ELASTOHYDRODYNAMIC ANALYSIS OF REVERSE PUMPING IN ROTARY LIP SEALS WITH MICROUNDULATIONS

An elastohydrodynamic analysis of a rotary lip seal containing microun dulations, incorporating both the fluid mechanics of the lubricating f ilm and the elastic behavior of the lip, has been performed numericall y. The results indicate that, under dynamic conditions, the undulation pattern deforms such that it produces reverse pumping. The reverse pu mping rate is substantial, and overwhelms the natural leakage induced by the sealed pressure, thereby preventing leakage through the seal. T he results also show that the undulations hydrodynamically generate su fficiently high pressures, within the film, to provide load support an d maintain the integrity of the film.