CAVITATION IN MECHANICAL SEAL AND ITS EFFECT ON SEALING PERFORMANCE

摘要

Mechanical seals are widely used in industries to seal pressurized fluids around rotating shafts in equipment ranging from centrifugal compressors to reactor coolant pumps. To satisfy the requirements of more severe operation conditions in applications the grooved mechanical seal were used to increase the bearing capability of fluid film and decrease the friction between the end faces. Among all these grooves developed in the past decades, the spiral groove is the most frequently used form [1]. So far most of the researches concerning spiral grooved mechanical seal are gas lubricated. Only a little attention has been pay to the cases which use liquid as the sealant, such as the oil film lubricated mechanical seal [2]. However, liquids have been used as the sealant in many other kinds of mechanical seals such as the coned end face mechanical seal and waved end face mechanical seal used in reactor coolant pumps. As the liquid has a much larger viscosity than gas, the bearing capability generated by liquid film is much larger than that formed by gas film. This will benefit the stability of mechanical seals. However, most of the liquid lubricated mechanical seals encounter the phase changing problems. Cavitation is one kind of those problems, induced by the depressurization. It has been proved that the geometric structure of the surface plays an important role in cavitation [3]. In this work, water lubricated mechanical seal with spiral grooves is investigated numerically taking the cavitation effect into account.