scholarly journals Ferrofluid lubrication of a parallel plate squeeze film bearing

2003 ◽  
pp. 221-240 ◽  
Author(s):  
Rajesh Shah ◽  
M.V. Bhat
Keyword(s):  
Response Time ◽  
Parallel Plate ◽  
Load Capacity ◽  
Type Equation ◽  
Material Constant ◽  
Porous Matrix ◽  
Squeeze Film ◽  
Graphical Form ◽  
Anisotropic Permeability ◽  
Effects Of Rotation

We derived a Reynolds type equation for a ferrofluid lubrication in a squeeze film between two circular plates using Jenkins model and considering combined effects of rotation of the plates, anisotropic permeability in the porous matrix and slip velocity at the interface of porous matrix and film region. We used it to study the case of a parallel-plate squeeze film bearing. Expressions were obtained for dimensionless pressure, load capacity and response time. Computed values were displayed some in tabular form and some in graphical form. The load capacity decreased with increasing values of the radial permeability and attained a minimum when the plates rotated in the opposite directions with nearly the same speed. It increased with increasing values of the axial permeability or material constant of Jenkins model and attained a maximum when the value of the material constant was near unity. It increased or decreased for increasing values of the speed of rotation of the upper plate according as the value of the material constant is zero or not. The response time slowly decreased with increasing values of the radial permeability, speed of rotation of upper plate or the material constant. But, it increased with increasing values of the axial permeability and attained a maximum when the plates rotated in opposite directions with nearly the same speed. Anisotropic permeability affected the bearing characteristics considerably.

Effects of Surface Roughness and Non-Newtonian Micropolar Fluid Squeeze Film between Conical Bearings

2017 ◽  
Vol 72 (12) ◽  
pp. 1151-1158 ◽  
Author(s):  
P. S. Rao ◽  
Birendra Murmu ◽  
Santosh Agarwal
Keyword(s):  
Surface Roughness ◽  
Response Time ◽  
Micropolar Fluid ◽  
Load Capacity ◽  
Squeeze Film ◽  
Graphical Form ◽  
Load Carrying ◽  
Transverse Roughness ◽  
Improved Performance ◽  
Bearing System

AbstractBased on the micropolar fluid models of Eringen and Christensen’s stochastic theories, the analysis of the effects of surface roughness and the squeeze film lubrication problems between conical bearings are presented. The concerned nondimensional Reynolds equation is solved with appropriate boundary conditions in dimensionless form to find the pressure distribution, which is then used to obtain the expression for load-carrying capacity, paving the way for the calculation of response time. Computed values of pressure, load capacity, and response time are displayed in graphical form. This investigation reveals that the bearing system admits an improved performance as compared with that of a bearing system working with a conventional lubricant. According to the results, the effects of transverse roughness provide an increase in the bearing characteristics as compared with the smooth bearing lubricated with micropolar fluid whereas the influences of longitudinal roughness yield a reversed trend. The quantifiable effects of rough surfaces and non-Newtonian fluids on bearing performances are more pronounced for the roughness and micropolar parameters.

Effect of non-Newtonian lubrication of squeeze film conical bearing with the porous wall operating with Rabinowitsch fluid model

2018 ◽  
Vol 232 (10) ◽  
pp. 1293-1303 ◽  
Author(s):  
PS Rao ◽  
AK Rahul ◽  
S Agarwal
Keyword(s):  
Response Time ◽  
Reynolds Equation ◽  
Graphical Representation ◽  
Load Capacity ◽  
Porous Wall ◽  
Squeeze Film ◽  
Film Pressure ◽  
Pressure Load ◽  
Conical Bearing ◽  
Modified Reynolds Equation

In this article, a theoretical study is made to explore the effect of squeezing film in conical bearing for the permeable porous wall utilizing non-Newtonian lubricants. The Permeable medium impacts are characterized by modified Darcy’s law. The modified Reynolds equation representing the non-Newtonian properties following the cubic stress law condition is determined. After general contemplations on the flow in a bearing clearance and in a porous wall, the Cameron approximation is used to acquire modified Reynolds equation. The perturbation technique is used to solve the modified Reynolds equation and closed-form expressions are obtained for the fluid film pressure, load capacity, and response time. The results are illustrated by the graphical representation which shows that the introduction of porous on conical bearing with Rabinowitsch fluid, dilatant lubricant increases the film pressure, load capacity, and response time and decrease for pseudoplastic lubricant as compared to Newtonian fluid.

scholarly journals A Study of Hydromagnetic Longitudinal Rough Circular Step Bearing

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Jatinkumar V. Adeshara ◽  
M. B. Prajapati ◽  
G. M. Deheri ◽  
R. M. Patel
Keyword(s):  
Standard Deviation ◽  
Type Equation ◽  
Squeeze Film ◽  
Graphical Form ◽  
Load Bearing Capacity ◽  
Random Roughness ◽  
Supply Pressure ◽  
Longitudinal Roughness ◽  
Negative Effect ◽  
Bearing System

This article discusses the effect of longitudinal roughness on the performance of hydromagnetic squeeze film in circular step bearing. To characterize the random roughness of the bearing surfaces the stochastic model of Christensen and Tonder has been employed. The stochastically averaged Reynolds’ type equation is solved using suitable boundary conditions to obtain the pressure distribution and then the load bearing capacity is computed. The results are presented in graphical form. The graphical results presented here establish that the hydromagnetic lubrication offers significant help to the longitudinal roughness pattern to enhance the performance of the bearing system. Of course, conductivities of the plates, standard deviation, and the supply pressure contribute towards reducing the negative effect induced by variance (+ve) and skewness (+ve).

Derivation of Non-Newtonian Magnetic Fluid Lubricated Rough Centrosymmetric Squeeze Film Reynolds Equation and its Application

2017 ◽  
Vol 35 (1) ◽  
pp. 113-119
Author(s):  
J. R. Lin ◽  
L. M. Chu ◽  
H. L. Chiang ◽  
Y. K. Chiu
Keyword(s):  
Magnetic Fields ◽  
Magnetic Fluid ◽  
Reynolds Equation ◽  
Fluid Model ◽  
Load Capacity ◽  
Magnetic Fluids ◽  
Squeeze Film ◽  
Rotational Inertia ◽  
Effects Of Rotation ◽  
Circular Disks

AbstractBased upon the Shliomis ferromagnetic fluid model and the Stokes microcontinuum theory incorporating with the Christensen stochastic model, a modified Reynolds equation of centrosymmetric squeeze films has been derived in this paper. The Reynolds equation includes the combined effects of non-Newtonian rheology, magnetic fluids with applied magnetic fields, rotational inertia forces, and surface roughness. To guide the use of the derived equation, the squeeze film of rotational rough-surface circular disks lubricated with non-Newtonian magnetic fluids is illustrated. According to the results obtained, the effects of rotation inertia decrease the load capacity and the squeeze film time of smooth circular disks. By the use of non-Newtonian magnetic fluids with applied magnetic fields, the rotational circular disks predict better squeeze film performances. When the influences of circumferential roughness patterns are considered, the non-Newtonian magnetic-fluid lubricated rotational rough disks with applied magnetic fields provide further higher values of the load capacity and the squeeze film time as compared to those of the smooth case.

Influence of different flow regimes on the performance characteristics of a four-pad hydrostatic squeeze film damper loaded between pads

2019 ◽  
Vol 71 (3) ◽  
pp. 440-446
Author(s):  
Amina Nemchi ◽  
Ahmed Bouzidane ◽  
Aboubakeur Benariba ◽  
Hicham Aboshighiba
Keyword(s):  
Turbulent Flow ◽  
Load Capacity ◽  
Flow Regimes ◽  
Performance Characteristics ◽  
Squeeze Film ◽  
Eccentricity Ratio ◽  
Flow Conditions ◽  
Content Type ◽  
Turbulent Flow Regime ◽  
Squeeze Film Dampers

Purpose The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between pads. Design/methodology/approach A numerical model based on Constantinescu’s turbulent lubrication theory using the finite difference method has been developed and presented to study the effect of eccentricity ratio on the performance characteristics of four-pad hydrostatic SFDs under different flow regimes. Findings It was found that the influence of turbulent flow on the dimensionless damping of four-pad hydrostatic SFDs appears to be essentially controlled by the eccentricity ratio. It was also found that the laminar flow presents higher values of load capacity compared to bearings operating under turbulent flow conditions. Originality/value In fact, the results obtained show that the journal bearing performances are significantly influenced by the turbulent flow regime. The study is expected to be useful to bearing designers.

Pressure generation in rough conical bearing using non-Newtonian Rabinowitsch fluid with variable viscosity

2019 ◽  
Vol 71 (3) ◽  
pp. 357-365 ◽  
Author(s):  
Pentyala Srinivasa Rao ◽  
Amit Kumar Rahul
Keyword(s):  
Surface Roughness ◽  
Response Time ◽  
Fluid Model ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Pressure Load ◽  
Load Carrying ◽  
Conical Bearing ◽  
Viscosity Variation

Purpose This paper aims to investigate the effect of surface roughness (radial and azimuthal) and viscosity variation on a squeeze film of a conical bearing with a non-Newtonian lubricant by using Rabinowitsch fluid model. Design/methodology/approach The main objective is to determine the stochastic nonlinear modified Reynolds equation for rough conical bearing. Later, first-order closed-form solutions are obtained using a small perturbation method and are numerically solved using the Gauss quadrature method. Findings The findings of this paper, numerical calculations, are analyzed for pressure, load carrying capacity and response time. The simulated results indicate that the influence of surface roughness increases the pressure, load carrying capacity and response time, whereas the viscosity variation factor decreases the pressure, load and response time. Originality/value According to both types of surface roughness with viscosity variation, the performance of a squeeze film rough conical bearing was improved by using Rabinowitsch fluid model. As it is inevitable to consider viscosity variation for bearing designer, it leads to a long life period of conical bearing.

Dynamic Behavior of Pure Squeeze Films in Narrow Porous Bearings

1974 ◽  
Vol 96 (3) ◽  
pp. 361-364 ◽  
Author(s):  
P. R. K. Murti
Keyword(s):  
Dynamic Behavior ◽  
Cyclic Load ◽  
Journal Bearing ◽  
Load Capacity ◽  
Squeeze Film ◽  
Closed Form Expression ◽  
Cyclic Loads ◽  
Eccentricity Ratio ◽  
Form Expression ◽  
Bearing Material

The dynamic behavior of squeeze film in a narrow porous journal bearing under a cyclic load is analyzed. A thin-walled bearing with a nonrotating journal is considered and a closed form expression for the pressure distribution is derived. The locus of the journal center is found by numerical methods and it is established with an example that actual contact between the journal and bearing can be avoided by appropriate design of the bearing. Consequently, it is proved that pure squeeze films have a load capacity only under cyclic loads. The analysis also reveals that the permeability of the bearing material and the wall thickness of the bearing influence significantly the operating eccentricity ratio.

Experimental Verification of Rarefied Gas Squeezed-Film Damping Models Used in MEMS

2006 ◽  
Author(s):  
Lukas Mol ◽  
Luis A. Rocha ◽  
Edmond Cretu ◽  
Reinoud F. Wolffenbuttel
Keyword(s):  
Experimental Verification ◽  
Parallel Plate ◽  
Rarefied Gas ◽  
Experimental Results ◽  
Squeeze Film ◽  
Border Effects ◽  
Knudsen Numbers ◽  
Electrostatic Mems ◽  
Simulation Errors

Existing compact parallel-plate squeeze-film models including rarefaction and border effects are verified using the experimental results of a new electrostatic MEMS actuation technique that enables full gap positioning. Measurements at high Knudsen numbers ranging from 0.03 to 0.18 are performed and results compared to the models. The simulation errors are confirmed to be lower than 20%. The experiments also indicate that both gas rarefaction and border effects have to be included in any model.

An Investigation Into the Influence of Fluid Viscoelasticity in a Squeeze Film Bearing

1978 ◽  
Vol 100 (1) ◽  
pp. 56-64 ◽  
Author(s):  
John A. Tichy ◽  
Ward O. Winer
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
High Molecular Weight ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Surface Film ◽  
Free Fall ◽  
Squeeze Film ◽  
Delayed Response ◽  
High Molecular Weight Polymers

This investigation concerns a prediction of the behavior of viscoelastic fluids in a parallel circular squeeze film with a constant approach velocity, and a comparison to experimental results. The squeeze film geometry has direct application to unsteady hydrodynamic lubrication. The analysis predicts that load capacity of a viscoelastic fluid may be increased due to normal stress effects or decreased due to a delayed response of shear stress to a change in shear rate. Ten tested fluids include Newtonian control fluids, silicone fluids, high molecular weight polymers in petroleum oils, and extremely high molecular weight polymers in water and glycerin. The experimental squeezing is accomplished by the free fall of a cylindrical steel rod along its axis toward a stationary opposing surface. Film thickness, velocity of approach and load are measured. The velocity of approach is essentially constant in the range of film thickness considered. The water-glycerin-polymer solutions exhibited load capacity increases up to 33 percent, while the petroleum-polymer and silicone fluids showed decreases to 23 percent. It appears that viscoelastic effects cannot account for the reported improved bearing performance of polymer-additive lubricants.

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