Elastohydrodynamic Analysis of Reverse Pumping in Rotary Lip Seals With Microasperities

1995 ◽  
Vol 117 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Richard F. Salant ◽  
Andrew L. Flaherty
Keyword(s):  
Fluid Mechanics ◽  
High Pressures ◽  
Elastic Behavior ◽  
Lip Seal ◽  
Lubricating Film ◽  
Lip Seals ◽  
Reverse Pumping

An elastohydrodynamic analysis of a rotary lip seal containing microasperities, incorporating both the fluid mechanics of the lubricating film and the elastic behavior of the lip, has been performed numerically. The results indicate that some asperity patterns generate reverse pumping that prevents leakage through the seal. Other asperity patterns are found to generate negative reverse pumping that enhances leakage. In all cases considered, the asperities also hydrodynamically generate sufficiently high pressures to provide load support and maintain the integrity of the film.

Elastohydrodynamic Analysis of Reverse Pumping in Rotary Lip Seals With Microundulations

1994 ◽  
Vol 116 (1) ◽  
pp. 56-62 ◽  
Author(s):  
R. F. Salant ◽  
A. L. Flaherty
Keyword(s):  
Fluid Mechanics ◽  
High Pressures ◽  
Elastic Behavior ◽  
Pumping Rate ◽  
Dynamic Conditions ◽  
Lip Seal ◽  
Lubricating Film ◽  
Lip Seals ◽  
Reverse Pumping

An elastohydrodynamic analysis of a rotary lip seal containing microundulations, incorporating both the fluid mechanics of the lubricating film and the elastic behavior of the lip, has been performed numerically. The results indicate that, under dynamic conditions, the undulation pattern deforms such that it produces reverse pumping. The reverse pumping rate is substantial, and overwhelms the natural leakage induced by the sealed pressure, thereby preventing leakage through the seal. The results also show that the undulations hydrodynamically generate sufficiently high pressures, within the film, to provide load support and maintain the integrity of the film.

Surface Analysis of Radial Lip Seals With Deterministic Micro Cavities on the Shaft

2007 ◽  
Author(s):  
Lyndon Scott Stephens ◽  
Katherine Warren
Keyword(s):  
Functional Groups ◽  
Surface Analysis ◽  
Surface Parameter ◽  
Rotation Surface ◽  
Surface Parameters ◽  
Lip Seal ◽  
Pumping Effect ◽  
Lip Seals ◽  
Areal Surface ◽  
Reverse Pumping

Many approaches have been used to control the reverse pumping effect in radial lip seals. One of those is the use of oriented triangular micro-asperities on the shaft of the seal. This extended abstract presents areal surface parameter measurements from a lip seal with triangular micro-cavities oriented towards the direction of rotation. Surface parameters in the roughness, hybrid and functional groups are presented. The measurements are then discussed and placed in the context of radial lip seal performance.

Numerical Analysis of the Flow Field Within Lip Seals Containing Microundulations

1992 ◽  
Vol 114 (3) ◽  
pp. 485-491 ◽  
Author(s):  
R. F. Salant
Keyword(s):  
Numerical Analysis ◽  
Flow Field ◽  
Shear Deformation ◽  
Leakage Rate ◽  
Shaft Speed ◽  
Rotating Shaft ◽  
Lip Seal ◽  
Lubricating Film ◽  
Lip Seals

The flow field within the lubricating film of a rotating shaft lip seal containing microundulations is analyzed numerically. The results demonstrate that the action of the microundulations can prevent leakage through the seal. The effects on leakage rate of shaft speed, undulation amplitude and wavelength, shear deformation of the undulations, flattening of the undulations, and axial lip profile are presented.

scholarly journals Numerical Investigation of Grooved Shaft Effects on the Rotary Lip Seal Performance with Relative Lip Motion

Lubricants ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 16
Author(s):  
Imane Lahjouji ◽  
M’hammed El Gadari ◽  
Mohammed Radouani
Keyword(s):  
Relative Motion ◽  
Relative Velocity ◽  
Hydrodynamic Lubrication ◽  
Current Model ◽  
Friction Torque ◽  
Rotating Shaft ◽  
Transient Conditions ◽  
Lip Seal ◽  
Lip Seals ◽  
Reverse Pumping

It is generally agreed that radial lip seals are used in systems with a rotating shaft and a stationary lip. However, according to previous work, it was demonstrated that relative motion between the shaft and the lip has substantial effects on the hydrodynamic lifting load and sealing performances. Nowadays, new generations of textured shafts have emerged in order to reduce friction torque and improve reverse pumping, but no study has confirmed the effect of the relative motion between the rough lip and the shaft grooves on the rotary lip seal performances. In this work, an isothermal hydrodynamic lubrication was performed in transient conditions to investigate the effect of the relative velocity between an oblique grooved shaft and a rough lip. After confirming the validity of the current model with respect to previous works, simulations have underlined the effect of the grooved shaft with relative lip motion on the rotary lip seal performance. Indeed, by keeping the same relative velocity between surfaces, it is shown that moving the shaft with a rate higher than that of the lip surface could produce an important reverse pumping and reduce the friction torque significantly, in comparison with cases where the shaft velocity is weaker.

Soft Elastohydrodynamic Analysis of Radial Lip Seals With Deterministic Microasperities on the Shaft

2007 ◽  
Vol 129 (4) ◽  
pp. 851-859 ◽  
Author(s):  
Philip C. Hadinata ◽  
Lyndon Scott Stephens
Keyword(s):  
Friction Coefficient ◽  
Load Capacity ◽  
Asperity Height ◽  
Pumping Rate ◽  
Simultaneous Reduction ◽  
Lip Seal ◽  
Lip Seals ◽  
Lubrication Characteristics ◽  
Triangular Design ◽  
Reverse Pumping

A numerical analysis is conducted to investigate the elastohydrodynamic effect of deterministic microasperities on the shaft of a lip seal. Various geometries of microasperities (triangular, square, hexagonal, and circular) are put into a 100×100μm2 unit cell and are investigated using Reynolds equation. For each shape, the area fraction of the microasperity is varied between 0.2 and 0.8, and the asperity height is varied between 0.3μm and 5μm. The calculation for load capacity and friction coefficient indicates that there are values for asperity height, where the load capacity and friction coefficient are optimized. These optimum heights were reached at 1–3μm. Although the lip seal surface is considered to be smooth, reverse pumping can still be obtained using an oriented triangular design. The Couette flow rate for this asperity showed lubricant is reverted back toward the seal side 2.6 times more than using a conventional lip seal. The addition of microasperities to the shaft surface shows significant improvement in lubrication characteristics for the lip seal in the form of a simultaneous reduction in friction coefficient and increase in the reverse pumping rate.

How to measure the radial load of radial lip seals

2021 ◽  
Vol 68 (3-4) ◽  
pp. 5-12
Author(s):  
Simon Feldmeth ◽  
Mario Stoll ◽  
Frank Bauer
Keyword(s):  
Practice Guideline ◽  
Best Practice ◽  
Parameter Study ◽  
Radial Load ◽  
Measurement Device ◽  
Lip Seal ◽  
Study Results ◽  
Lip Seals ◽  
German Standard ◽  
The University

The radial load of a radial lip seal indicates how strongly the sealing lip is pressed on the shaft. The radial load significantly affects the function of the seal. The German standard DIN 3761-9 describes the measurement of the radial load according to the split-shaft method but leaves room for interpretation. During the revision of the standard, a parameter study was conducted at the University of Stuttgart. This study analyses the influence of the measurement device, the mandrels and the measuring procedure on the results. Based on the study results, recommendations are derived and summarized in a best-practice guideline, which should enable an appropriate and reproducible measurement of the radial load.

Formation of Lubricant Film in Rotary Sealing Contacts: Part II—A New Measuring Principle for Lubricant Film Thickness

1992 ◽  
Vol 114 (2) ◽  
pp. 290-296 ◽  
Author(s):  
G. Poll ◽  
A. Gabelli
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Lip Seal ◽  
Tribological System ◽  
Lip Seals ◽  
Magnetite Particles ◽  
Rotary Speed ◽  
Fluid Film Thickness ◽  
Insight Into

The development of models for the elastohydrodynamic lubrication of rotary lip seals requires the measurement of the film thickness under a real seal. A new method has been developed for this purpose which is based on the use of lubricant oils in which magnetite particles are suspended (so-called magnetic fluids). A change in the fluid film thickness will create a change in the impedance of the coil of the measuring circuit, the magnetic flux of which is directed through the oil film of the contact area. The advantage of this technique is that minimal modifications have to be applied to the tribological system under examination. Initial measurements carried out with a model rubber lip seal provided new insight into the build-up of a lubricant film as a function of the rotary speed and allowed comparison with the results of a theoretical model for the analysis of lip seal lubrication developed in parallel.

Hydrodynamic Analysis of the Flow in a Rotary Lip Seal Using Flow Factors

2004 ◽  
Vol 126 (1) ◽  
pp. 156-161 ◽  
Author(s):  
Richard F. Salant ◽  
Ann H. Rocke
Keyword(s):  
Flow Field ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Present Approach ◽  
Operating Parameters ◽  
Pumping Rate ◽  
Hydrodynamic Analysis ◽  
Lip Seal ◽  
Lubricating Film ◽  
Computationally Intensive

The flow field in the lubricating film of a rotary lip seal is analyzed numerically by solving the Reynolds equation with flow factors. The behavior of such a flow field is dominated by the asperities on the lip surface. Since previous analyses treated those asperities deterministically, they required very large computation times. The present approach is much less computationally intensive because the asperities are treated statistically. Since cavitation and asperity orientation play important roles, these are taken into account in the computation of the flow factors. Results of the analysis show how the operating parameters of the seal and the characteristics of the asperities affect such seal characteristics as the pressure distribution in the film, the pumping rate and the load support.

scholarly journals Differential Sea-Ice Drift. II. Comparison of Mesoscale Strain Measurements to Linear Drift Theory Predictions

1974 ◽  
Vol 13 (69) ◽  
pp. 457-471 ◽  
Author(s):  
W. D. Hibler
Keyword(s):  
High Pressures ◽  
Constitutive Law ◽  
Elastic Behavior ◽  
Local Pressure ◽  
Strain Measurements ◽  
Linear Drift ◽  
Special Cases ◽  
Drift Theory ◽  
Sea Ice Drift ◽  
Frequency Behavior

A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicate that the ice divergence rate and vorticity follow the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds the divergence rate was found to be negative with the vorticity being counter-clockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior was shown to agree with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen (1970) for pack ice. The best least-squares values of the constitutive law parametersηandζwere found to be ≈ 1012kg/s. Using typical divergence rates these values yield compressive stresses of the magnitude of 105N/m which are similar to values suggested by the Parmerter and Coon (1972) ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low-pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer).Calculations were also carried out using a more general linear visco-elastic constitutive law that includes memory effects and which includes a generalized Hooke’s law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates overall a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated “viscosities” similar to the Glen law behavior at temporal frequencies less than ≈ 0.01 h−1.

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