The Eccentric Face Seal with A Tangentially Varying Film Thickness

1969 ◽  
Vol 91 (4) ◽  
pp. 748-755 ◽  
Author(s):  
H. J. Sneck
Keyword(s):  
Film Thickness ◽  
Phase Angle ◽  
Leakage Flow ◽  
Face Seal ◽  
Surface Waviness ◽  
Total Leakage

It is shown analytically that face seal eccentricity combined with surface waviness can contribute an inward or outward leakage component to the total leakage flow depending on the phase angle between the eccentricity and the waviness.

The Misaligned, Eccentric Face Seal

1969 ◽  
Vol 91 (4) ◽  
pp. 695-703 ◽  
Author(s):  
H. J. Sneck
Keyword(s):  
Phase Angle ◽  
Analytical Investigation ◽  
Face Seal ◽  
Total Leakage

The analytical investigation of a misaligned face seal shows that eccentricity will cause a component of the total leakage to be inward or outward depending on the phase angle between the eccentricity and the misalignment.

Influence of Surface Waviness on the Thermal Elastohydrodynamic Lubrication of an Eccentric-Tappet Pair

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Wang ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Surface Waviness ◽  
Film Pressure ◽  
Oil Film ◽  
Working Cycle ◽  
Temperature Oscillations ◽  
Minimum Film Thickness ◽  
Traction Coefficient ◽  
Oil Film Pressure

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense.

On Extending the Narrow Spiral-Groove Theory to Configurations of Interest in Seals

1992 ◽  
Vol 114 (3) ◽  
pp. 563-566 ◽  
Author(s):  
V. N. Constantinescu ◽  
S. Galetuse
Keyword(s):  
Film Thickness ◽  
Length Ratio ◽  
Leakage Flow ◽  
Spiral Groove ◽  
Seal Design ◽  
Variable Angle

The existing narrow-groove theory is used for evaluating leakage flow for various configurations which might be of interest in seal design, including variable angle, film thickness and groove/ridge length ratio.

Hydrodynamic Lubrication and Wear in Wavy Contacting Face Seals

1978 ◽  
Vol 100 (1) ◽  
pp. 81-90 ◽  
Author(s):  
A. O. Lebeck ◽  
J. L. Teale ◽  
R. E. Pierce
Keyword(s):  
Surface Roughness ◽  
Hydrodynamic Lubrication ◽  
Surface Profile ◽  
Operating Conditions ◽  
Face Seal ◽  
Hydrodynamic Load ◽  
Surface Waviness ◽  
Wear Rates ◽  
Elastic Deflection ◽  
Face Seals

A model of face seal lubrication is proposed and developed. Hydrodynamic lubrication for rough surfaces, surface waviness, asperity load support, elastic deflection, and wear are considered in the model. Predictions of the ratio of hydrodynamic load support to asperity load support are made for a face seal sealing a low viscosity liquid where some contact does occur and surface roughness is important. The hydrodynamic lubrication is caused by circumferential surface waviness on the seal faces. Waviness is caused by initial out of flatness or any of the various distortions that occur on seal ring faces in operation. The equilibrium solution to the problem yields one dimensional hydrodynamic and asperity pressure distributions, mean film thickness, elastic deflection, and friction for a given load on the seal faces. The solution is found numerically. It is shown that the fraction of hydrodynamic load support depends on many parameters including the waviness amplitude, number of waves around the seal, face width, ring stiffness, and most importantly, surface roughness. For the particular seal examined the fraction of load support would be small for the amount of waviness expected in this seal. However, if the surface roughness were lower, almost complete lift-off is possible. The results of the analysis show why the initial friction and wear rates in mechanical face seals may vary widely; the fraction of hydrodynamic load support depends on the roughness and waviness which are not necessarily controlled. Finally, it is shown how such initial waviness effects disappear as the surface profile is altered by wear. This may take a long or short time, depending on the initial amount of hydrodynamic load support, but unless complete liftoff is achieved under all operating conditions, the effects of initial waviness will vanish in time for steady state conditions. Practical implications are drawn for selecting some seal parameters to enhance initial hydrodynamic load support without causing significant leakage.

Influence of lubrication starvation and surface waviness on the oil film stiffness of elastohydrodynamic lubrication line contact

2016 ◽  
Vol 24 (5) ◽  
pp. 924-936 ◽  
Author(s):  
Yuanyuan Zhang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Chaosheng Song ◽  
Zufeng Li
Keyword(s):  
Film Thickness ◽  
Contact Stiffness ◽  
Elastohydrodynamic Lubrication ◽  
Force Balance ◽  
Line Contact ◽  
Surface Waviness ◽  
Regular Surface ◽  
Normal Contact ◽  
Oil Film ◽  
Film Stiffness

Stiffness properties of interfacial engineering surfaces are of great importance to the dynamic performance of relevant mechanical systems. Normal contact stiffness and oil film stiffness of line contact problems are studied in this work analytically and numerically. The Hertzian contact theory and the Yang–Sun method are applied to predict the contact stiffness, while the empirical elastohydrodynamic lubrication (EHL) film thickness method and the complete numerical EHL model are used to predict the oil film stiffness. The numerical model mainly consists of the Reynolds equation; the film thickness equation, in which the regular surface roughness is taken into consideration; the force balance equation; and the viscosity-pressure equation. The effects of the normal load, rolling speed, regular surface waviness, and starved lubrication level on the oil film stiffness are investigated.

scholarly journals Hub clearance effect in the design space of the cantilevered stator embedded in a 4-stage low-speed research compressor

2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110371
Author(s):  
Zhenzhou Ju ◽  
Jinfang Teng ◽  
Yuchen Ma ◽  
Mingmin Zhu ◽  
Xiaoqing Qiang
Keyword(s):  
Design Space ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Blade Loading ◽  
Low Speed ◽  
Entropy Variation ◽  
Total Leakage ◽  
Stage Matching ◽  
The Relationship

This paper focuses on the effect of hub clearance in the design space of the highly loaded cantilevered stator. The embedded 1.5 stages of a low-speed research compressor (LSRC) were conducted with Unsteady Reynolds Average Navier-Stokes (URANS) numerical investigation, and the cantilevered stator adopts positive bowed and fore-sweep three-dimensional design. The research details that with the hub clearance increasing from 1.1% to 4.5% span, the loss coefficient and the total leakage momentum of the cantilevered stator correspond to the change of the blade loading near the hub. When designing the inlet metal angle of the rotor downstream the cantilevered stator, emphasis should be given to considering the inter-stage matching below 15% span. The mixing of leakage flow in 1.1% span clearance and 2.5% span clearance is basically completed in the S3 passage, but the mixing of leakage flow in 3.5% span clearance and 4.5% span clearance is still relatively strong downstream of S3. When calculating the relative entropy variation based on Denton’s mixing model, attention should be paid to the relationship between the leakage flow velocity affected by the hub gap and the mainstream velocity, as well as whether the mixing has been completed in the blade passage.

Enhancement of thermal effect in zero entrainment velocity contact under low surface velocity

2016 ◽  
Vol 230 (12) ◽  
pp. 1554-1561 ◽  
Author(s):  
Binbin Zhang ◽  
Jing Wang
Keyword(s):  
Mathematical Model ◽  
Film Thickness ◽  
Thermal Effect ◽  
Viscosity Index ◽  
Elastohydrodynamic Lubrication ◽  
Surface Velocity ◽  
Surface Waviness ◽  
Entrainment Velocity ◽  
Smooth Contact ◽  
Wedge Effect

In the current study, in order to obtain a thick film thickness under zero entrainment velocity at low surface velocity, the effects of ambient viscosity, pressure–viscosity index of the lubricant, and the surface waviness are investigated numerically based on a thermal elastohydrodynamic lubrication mathematical model. The increasing ambient viscosity and modest waviness can deepen the dimple by a stronger “temperature-viscosity wedge” effect. With the combined effect of ambient viscosity, pressure–viscosity index, and surface waviness, a small centralized dimple in smooth contact evolves into a big classical one together with the disappearance of the former thin droopy film thickness.

Analysis of total leakage of finger seal with side leakage flow

2020 ◽  
Vol 150 ◽  
pp. 106371 ◽  
Author(s):  
Hailin Zhao ◽  
Hua Su ◽  
Guoding Chen
Keyword(s):  
Leakage Flow ◽  
Total Leakage

Thin-Film Flows with Thermoelastically Deformed Boundaries

1978 ◽  
Vol 20 (5) ◽  
pp. 239-245 ◽  
Author(s):  
B. N. Banerjee ◽  
R. A. Burton
Keyword(s):  
Film Thickness ◽  
Point Contact ◽  
Operating Conditions ◽  
Wave Number ◽  
Fluid Viscosity ◽  
Equilibrium Solutions ◽  
Surface Waviness ◽  
Long Wavelength ◽  
Thermoelastic Effects ◽  
Film Flows

Equilibrium solutions are given for the thermoelastic displacements of an initially wavy, moving surface subjected to non-uniform viscous heating derived from a hydrodynamic lubricant film. The configuration studied is similar to a flexibly mounted face seal with one metallic face running against a thermal insulator. Changes in mean film-thickness with changing speed are discussed with reference to earlier analyses which predicted thermoelastic instability and to experiments which illustrated this. The operating conditions approach those where instability was predicted for conditions of fixed mean film thickness; however, no instability is predicted for present conditions where axial load is fixed. Thermoelastic effects upon growth of surface waviness become significant when the sliding speed exceeds u*, given by u* = h1k √( K/µ), where h1 is the initial waviness amplitude, K is the wave number (κ = π/Λ, where Λ is half the wavelength of a sinusoidal waviness), K is the thermal conductivity of the metal, μ is the fluid viscosity, and α is the coefficient of expansion. Past experience has shown that the product h1 k is such that long-wavelength waviness is associated with the lowest u* and therefore magnified relative to shorter wavelength components of the surface topography. Thermal deformations appear to be favourable in their influence on film thickness—except where the unexplained but experimentally observed transition to point contact occurs.

Evaluation of Transverse Shear Effect on Film Delamination in Blister Test

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Wei Wang ◽  
Yong Huang ◽  
Nicole Coutris ◽  
Hongseok Noh ◽  
Peter J. Hesketh
Keyword(s):  
Film Thickness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Phase Angle ◽  
Release Rate ◽  
Transverse Shear ◽  
Shear Force ◽  
Shear Effect ◽  
Blister Test ◽  
Elastic Mismatch

The transverse shear effect has been frequently ignored in determining the debonding-related energy release rate and the phase angle in the blister test, resulting in underestimated values. This study aims to study the effect of shear force on the energy release rate and phase angle prediction in the blister test. A generalized approach is proposed to predict them under the effect of shear force. The predictions show that when the ratio of the film thickness to the debonded film window radius is large (such as 0.05), the transverse shear effect cannot be ignored in determining the energy release rate and the phase angle. The study also further illustrates the importance of including the shear force contribution in estimation and how this importance depends on the film thickness to debonded radius ratio, as well as the elastic mismatch.

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