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.

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.

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.

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.

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.

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.

Foil Gas Bearing With Compression Springs: Analyses and Experiments

2007 ◽  
Vol 129 (3) ◽  
pp. 628-639 ◽  
Author(s):  
Ju-ho Song ◽  
Daejong Kim
Keyword(s):  
Loss Factor ◽  
Load Capacity ◽  
Underlying Structure ◽  
Equivalent Viscous Damping ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Different Types ◽  
Structural Loss ◽  
Compression Springs ◽  
Gas Bearing

A new foil gas bearing with spring bumps was constructed, analyzed, and tested. The new foil gas bearing uses a series of compression springs as compliant underlying structures instead of corrugated bump foils. Experiments on the stiffness of the spring bumps show an excellent agreement with an analytical model developed for the spring bumps. Load capacity, structural stiffness, and equivalent viscous damping (and structural loss factor) were measured to demonstrate the feasibility of the new foil bearing. Orbit and coast-down simulations using the calculated stiffness and measured structural loss factor indicate that the damping of underlying structure can suppress the maximum peak at the critical speed very effectively but not the onset of hydrodynamic rotor-bearing instability. However, the damping plays an important role in suppressing the subsynchronous vibrations under limit cycles. The observation is believed to be true with any air foil bearings with different types of elastic foundations.

Dynamic Characterization of an Integral Squeeze Film Bearing Support Damper for a Supercritical CO2 Expander

2017 ◽  
Author(s):  
Bugra Ertas ◽  
Adolfo Delgado ◽  
Jeffrey Moore
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Mechanical Impedance ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Damping Behavior ◽  
Impedance Testing ◽  
Stiffness And Damping ◽  
Onset Of Cavitation

The present work advances experimental results and analytical predictions on the dynamic performance of an integral squeeze film damper (ISFD) for application in a high-speed super-critical CO2 (sCO2) expander. The test campaign focused on conducting controlled orbital motion mechanical impedance testing aimed at extracting stiffness and damping coefficients for varying end seal clearances, excitation frequencies, and vibration amplitudes. In addition to the measurement of stiffness and damping; the testing revealed the onset of cavitation for the ISFD. Results show damping behavior that is constant with vibratory velocity for each end seal clearance case until the onset of cavitation/air ingestion, while the direct stiffness measurement was shown to be linear. Measurable added inertia coefficients were also identified. The predictive model uses an isothermal finite element method to solve for dynamic pressures for an incompressible fluid using a modified Reynolds equation accounting for fluid inertia effects. The predictions revealed good correlation for experimentally measured direct damping, but resulted in grossly overpredicted inertia coefficients when compared to experiments.

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