Sealing Performance Analysis Of Mechanical Seal Under Static Pressure Based On Percolation Theory

So far, there are lot’s of research about the performance of mechanical seal used in gas turbine pump under rotating condition, as the mechanical seal used in gas turbine will be in static pressure for a long time, the problem of percolation phenomenon under static pressure become more and more severer, study about percolation theory under static pressure is extremely urgent. When in static pressure condition, fluid flow between mechanical seal end face is under mixed lubrication state, there exists certain shortcomings in applying Reynolds equation which is suitable for full lubrication to describe mixed lubrication. So the non-groove, groove and porous mechanical seal percolation model are established based on porous media model which is suitable for the description of mixed lubrication. The performance of contacting mechanical seal are theoretically and experimentally analyzed, the work will lay the foundation to the further application of percolation theory in mechanical seal.Firstly, analytic solution model and numerical solution model had been obtained based on porous media model. Equivalent film thickness was obtained based on plastic contacting model, so as porosity and permeability could be calculated accordingly. Viscous drag was added to N-S equation, a new analytical solution model was gained, free and porous media flow model in COMSOL was used to get the numerical solution.Secondly, contacting mechanical seal model was regarded as the study object, the effects of different geometric parameters and operating parameters on leakage rate were analyzed. The results showed that end face roughness, seal medium pressure, end face length, spring pressure and medium viscosity were the main results that effect static pressure leakage rates, analytic results were used to verify the correctness of numerical results. In addition, in order to verify the reliability of theoretical results, test-bed was constructed to conduct the experimental analysis.Finally, concentric grooves mechanical seal and ellipse mechanical seal were regarded as the studying object, the effect of geometric parameters on sealing performance were analyzed based on numerical model. The results showed that concentric groove number, groove width and medium viscosity had great effect on leakage rate, while groove depth, groove dam width and roughness of groove had barely effect on leakage rate. Angle inclination, axial ratio of ellipse porous and medium viscosity had great effect on leakage rate, while ellipse porous depth, roughness of ellipse porous had barely effect on leakage rate.In this paper, percolation model of mechanical seal under static pressure were established, the effect of different geometric parameters and operating parameters on leakage rate were analyzed, this method have opened a new way to analyze the sealing performance of mechanical seal under static pressure, it also might give some suggestions to the geometric optimization of mechanicals seal end face.