Simulation of a hydraulic rod seal with a textured rod and starvation

A numerical analysis of a reciprocating hydraulic rod seal with a textured rod has been performed. The sealed pressure during the instroke is elevated, while that during the outstroke is atmospheric. The analysis consists of coupled fluid mechanics, contact mechanics and load support analyses, and takes account of starvation. The fluid transport, friction force, film thickness distribution, contact pressure distribution and fluid pressure distribution in the sealing zone have been computed for a polyurethane U-cup seal. Starvation during the instroke dominates the seal behavior at moderate to high rod speeds. The results indicate the friction force exerted on the rod by the seal cannot be significantly reduced by texturing the rod, and could even be slightly increased.