scholarly journals Hydrostatic Bearing Characteristics Investigation of a Spherical Piston Pair with an Annular Orifice Damper in Spherical Pump

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1007
Author(s):  
Dong Guan ◽  
Zhuxin Zhou ◽  
Chun Zhang
Keyword(s):  
Direct Contact ◽  
Reynolds Equation ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Flow Rates ◽  
Hydrostatic Bearing ◽  
High Efficient ◽  
Load Carrying ◽  
Piston Pair ◽  
Stiffness Variation

The spherical pump is a totally new hydraulic concept, with spherical piston and hydrostatic bearing, in order to eliminate the direct contact between the piston and cylinder cover. In this paper, the governing Reynolds equation under spherical coordinates has been solved and the hydrostatic bearing characteristics are systematically investigated. The operating sensitivities of the proposed spherical hydrostatic bearing, with respect to the piston radius, film beginning angle, film ending angle, film thickness, and temperature, are studied. The load carrying capacity, pressure drop coefficient, stiffness variation of the lubricating films, leakage properties, and leakage flow rates are comprehensively discussed. The related findings provide a fundamental basis for designing the high-efficient spherical pump under multiple operating conditions. Besides, these related results and mechanisms can also be utilized to design and improve other kinds of annular orifice damper spherical hydraulic bearing systems.

scholarly journals Manufacturing, Characterisation and Mechanical Analysis of Polyacrylonitrile Membranes

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2378
Author(s):  
Mertol Tüfekci ◽  
Sevgi Güneş Durak ◽  
İnci Pir ◽  
Türkan Ormancı Acar ◽  
Güler Türkoğlu Demirkol ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Main Idea ◽  
Mechanical Analysis ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
The Finite Element Method ◽  
Load Carrying ◽  
The Impact ◽  
Static Behaviour ◽  
Modelling Process

To investigate the effect of polyvinylpyrrolidone (PVP) addition and consequently porosity, two different sets of membranes are manufactured, since PVP is a widely used poring agent which has an impact on the mechanical properties of the membrane material. The first set (PAN 1) includes polyacrylonitrile (PAN) and the necessary solvent while the second set (PAN 2) is made of PAN and PVP. These membranes are put through several characterisation processes including tensile testing. The obtained data are used to model the static behaviour of the membranes with different geometries but similar loading and boundary conditions that represent their operating conditions. This modelling process is undertaken by using the finite element method. The main idea is to investigate how geometry affects the load-carrying capacity of the membranes. Alongside membrane modelling, their materials are modelled with representative elements with hexagonal and rectangular pore arrays (RE) to understand the impact of porosity on the mechanical properties. Exploring the results, the best geometry is found as the elliptic membrane with the aspect ratio 4 and the better RE as the hexagonal array which can predict the elastic properties with an approximate error of 12%.

Computational Fluid Dynamics Thermohydrodynamic Analysis of Three-Dimensional Sector-Pad Thrust Bearings With Rectangular Dimples

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
C. I. Papadopoulos ◽  
L. Kaiktsis ◽  
M. Fillon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Carrying Capacity ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Performance Indices ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Texture Design

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of computational fluid dynamics (CFD) simulations, based on the numerical solution of the Navier–Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth, and texture density on the bearing performance indices (load carrying capacity, friction torque, and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

The Validity of the Reynolds Equation in Modeling Hydrostatic Effects in Gas Lubricated Textured Parallel Surfaces

2005 ◽  
Vol 128 (2) ◽  
pp. 345-350 ◽  
Author(s):  
Y. Feldman ◽  
Y. Kligerman ◽  
I. Etsion ◽  
S. Haber
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Stokes Equations ◽  
Surface Texturing ◽  
Laser Surface Texturing ◽  
Physical Parameters ◽  
Load Carrying Capacity ◽  
Wide Range ◽  
Load Carrying ◽  
Parallel Surfaces

Microdimples generated by laser surface texturing (LST) can be used to enhance performance in hydrostatic gas-lubricated tribological components with parallel surfaces. The pressure distribution and load carrying capacity for a single three-dimensional dimple, representing the LST, were obtained via two different methods of analysis: a numerical solution of the exact full Navier-Stokes equations, and an approximate solution of the much simpler Reynolds equation. Comparison between the two solution methods illustrates that, despite potential large differences in local pressures, the differences in load carrying capacity, for realistic geometrical and physical parameters, are small. Even at large clearances of 5% of the dimple diameter and pressure ratios of 2.5 the error in the load carrying capacity is only about 15%. Thus, for a wide range of practical clearances and pressures, the simpler, approximate Reynolds equation can safely be applied to yield reasonable predictions for the load carrying capacity of dimpled surfaces.

Finite Element Analysis of the Static Performance of a Self-Slot-Compensating Aerostatic Bearing

2011 ◽  
Vol 199-200 ◽  
pp. 749-753
Author(s):  
Xiao Bo Zuo ◽  
Jian Min Wang ◽  
Chao Liang Guan ◽  
Juan Li
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Geometric Parameters ◽  
Load Carrying Capacity ◽  
The Finite Element Method ◽  
Aerostatic Bearing ◽  
Element Analysis ◽  
Consistent Condition ◽  
Load Carrying ◽  
Static Performance

The static performance of an aerostatic bearing with angled surface self-slot-compensation is analyzed. The consistent condition was applied to unitize the Reynolds equation of different forms and the finite element method (FEM) was used to solve the equation. The load carrying capacity (LCC) and the stiffness of the bearing was obtained and the influence of the geometric parameters was discussed. It is concluded that this self-compensating aerostatic bearing can achieve a good performance; the geometric parameters of the gap are interactive, and should be rationally matched.

Static and dynamic performance characteristics of powder lubricated symmetrical three-lobed bearing

2020 ◽  
pp. 135065012092632
Author(s):  
Jijo Jose ◽  
Niranjana Behera
Keyword(s):  
Carrying Capacity ◽  
Elevated Temperatures ◽  
Dynamic Performance ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Oil Degradation ◽  
Static And Dynamic Characteristics ◽  
Load Carrying ◽  
The Coefficient Of Friction ◽  
Ellipticity Ratio

Hydrodynamic oil bearings applied at elevated temperatures and extreme operating conditions are subjected to the problem of oil degradation. In order to overcome such conditions, dry powder lubricants are used as lubricants in the hydrodynamic journal bearings. Thus the problem of thermal degradation of oil at high temperatures can be eliminated. In this work, the static and dynamic characteristics of a symmetric three-lobed bearing lubricated with powdered particles have been predicted. Influence of the ellipticity ratio on the performance of the three-lobed bearing has also been investigated. It is observed that an increase in the ellipticity ratio increases the coefficient of friction and stability, but decreases the side leakage and the load carrying capacity of the three-lobed bearing. Also, it was observed that the large-sized powdered particles induce better load carrying capacity and better stability than the small-sized particles.

Analysis and comparative study of ferrofluid lubricated circular porous squeeze film-bearings

2017 ◽  
Vol 231 (11) ◽  
pp. 1450-1463 ◽  
Author(s):  
Rajesh C Shah ◽  
Dilip B Patel
Keyword(s):  
Magnetic Field ◽  
Reynolds Equation ◽  
Variable Magnetic Field ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Anisotropic Permeability ◽  
Load Carrying ◽  
Design Systems ◽  
Bearing Design ◽  
Maximum Field

Based on ferrohydrodynamic theory by R. E. Rosensweig and continuity equation for film as well as upper and lower porous regions, a general modified Reynolds equation for ferrofluid (FF) lubricated circular discs porous squeeze film-bearings is derived by assuming the validity of the Darcy’s law in the porous regions. The effects of porosity, slip velocity, anisotropic permeability and rotation at both the discs are also included for the study. Here, the FF is controlled by oblique and radially variable magnetic field. The effect of porosity is included because of its advantageous property of self-lubrication, and oblique variable magnetic field is important because of its advantage of generating maximum field at the required active contact zone of the bearing design systems. Using Reynolds equation, different circular porous squeeze film-bearing design systems (e.g. exponential, secant and parallel (flat)) are studied and compared for load-carrying capacity. During the course of investigation, it is observed that uniform magnetic field does not affect on the performances of the bearing systems.

Hydrodynamic Lubrication of Finite Slider Bearings: Effect of One Dimensional Film Shape, and Their Computer Aided Optimum Designs

1983 ◽  
Vol 105 (1) ◽  
pp. 48-63 ◽  
Author(s):  
C. Bagci ◽  
A. P. Singh
Keyword(s):  
Numerical Solution ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Design Data ◽  
Slider Bearings ◽  
Load Carrying ◽  
Computer Aided

The effect of the film shape on the load carrying capacity of a hydrodynamically lubricated bearing has not been considered an important factor in the past. Flat-faced tapered bearing and the Raileigh’s step bearing of constant film thickness have been the primary forms of film shapes for slider bearing studies and design data developments. This article, by the computer aided numerical solution of the Reynolds equation for two dimensional incompressible lubricant flow, investigates hydrodynamically lubricated slider bearings having different film shapes and studies the effect of the film shape on the performance characteristics of finite bearings; and it shows that optimized bearing with film shapes having descending slope toward the trailing edge of the bearing has considerably higher load carrying capacity than the optimized flat-faced tapered bearing of the same properties. For example the truncated cycloidal film shape yields 26.3 percent higher load carrying capacity for Lz/Lx = 1 size ratio, and 44 percent higher for Lz/Lx = 1/2. The article then presents charts for the optimum designs of finite slider bearings having tapered, exponential, catenoidal, polynomial, and truncated-cycloidal film shapes, and illustrates their use in numerical bearing design examples. These charts also furnish information on flow rate, side leakage, temperature rise, coefficient of friction, and friction power loss in optimum bearings. Appended to the article are analytical solutions for infinitely wide bearings with optimum bearing characteristics. The computer aided numerical solution of the Reynolds equation in most general form is presented by which finite or infinitely wide hydrodynamically or hydrostatically lubricated bearings, externally pressurized or not, can be studied. A digital computer program is made available.

Theoretical Analysis of Externally Pressurized Air Journal Bearing

1970 ◽  
Vol 12 (2) ◽  
pp. 123-129 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Experimental Data ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Dimensional Parameters ◽  
Bearing Design

A theoretical investigation is made to predict the performance of an externally pressurized air journal bearing having several pressure sources. The pressure distribution, which leads to the determination of load-carrying capacity and flow requirement, is obtained by solving Reynolds equation numerically. The load and flow, expressed in non-dimensional parameters, are presented for different bearing design parameters (dimensionless). The results predicted by this method are compared with others' experimental data.

Overall Characteristics of Bearings Lubricated With Ferrofluids

1983 ◽  
Vol 105 (3) ◽  
pp. 466-475 ◽  
Author(s):  
N. Tipei
Keyword(s):  
Boundary Conditions ◽  
Carrying Capacity ◽  
Magnetic Particle ◽  
Journal Bearings ◽  
Load Carrying Capacity ◽  
Pressure Center ◽  
Friction Forces ◽  
Flow Rates ◽  
Load Carrying ◽  
Side Flow

Using the results shown in some previous papers, the overall characteristics of bearings lubricated with ferrofluids are calculated. First, the load carrying capacity of infinitely long sliding and journal bearings is considered. The pressure center and the attitude angle are also determined. Then, similar characteristics of finite bearings are obtained. In both cases, the new boundary conditions and the actual film extent under magnetic stresses are taken into account. It is shown that friction forces are mainly affected by the change in viscosity due to magnetic particle suspensions, while magnetic stresses modify friction only under special conditions which usually are not met in lubrication. In addition, the flow rates and the side flow coefficients are calculated. It is shown that the lubricant leakage can be reduced and even avoided when proper measures are taken. For short bearings, diagrams are given for the film extent, the film boundaries, the load carrying capacity, and the attitude of the journal center.

On the study of Rayleigh step slider bearings lubricated with non-Newtonian Rabinowitsch fluid

2017 ◽  
Vol 69 (5) ◽  
pp. 666-672
Author(s):  
N.B. Naduvinamani ◽  
Siddharam Patil ◽  
S.S. Siddapur
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Content Type ◽  
Slider Bearings ◽  
Load Carrying ◽  
Modified Reynolds Equation ◽  
Frictional Coefficients

Purpose Nowadays, the use of Newtonian fluid as a lubricant is diminishing day by day, and the use of non-Newtonian fluids has gained importance. This paper presents an analysis of the static characteristics of Rayleigh step slider bearing lubricated with non-Newtonian Rabinowitsch fluid, which has not been studied so far. The purpose of this paper is to derive the modified Reynolds equation for Rabinowitsch fluids for two regions and to obtain the optimum bearing parameters for the Rayleigh step slider bearings. Design/methodology/approach The governing equations relevant to the problem under consideration are derived. The modified Reynolds equation is derived, and it is found to be highly non-linear and hence small perturbation method is adopted to find solution. Findings From this study it is found that there is an increase in the load-carrying capacity, pressure and frictional coefficients for dilatant fluids as compared to the corresponding Newtonian case. Further, for dilatant lubricants the maximum load-carrying capacity is attained for the slightly larger values of entry region length of Rayleigh step bearing as compared to Newtonian and pseudoplastic lubricants. Originality/value Rabinowitsch fluid is used for the study of lubrication characteristics of Rayleigh step bearings. The author believes that the paper presents these results for the first time.

Sign in / Sign up

Export Citation Format

Share Document