Numerical Study of the Effect of Lip Surface Roughness on Lubrication of Radial Shaft Seals with a Simple Sinusoidal Model

Abstract

The effect of lip surface microtopography on lubrication of radial shaft seals is studied numerically. Numerical analysis of hydrodynamic flow at the lip is conducted with a simple sinusoidal wave as a lip surface asperity model. In order to understand the effects of lip surface microtopography on micro EHL, amplitude, wavelength, curvature and asperity ratio on film formation are investigated. It is found that the wavelength, the curvature and the aspect ratio significantly affect film formation and the coefficient of friction, and that coefficient of friction is influenced not only by minimum film thickness but by the average film thickness.

Rotary Lip Seal Operation with Environmentally Acceptable Lubricants

“…The surface equivalent is deduced from the surface roughness characteristics and hence these models typically require from experimental results for its calibration. Further discussion on the topic can be found in [54] and [15]. Additionally, experiments showed that the shaft velocity-friction torque curve shows a positive ordinate intercept in rotary lip seals.…”

“…This way, the radial and circumferential deformations resulting from the hydrodynamic viscous shearing could be computed. Some researchers used the Boussinesq half-space approximation to account for the seal distortion [54]. However, Elgadari [55] showed that this is inaccurate, leading to erroneous results.…”

“…A larger contact width or a larger number of asperities also leads to a greater load-carrying capacity. In fact, the equivalent surface profile determines to a large degree the results obtained with this kind of model [15], [54]. The results suggest that, under the common stern tube seal operating conditions, part of the load is carried by direct asperity contact [68].…”