The Wavy Mechanical Face Seal Theoretical and Experimental Results

Abstract : This report presents results of theoretical and experimental investigations on the effects of waviness on mechanical face seal performance. Previous work showed how waviness imposed on a seal face leads to reduced friction and wear while creating only a small leakage in a water seal. It was also shown that the waviness must be moved slowly around the seal ring in order that the effect of waviness remain indefinitely. A new device for creating a moving wave with no internal moving parts is described. Experimental results show that the device operates reliably. Results from wavy seal experiments which used this device show that a moving wave can reduce wear by at least a factor of 200 compared to a flat face seal. A model for a wavy seal is presented and refined using the Elrod algorithm for determining cavitation. Predicted results for the wavy seal compare favorably to experimental results. Optimum wavy seal design conditions including the number of waves are established. Theoretical and experimental results are given on the effects of radial taper and high temperature operation on seal performance. Thermal rotation is evaluated experimentally and predicted theoretically. A converging radial taper greatly reduces seal friction and wear during initial operation. Results show how wear progresses across the face. High temperature operation reduces seal friction. A new concept of a self-forming offset-land seal is described. One ring of the seal continually machines an optimum shape into the mating face.