Investigation of the Effects of Initial Fluid Film Profile on Pumping Ring Operation

1983 ◽  
Vol 105 (4) ◽  
pp. 609-614
Author(s):  
P. J. Smith ◽  
T. G. Keith
Keyword(s):  
Pressure Distribution ◽  
Flow Pattern ◽  
Pronounced Effect ◽  
Fluid Film ◽  
Shaft Seal ◽  
Initial Film ◽  
Film Profile

The effect of the initial fluid film profile on the pumping capacity of a pumping ring shaft seal has been investigated numerically. Linear, concave, convex and compound film shapes were considered. It was found that initial film shape has a pronounced effect on both the amount of fluid pumped and on the character of the flow pattern and pressure distribution within the film.

A Study of the Elastohydrodynamic Problem in Rectangular Elastomeric Seals

1984 ◽  
Vol 106 (4) ◽  
pp. 505-512 ◽  
Author(s):  
E. Prati ◽  
A. Strozzi
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Fluid Film ◽  
Hydrodynamic Theory ◽  
Sliding Velocity ◽  
Dry Contact ◽  
Elastomeric Seals ◽  
Film Profile

This paper deals with the study of the elastohydrodynamic lubrication in elastomeric rectangular seals with rounded edges. The photoelastic and the numerical methods are employed in the determination of the dry contact pressure distribution. The existence of two contact pressure peaks near the seal edges is clarified. The influence of the sealed pressure and the sliding velocity on the pressure distribution is examined experimentally. The influence of Poisson’s ratio and constitutive relation on the stress field is studied numerically. The inverse hydrodynamic theory and the numerical method are used in the determination of the fluid film profile. The experimental and numerical fluid film shapes at the inlet are discussed. The influence on the film shape of the sealed pressure is studied experimentally, while the influence of the sliding velocity is examined numerically. The agreement between the experimental and the numerical results for the common cases is satisfactory.

scholarly journals Numerical Simulation of the Hydraulic Performances and Flow Pattern of Swallow-Tailed Flip Bucket

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Lifang Zhang ◽  
Jianmin Zhang ◽  
Yakun Guo ◽  
Yong Peng
Keyword(s):  
Pressure Distribution ◽  
Flow Pattern ◽  
Width Ratio ◽  
Unit Discharge ◽  
Plunge Pool ◽  
Strip Shape ◽  
Pressure Peak ◽  
The Impact ◽  
Discharge Distribution ◽  
Opening Width

In this study, the evolution process of the swallow-tailed flip bucket water nappe entering into the plunge pool is simulated by using the standard k-ε turbulence model and the volume-of-fluid method. The effects of the upstream opening width ratio and downstream bucket angle on the flow pattern, the unit discharge distribution, and the impact pressure distribution are studied. Based on the numerical results, the inner and outer jet trajectories are proposed by using the data. Results show that the longitudinal stretching length decreases with the increase of the upstream opening width ratio and increases with the increase of the downstream bucket angle. The water nappe enters the plunge pool in a long strip shape. Thus, the unit discharge distribution of water nappe entry is consistent with the pressure distribution at the plunge pool bottom. The upstream opening width ratio and downstream bucket angle should be chosen as their intermediate values in order to have a uniform discharge distribution and to reduce the pressure peak at the plunge pool floor, which is effectively to avoid instability and destruction of plunge pool floor.

scholarly journals Effects of Hydrostatic Pocket Shape on the Flow Pattern and Pressure Distribution

1995 ◽  
Vol 1 (3-4) ◽  
pp. 225-235 ◽  
Author(s):  
M. J. Braun ◽  
M. Dzodzo
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Flow Pattern ◽  
Stokes Equations ◽  
The Other ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Hydrostatic Bearing ◽  
Collocated Grid ◽  
Dimensionless Formulation

The flow in a hydrostatic pocket is numerically simulated using a dimensionless formulation of the 2-D Navier-Stokes equations written in primitive variables, for a body fitted coordinates system, and applied through a collocated grid. In essence, we continue the work of Braun et al. 1993a, 1993b] and extend it to the study of the effects of the pocket geometric format on the flow pattern and pressure distribution. The model includes the coupling between the pocket flow and a finite length feedline flow, on one hand, and the pocket and its adjacent lands on the other hand. In this context we shall present, on a comparative basis, the flow and the pressure patterns at the runner surface for square, ramped-Rayleigh step, and arc of circle pockets. Geometrically all pockets have the same footprint, same lands length, and same capillary feedline. The numerical simulation uses the Reynolds number based on the lid(runner) velocity and the inlet jet strengthFas the dynamic similarity parameters. The study aims at establishing criteria for the optimization of the pocket geometry in the larger context of the performance of a hydrostatic bearing.

Effect on the Film Pressure Distribution on a Hydrodynamic Tilting Pad Bearing Caused by the Coating of the Journal With DLC by Triboadhesion

2007 ◽  
Author(s):  
J. M. Rodri´guez-Lelis ◽  
D. Vela-Arvizo ◽  
A. Abundez-Pliego ◽  
S. Reyes-Galindo ◽  
J. Navarro-Torres ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Surface Properties ◽  
Fluid Film ◽  
Maximum Pressure ◽  
Shear Stresses ◽  
Film Pressure ◽  
Surface Energies ◽  
Tilting Pad ◽  
Film Characteristics

This work is concerned with the effect on the film pressure distribution caused on a hydrodynamic tilting pad bearing, by the change in surface properties of the journal. Here two identical journals, both manufactured with AISI 9840, were employed. One of them was coated with DLC by the triboadhesion process, and the second, was used as a reference without applying any coating. During tests, the tilting pad experienced a lower film pressure distribution when the journal coated with DLC was employed. This phenomena could readily be attributed to the different surface energies of the coated and uncoated journals, which in time causes that the fluid film characteristics to be modified by the reduction of the shear stresses at the wall, thus reducing the maximum film pressure measured and shifting the maximum pressure to the line of symmetry, drawn from the center of the journal to the pin of rotation of the tilting pad.

scholarly journals Squeeze Film Dampers Executing Small Amplitude Circular-Centered Orbits in High-Speed Turbomachinery

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Pressure Distribution ◽  
Small Amplitude ◽  
High Speed ◽  
Fluid Film ◽  
Distribution Model ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Squeeze Film Dampers ◽  
Reaction Forces

This work represents a pressure distribution model for finite length squeeze film dampers (SFDs) executing small amplitude circular-centered orbits (CCOs) with application in high-speed turbomachinery design. The proposed pressure distribution model only accounts for unsteady (temporal) inertia terms, since based on order of magnitude analysis, for small amplitude motions of the journal center, the effect of convective inertia is negligible relative to unsteady (temporal) inertia. In this work, the continuity equation and the momentum transport equations for incompressible lubricants are reduced by assuming that the shapes of the fluid velocity profiles are not strongly influenced by the inertia forces, obtaining an extended form of Reynolds equation for the hydrodynamic pressure distribution that accounts for fluid inertia effects. Furthermore, a numerical procedure is represented to discretize the model equations by applying finite difference approximation (FDA) and to numerically determine the pressure distribution and fluid film reaction forces in SFDs with significant accuracy. Finally, the proposed model is incorporated into a simulation model and the results are compared against existing SFD models. Based on the simulation results, the pressure distribution and fluid film reaction forces are significantly influenced by fluid inertia effects even at small and moderate Reynolds numbers.

scholarly journals Foil Bearing Design Guidelines for Improved Stability

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
J. Schiffmann ◽  
Z. S. Spakovszky
Keyword(s):  
Pressure Distribution ◽  
Mass Parameter ◽  
Critical Mass ◽  
Design Guidelines ◽  
Fluid Film ◽  
Structural Damping ◽  
Foil Bearing ◽  
Improved Stability ◽  
Bearing Design ◽  
The Impact

Experimental evidence in the literature suggests that foil bearing-supported rotors can suffer from subsynchronous vibration. While dry friction between top foil and bump foil is thought to provide structural damping, subsynchronous vibration is still an unresolved issue. The current paper aims to shed new light onto this matter and discusses the impact of various design variables on stable foil bearing-supported rotor operation. It is shown that, while a time domain integration of the equations of motion of the rotor coupled with the Reynolds equation for the fluid film is necessary to quantify the evolution of the rotor orbit, the underlying mechanism and the onset speed of instability can be predicted by coupling a reduced order foil bearing model with a rigid-body, linear, rotordynamic model. A sensitivity analysis suggests that structural damping has limited effect on stability. Further, it is shown that the location of the axial feed line of the top foil significantly influences the bearing load capacity and stability. The analysis indicates that the static fluid film pressure distribution governs rotordynamic stability. Therefore, selective shimming is introduced to tailor the unperturbed pressure distribution for improved stability. The required pattern is found via multiobjective optimization using the foil bearing-supported rotor model. A critical mass parameter is introduced as a measure for stability, and a criterion for whirl instability onset is proposed. It is shown that, with an optimally shimmed foil bearing, the critical mass parameter can be improved by more than two orders of magnitude. The optimum shim patterns are summarized for a variety of foil bearing geometries with different L/D ratios and different degrees of foil compliance in a first attempt to establish more general guidelines for stable foil bearing design. At low compressibility (Λ < 2), the optimum shim patterns vary little with bearing geometry; thus, a generalized shim pattern is proposed for low compressibility numbers.

A Numerical Analysis for the Transient EHL Process of a Cam-Tappet Pair in I. C. Engine

1989 ◽  
Vol 111 (3) ◽  
pp. 413-417 ◽  
Author(s):  
Xiaolan Ai ◽  
Haiqing Yu
Keyword(s):  
Numerical Analysis ◽  
Pressure Distribution ◽  
Numerical Method ◽  
Rotation Angle ◽  
Elastohydrodynamic Lubrication ◽  
Surface Failure ◽  
Lubrication Conditions ◽  
Film Profile

The transient elastohydrodynamic lubrication (EHL) process of cam-tappet pair in I. C. engine is analyzed with a full numerical method. The variations of pressure distribution and film profile as a function of rotation angle of cam shaft provide useful information in evaluating lubrication conditions as well as analyzing failures of contacting surfaces. Results show that the segment in cam contour from φ = 30 to φ = 110 deg is a difficult lubrication range, and surface failure may occur first in this range. This statement was confirmed by preliminary exprimental work conducted in a testing rig.

Analysis on the steady state performance of a multi pad externally adjustable fluid film bearing

2019 ◽  
Vol 71 (6) ◽  
pp. 803-809 ◽  
Author(s):  
Girish Hariharan ◽  
Raghuvir Pai
Keyword(s):  
Steady State ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Fluid Film ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Content Type ◽  
Bearing Load ◽  
Performance Capability ◽  
Film Profile

Purpose This study aims to investigate the performance characteristics of an externally adjustable bearing with multiple pads in steady state conditions. The proposed adjustable bearing geometry can effectively control the hydrodynamic operation in bearing clearances by adjusting the pads in radial and tilt directions. These pad adjustments have a significant role in improving the bearing characteristics such as load capacity, attitude angle, side leakage, friction variable and Sommerfeld number, which will be analysed in this paper. Design/methodology/approach The adjustable bearing is designed with circumferentially spaced four bearing pads subjected to similar radial and tilt adjustments. Tilt angles are applied along the leading edges of bearing pads. A modified film thickness equation is used to incorporate the pad adjustments and accurately predict the variation in film profile. Finite difference approximation is adopted to solve the Reynolds equation and discretize the fluid film domain. Findings For negative radial and tilt adjustments, higher hydrodynamic pressures are generated in bearing clearances, which increases the bearing load capacity at different eccentricity ratios. From comparative analysis for different pad adjustments, superior bearing performance is observed for bearing pads under negative radial and negative tilt adjustments. Originality/value This research presents a detailed theoretical approach to analyse the performance capability of a four pad adjustable bearing geometry, which is not available in literatures. Improved bearing performances with negative pad adjustments can attract bearing designers to implement the proposed adjustability-bearing concept in rotating machineries.

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