Fluid Inertia Effects on the Load Capacity of Spherical Spiral Groove Bearings

1986 ◽  
Vol 108 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Yuichi Sato
Keyword(s):  
Incompressible Fluid ◽  
Centrifugal Force ◽  
Load Capacity ◽  
Inertia Force ◽  
Laminar Regime ◽  
Fluid Inertia ◽  
Spiral Groove ◽  
Centrifugal Effect ◽  
Inertia Effects ◽  
Theoretical Results

The effects of centrifugal force on the load capacity of inwardly and outwardly spherical spiral groove bearings, operated in laminar regime and lubricated with incompressible fluid, have been investigated. The narrow groove theory has been generalized to include the centrifugal effect of lubricant. The analysis demonstrates that the fluid inertia force reduces the load capacity of an inwardly pumping bearing, whereas it increases the load capacity of an outwardly pumping bearing. The theoretical results are compared with the experimental ones.

Extended Finite Element Analysis of Journal Bearing Dynamic Forced Performance to Include Fluid Inertia Force Coefficients

2012 ◽  
Author(s):  
Luis San Andrés
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Small Amplitude ◽  
Forced Response ◽  
Inertia Force ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Force Coefficients ◽  
Reaction Forces ◽  
Bearing Stiffness

Reynolds equation governs the generation of hydrodynamic pressure in oil lubricated fluid film bearings. The static and dynamic forced response of a bearing is obtained from integration of the film pressure on the bearing surface. For small amplitude journal motions, a linear analysis represents the fluid film bearing reaction forces as proportional to the journal center displacements and velocity components through four stiffness and four damping coefficients. These force coefficients are integrated into rotor-bearing system structural analysis for prediction of the system stability and the synchronous response to imbalance. Fluid inertia force coefficients, those relating reaction forces to journal center accelerations, are routinely ignored because most oil lubricated bearings operate at relatively low Reynolds numbers, i.e., under slow flow conditions. Modern rotating machinery operates at ever increasing surface speeds to deliver more power in smaller size units. Under these operating conditions fluid inertia effects need to be accounted for in the forced response of oil lubricated bearings, as recent experimental test data also reveal. The paper presents a finite element formulation to predict added mass coefficients in oil lubricated bearings by extending a basic formulation that already calculates the bearing stiffness and damping force coefficients. That is, a small amplitude perturbation analysis of the lubrication flow equations keeps the temporal fluid inertia effects and develops a set of equations to obtain the bearing stiffness, damping and inertia force coefficients. The method does not impose on the cost of the original formulation which makes it very attractive for ready implementation in existing software. Predictions of the computational model are benchmarked against archival test data for an oil-lubricated pressure dam bearing supporting large compressors. The comparisons show fluid inertia effects cannot be ignored for operation at high rotor speeds and with small static loads.

A simple expression for fluid inertia force acting on micro-plates undergoing squeeze film damping

2010 ◽  
Vol 467 (2126) ◽  
pp. 522-536 ◽  
Author(s):  
Shujuan Huang ◽  
Diana-Andra Borca-Tasciuc ◽  
John A. Tichy
Keyword(s):  
Separation Distance ◽  
Simple Expression ◽  
Squeeze Film ◽  
Inertia Force ◽  
Viscous Damping ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Viscous Forces ◽  
Squeeze Film Damping ◽  
Micro Plates

Squeeze film damping in systems employing micro-plates parallel to a substrate and undergoing small normal vibrations is theoretically investigated. In high-density fluids, inertia forces may play a significant role affecting the dynamic response of such systems. Previous models of squeeze film damping taking inertia into account do not clearly isolate this effect from viscous damping. Therefore, currently, there is no simple way to distinguish between these two hydrodynamic effects. This paper presents a simple solution for the hydrodynamic force acting on a plate vibrating in an incompressible fluid, with distinctive terms describing inertia and viscous damping. Similar to the damping constant describing viscous losses, an inertia constant, given by ρL 3 W / h (where ρ is fluid density, L and W are plate length and width, respectively, and h is separation distance), may be used to accurately calculate fluid inertia for small oscillation Reynolds numbers. In contrast with viscous forces that suppress the amplitude of the oscillation, it is found that fluid inertia acts as an added mass, shifting the natural frequency of the system to a lower range while having little effect on the amplitude. Dimensionless parameters describing the relative importance of viscous and inertia effects also emerge from the analysis.

Paper 5: The Hydrosphere

1967 ◽  
Vol 182 (14) ◽  
pp. 33-40
Author(s):  
D. Dowson ◽  
C. M. Taylor
Keyword(s):  
Bearing Capacity ◽  
Recent Work ◽  
Load Capacity ◽  
Thermal Distortion ◽  
Approximate Analysis ◽  
Fluid Inertia ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Inertia Effects ◽  
Preliminary Examination

A preliminary examination of the bearing indicates that it is not capable of hydrodynamic action as the fluid film is parallel in the direction of motion. However, in practice it has been found that the bearing can support considerable loads. Earlier papers by the authors have examined the proposal of Shaw and Strang that the inertia of the lubricant could account for the load capacity of the bearing. This contention was rejected by the authors, and after other possible explanations had been investigated it was concluded that thermal distortion was the most likely cause of the load-bearing capacity. In this paper recent work will be reported which supports this proposal. The analysis of fluid inertia effects is summarized for a continuous hemispherical seat whose surface is disturbed only by the central lubricant supply hole (the grooveless case). The paper also presents experimental results and an approximate analysis of the thermal distortion for a hydrosphere seat with four lubricant grooves running from the supply hole to the equator along longitudinal lines.

Theoretical Investigation of Fluid Inertia Effects and Stability of Self-Acting Gas Journal Bearings

1999 ◽  
Vol 121 (4) ◽  
pp. 836-843 ◽  
Author(s):  
G. Belforte ◽  
T. Raparelli ◽  
V. Viktorov
Keyword(s):  
Reynolds Equation ◽  
Equation Of Motion ◽  
Journal Bearings ◽  
Fluid Inertia ◽  
Stability Parameters ◽  
Inertia Effects ◽  
Stability Diagrams ◽  
Intensive Use ◽  
Stability Limits ◽  
Theoretical Results

The journal equation of motion and the complete Reynolds equation of compressible fluid film are numerically solved and a computer program is developed. The formulas are for externally pressurized bearings, but results are shown only for self-acting bearings. For certain cases, the validity of the theoretical results is verified by comparison with the experimental data available from the literature. Through intensive use of the program, journal center trajectories are obtained and effects of fluid inertia are investigated. New stability parameters are presented and stability diagrams are established for bearings with L/D = 0.25, 0.5, 1, 1.5, and 2. The rotor unbalance effects on bearing stability limits are illustrated for several cases.

Turbulent Hybrid Bearings With Fluid Inertia Effects

1990 ◽  
Vol 112 (4) ◽  
pp. 699-707 ◽  
Author(s):  
Luis San Andre´s
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Pressure Rise ◽  
Reynolds Numbers ◽  
Dynamic Force ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Friction Factors ◽  
Region Flow ◽  
The Stability

High speed hybrid bearings for cryogenic applications demand large levels of external pressurization to provide substantial load capacity. These conditions give rise to large film Reynolds numbers, and thus, cause the fluid flow within the bearing film to be turbulent and dominated by fluid inertia effects both at the recess edges and at the thin film lands. The analysis includes the effect of recess fluid compressibility and a model for the pressure rise within the recess region. Flow turbulence is simulated by friction factors dependent on the local Reynolds numbers and surface conditions. A perturbation method is used to calculate the zeroth and first flow fields and determine the bearing steady-state and dynamic force response. Comparison of results with existing experimental data shows the accuracy of the present full inertial-turbulent analysis. A roughened bearing surface is shown to improve considerably the stability characteristics of hybrid bearings operating at high speeds.

The Effect of Fluid Inertia on a Porous Thrust Plate—An Analytical Solution

1971 ◽  
Vol 93 (1) ◽  
pp. 202-206 ◽  
Author(s):  
F. C. Hsing
Keyword(s):  
Boundary Layer ◽  
Analytical Solution ◽  
Load Capacity ◽  
Numerical Data ◽  
Analytic Model ◽  
Inertia Effect ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Narrow Region ◽  
Gas Bearing

A theoretical analysis was made to study the effect of fluid inertia on a porous thrust plate. The most elementary configuration was chosen as an analytic model to investigate this effect with a minimum of mathematical complexities. Numerical data were obtained for an incompressible film. The results reveal that the effect of fluid inertia can be important, depending on the film thickness H and a parameter Ω. For small value of H the inertia effect is essentially confined to a very narrow region near the edge of the bearing while for large values of H this effect spreads throughout the fluid film. This pressure boundary layer at low H is similar to that in a self-acting gas bearing. In general it was found that inertia effects tend to influence favorably the flow and load capacity of porous thrust plates.

Fluid Inertia Effects in Non-Newtonian Squeeze Films

1976 ◽  
Vol 98 (3) ◽  
pp. 409-411 ◽  
Author(s):  
A. F. Elkouh
Keyword(s):  
Load Capacity ◽  
Squeeze Film ◽  
Energy Integral ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
First Order ◽  
Integral Methods ◽  
Method Yield ◽  
Pseudoplastic Fluids ◽  
Good Agreement

The momentum and energy integral methods are used to study the effect of inertia on the behavior of a non-Newtonian (Power Law) squeeze film. It is shown that the inertia correction in the load capacity is more significant for pseudoplastic fluids, n < 1. For a Newtonian fluid, n = 1, the expressions obtained by using the energy integral method yield results identical to those obtained from a first-order iteration, and which are in good agreement with available experiments.

Fluid Inertia Effects in a Squeeze Film Between Two Plane Annuli

1984 ◽  
Vol 106 (2) ◽  
pp. 223-227 ◽  
Author(s):  
A. F. Elkouh
Keyword(s):  
Power Series ◽  
Load Capacity ◽  
Equations Of Motion ◽  
Squeeze Film ◽  
Squeezing Flow ◽  
Series Expansions ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Flow Parameters ◽  
Power Series Expansions

An analysis is presented for the laminar squeezing flow of a Newtonian in-compressible fluid between parallel plane annuli. Both local and convective inertia of the flow are considered in the analysis. Power series expansions in terms of pertinent flow parameters are used to obtain a solution of the equations of motion. Expressions for the pressure and load capacity are presented, and compared with those based on the assumption of inertialess flow.

Effects of fluid inertia forces in ferrofluid lubricated circular stepped squeeze films – Shliomis model

2016 ◽  
Vol 68 (6) ◽  
pp. 712-717 ◽  
Author(s):  
Jaw-Ren Lin ◽  
Tzu-Chen Hung ◽  
Shu-Ting Hu
Keyword(s):  
Load Capacity ◽  
Squeeze Film ◽  
Inertia Force ◽  
Fluid Inertia ◽  
Content Type ◽  
Inertia Parameter ◽  
Machine Systems ◽  
Momentum Integral ◽  
Film Characteristics ◽  
Inertia Forces

Purpose This paper aims to study the inertia squeeze film characteristics between ferrofluid-lubricated circular stepped disks. Owing to the development of modern machine systems, the application of ferrofluids has received great attention. Because the circular disks are a special situation of circular stepped squeeze films, a further study of fluid inertia force effects on the ferrofluid-lubricated circular stepped squeezing mechanism is motivated. Design/methodology/approach On the basis of the ferrohydrodynamic flow model of Shliomis incorporating the momentum integral method, the effects of fluid inertia forces in ferrofluid-lubricated circular stepped squeeze films in the presence of external magnetic fields are investigated in this study. Analytical solutions of squeeze film performances are derived. Findings The fluid inertia force effects provide an increased load capacity and a longer squeeze film time for the ferrofluid-lubricated circular stepped squeeze film, especially for a larger value of the inertia parameter, the Langevin parameter and the volume concentration and a smaller value of the radius ratio and the step height ratio. Originality/value For engineering applications, numerical tables for squeeze film loads of circular stepped disks are also provided in this paper.

Non-Newtonian Inertia Squeeze Film Characteristics in Rectangular Stepped Plates

2015 ◽  
Vol 775 ◽  
pp. 73-77
Author(s):  
Jaw Ren Lin ◽  
Shu Ting Hu
Keyword(s):  
Normal Load ◽  
Load Capacity ◽  
Continuum Theory ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Lubrication Equation ◽  
Momentum Integral ◽  
Film Characteristics ◽  
Inertia Forces

A study of non-Newtonian inertia squeeze film in rectangular stepped plates has been presented in this paper. Applying the momentum integral method incorporating the micro-continuum theory of non-Newtonian fluids, a non-Newtonian inertia lubrication equation is derived. It is found that the fluid inertia effects yield in a higher normal load capacity as well as a longer squeeze film time as compared to the non-Newtonian stepped squeeze film in the absence of fluid inertia forces.

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