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.

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.

Numerical Study of a Rotary Lip Seal With a Quasi-Random Sealing Surface

2000 ◽  
Vol 123 (3) ◽  
pp. 517-524 ◽  
Author(s):  
Fanghui Shi ◽  
Richard F. Salant
Keyword(s):  
Friction Coefficient ◽  
Physical Mechanism ◽  
Periodic Structures ◽  
Numerical Study ◽  
Thickness Distribution ◽  
Operating Characteristics ◽  
Pumping Rate ◽  
Lip Seal ◽  
Pressure Distributions ◽  
Reverse Pumping

In all previous numerical simulations of the rotary lip seal, the sealing surface was modeled by regular periodic structures. In the present study, a more realistic quasirandom surface is used. A mixed elastohydrodynamic analysis is used to generate predictions of such seal operating characteristics as friction coefficient, reverse pumping rate, film thickness distribution, hydrodynamic and contact pressure distributions, contact area, and cavitation area. The results are in qualitative agreement with previous experimental observations. In the course of the simulations, a new physical mechanism of reverse pumping has been identified.

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.

Finely Striated Lip-Seal Surfaces: Part 1—General Effects

1993 ◽  
Vol 115 (4) ◽  
pp. 620-624 ◽  
Author(s):  
K. To̸nder
Keyword(s):  
Friction Force ◽  
Load Capacity ◽  
Radial Force ◽  
Lip Seal ◽  
Lip Seals

The work presented previously by To̸nder and Salant (1992) is extended and generalized. In that work it was shown that the fine, axially oriented striations found on some lip-seals, under certain conditions, could lead to the total suppression of leakage through a fully lubricated seal. In the present work the behavior of the lubricant annulus is studied, as are the conditions required for leakage suppression. If the latter are met, it is shown that when a certain parameter—here called the seal number—is increased, the lubricant annulus width will shrink. This will lead to a reduction of the friction force. It is further shown that the striated roughness will also generate a radial force or load capacity. This effect does not involve local cavitation.

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.

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.

Effect of friction coefficient on the mixed lubrication model of rotary lip seals

2019 ◽  
Vol 234 (11) ◽  
pp. 1746-1754
Author(s):  
Bingqi Jiang ◽  
Xing Huang ◽  
Fei Guo ◽  
Xiaohong Jia ◽  
Yuming Wang
Keyword(s):  
Numerical Calculation ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Dry Friction ◽  
Friction Torque ◽  
Mixed Lubrication ◽  
Test Method ◽  
Boundary Lubrication Friction ◽  
Pumping Rate ◽  
Lip Seals

This study is devoted to the effect of different coefficients on the calculation results of the rotary lip seal mixed lubrication model. It was proved by experiments that the dry friction coefficient used in the previous models was quite different from the boundary lubrication friction coefficient, which was theoretically more accurate. The pumping rate, friction torque, pressure distribution, and oil film thickness were calculated using both the dry friction coefficient and the boundary lubrication coefficient and the results were quite different. A friction coefficient test method under boundary lubrication condition for numerical simulation of rotary lip seals and an improved method for numerical calculation using the boundary lubrication coefficient instead of the dry friction coefficient were proposed. It was verified that the accuracy of numerical calculation can be improved, and the calculation result was closer to the actual working state.

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.

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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