stability in the annulus are numerically investigated. Three-dimensional momentum equations for the porous and fluid layers are formulated separately and solved simultaneously in terms of velocity and vorticity. The solutions have covered a wide range of the governing parameters (10−5≤Da≤10−2, 2000≤Ta≤5000, 0.8≤b¯≤0.95). The results obtained show that the presence of a porous sleeve generally has a stabilizing effect on the flows in the annulus.

Flow Stability in Rotating Cylinders With a Porous Lining

The effects of porous sleeve properties on the flow stability in rotating cylinders are numerically investigated in this study. To this end, three-dimensional momentum equations for the porous and fluid layers are formulated separately in terms of velocity and vorticity. These equations are then numerically solved over a wide range of parameters (10−2 ≤ Da ≤ 10−5, 2000 ≤ Ta ≤ 5000) to determine the critical Taylor number for the onset of flow instability for various porous sleeve properties. The results obtained show that the presence of a porous sleeve in general has a stabilizing effect on the flow in the annulus.

Flows Between Rotating Cylinders With a Porous Lining

Flow and temperature fields in an annulus between two rotating cylinders have been examined in this study. While the outer cylinder is stationary, the inner cylinder is rotating with a constant angular speed. A homogeneous and isotropic porous layer is press fit to the inner surface of the outer cylinder. The porous sleeve is saturated with the fluid that fills the annulus. The Brinkman-extended Darcy equations are used to model the flow in the porous layer while the Navier–Stokes equations are used for the fluid layer. The conditions applied at the interface between the porous and fluid layers are the continuity of temperature, heat flux, tangential velocity, and shear stress. Analytical solutions have been attempted. Through these solutions, the effects of Darcy number, Brinkman number, and porous sleeve thickness on the velocity profile and temperature distribution are studied.

Flows in Rotating Cylinders With a Porous Lining

Flow and temperature fields in an annulus between two rotating cylinders have been examined in this study. While the outer cylinder is stationary, the inner cylinder is rotating with a constant angular speed. A homogeneous and isotropic porous layer is press-fit to the inner surface of the outer cylinder. The porous sleeve is saturated with the fluid that fills the annulus. The Brinkman-extended Darcy equations are used to model the flow in the porous layer while Navier-Stokes equations are used for the fluid layer. The conditions applied at the interface between the porous and fluid layers are the continuity of temperature, heat flux, tangential velocity and shear stress. Analytical solutions have been attempted. Through these solutions, the effects of Darcy number, Brinkman number, and porous sleeve thickness on the velocity profile and temperature distribution are studied.

Numerical Analysis of a Coupled Porous Journal and Thrust Bearing System

A numerical model has been developed to analyze both static and dynamic characteristics of a coupled porous journal and thrust bearing system that is used to support a rotating shaft in a magnetic hard disk drive. The analyzed system is composed of a porous sleeve, a herringbone-grooved solid thrust plate and a flanged shaft, where the bottom end is closed to form a cantilever spindle. The inner surface and the bottom face of the porous sleeve operate as a herringbone-grooved journal and thrust bearing, respectively. The model is based on the narrow groove theory for the bearing oil film, and Darcy’s law for the internal flow in the porous sleeve. The pressure distribution, static equilibrium position of the shaft and dynamic coefficients are obtained under a given external axial load. There exists a window of permeability of the porous sleeve that presents significant advantage to prevent the creation of a sub-ambient condition and to maintain a large thrust bearing film thickness at the expense of some loss of dynamic performance.

Mixed Convection in Rotating Concentric Annulus With a Porous Sleeve

Numerical solutions are presented for mixed convection in rotating concentric cylinders with a porous sleeve. The porous sleeve is press-fitted to the inner surface of the outer cylinder. While the inner cylinder is rotating at a constant speed, the outer cylinder remains stationary. The main objective of the present study is to numerically investigate the flow pattern and temperature distribution as affected by the presence of the porous layer, the centrifugal force, and thermal buoyancy. A parametric study has been performed to investigate the effects of Peclet number, Rayleigh number, and Darcy number on the heat transfer results.