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.

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.

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.

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.

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.

Influence of Additives in Synthetic Oils on Radial Lip Seals

2011 ◽  
Author(s):  
Mathias Klaiber ◽  
Werner Haas
Keyword(s):  
Friction Torque ◽  
Operating Conditions ◽  
Functional Tests ◽  
Dynamic Tests ◽  
Pumping Rate ◽  
Base Oil ◽  
Lip Seal ◽  
Lip Seals ◽  
Elastomeric Materials ◽  
Points Of View

This project has been initiated in order to get a general basic understanding about the influence of additives onto elastomeric lip seal systems. It is necessary to determine the behavior with single additive base oil compounds. Two different synthetic base oils, Polyglycol (PG) and Polyalphaolefin (PAO), are used. Thus 19 different single additive base oil compounds have been reviewed. Two different elastomeric materials NBR and FPM have been taken for all the tests. In several dynamic tests the influences on the sealing systems have been investigated. These included tests for 24 hours to measure the friction torque and tests for 10 hours to measure the pumping rate. Furthermore, the operating conditions during 96 hours functional tests have been determined. A concluding view onto the compatibility, respectively the incompatibility, of the additives in these different points of view will be given.

Elastohydrodynamic Analysis of the Sealing Performance of Rotary Shaft Helix Lip Seals—Part 1

1998 ◽  
Vol 120 (3) ◽  
pp. 476-481 ◽  
Author(s):  
Lou Liming ◽  
Kazutoshi Yamamoto ◽  
Ken Ikeuchi
Keyword(s):  
Analytical Method ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Experimental Results ◽  
Radial Load ◽  
Pumping Rate ◽  
Lip Seal ◽  
Sealing Performance ◽  
Lip Seals

Based upon EHD theory, the sealing performance of a rotary shaft helix lip seal has been analyzed numerically using a complete hydrodynamic lubrication model. In order to verify the analytical method, several experiments are carried out under different operating conditions. After verification by the experimental results, the analytical method is used to calculate the sealing limit and the optimum seal radial load. The effects of the boundary pressure of sump side upon the pumping rate of a seal are discussed.

Thermal Elastohydrodynamic Model of a Radial Lip Seal—Part I: Analysis and Base Results

1999 ◽  
Vol 121 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Kevin Day ◽  
Richard F. Salant
Keyword(s):  
Cross Sections ◽  
Thickness Distribution ◽  
Temperature Dependent ◽  
Pumping Rate ◽  
Lip Seal ◽  
Lubricating Film ◽  
Model Predictions ◽  
Dependent Model ◽  
Temperature Dependent Model ◽  
Shaft Surface

A numerical thermal elastohydrodynamic model of a radial lip seal, with a flooded air side, has been constructed. The shaft surface is modeled as perfectly smooth, while the lip microgeometry is modeled as a uniform distribution of asperities with initially circular cross-sections. The asperities can deform circumferentially as the bulk lip material shears. Both the viscosity of the fluid and the elastic modulus of the lip are temperature dependent. Model predictions include the pressure distribution in the lubricating film under the lip, the film thickness distribution, the cavitation distribution, the pumping rate, and the lip temperature distribution.

Soft elastohydrodynamic analysis of rotary lip seals

2010 ◽  
Vol 224 (12) ◽  
pp. 2637-2647 ◽  
Author(s):  
R F Salant
Keyword(s):  
Film Thickness ◽  
Thermal Effects ◽  
Mixed Lubrication ◽  
Extensive Literature ◽  
Physical Processes ◽  
Pumping Rate ◽  
Capillary Effects ◽  
Lip Seals ◽  
Statistical Approaches ◽  
Reverse Pumping

The extensive literature on the elastohydrodynamic analysis of rotary lip seals is reviewed. Models that predict quantities such as film thickness and reverse pumping rate and that elucidate the physical processes governing the behaviour of rotary lip seals are described. Thermal effects, mixed lubrication, capillary effects, transients, viscoelasticity, statistical approaches, and so-called hydrodynamic seals are discussed.

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