UC San Diego

Mechanical Seals are used throughout the world as the principle method whereby fluid containment may be achieved between a rotating shaft and the shaft housing. As a key component in fluid transportation, storage, and containment, the reliability and performance of mechanical seals is very important. This paper deals with the design, development, and optimization of unique macro/micro- features, used to improve the mechanical seal performance. This Thesis begins with an introductory background of mechanical seal component design, followed by an introduction of external forces and boundary conditions used to describe the seal as an axis-symmetric model. A derivation of the governing equation (Reynolds equation) used to describe fluid pressure between two surfaces is then summarized. Followed with a simplification of the Reynolds equation used to describe hydrodynamic lift under the influence of periodic features. The theory behind laser machining, and the method of creating unique features using a laser is then described. The iterative logic structure of code that I developed is then described; A software tool which uses user defined operation (conducted on imported line segments defining the mask and beam shape boundaries) to define and simulate the laser process, which in turn generates the three dimensional geometry. One of the output files from this software (describing the ablated seal interface geometry) is then imported into a proprietary finite element analysis/ fluid mechanics package. The results of the analysis are used for an optimization study to predict the performance of one such unique macro/micro-feature called a tapered channel (patent pending). Following the FEA analysis, actual testing was performed at the Flowserve facility in Temecula, CA. From the test results, it is concluded that laser ablated macro/micro-feature on the sealing interface of a mechanical seal face can be optimized to improve the sealing performance. This is evident by the 65% reduction in torque, and 69% reduction in the temperature change measured at the sealing interface in comparison to an un-textured seal face