Predicting Method for Static Leakage of Contacting Mechanical Seals Interface Based on Percolation Theory

Owing to the shortage of mechanical seals leakage mechanism, mechanical problems of mechanical seals interface were investigated based on the Hertz theory. The variation law of porosity of the contact interface with the variation of surface topography as well as the end load were also discussed. Based on percolation theory, the relationship between percolation threshold and porosity of seals interface under different grid layers were explored, and leakage channel model of seals interface was also established, as well as the relationship between leakage rate and surface topography parameters were also established. A static leakage experimental device of mechanical seals was developed, and the leakage rates of mechanical seals was investigated on six groups of sample under different surface topography and medium pressure. The results show that the initial porosity ϕ₀ of the contact interface increased with the increasing of fractal dimension D. The porosity ϕ decreased with the increasing of the end load p_c, and rapidly decreased with the increasing of D and the decreasing of fractal roughness G until compacted without gap. Under the action of face pressure, the porosity of seals interface was greater than 0.593, and leakage channel model of seals interface can be simplified as a single-layer grid percolation model. The more the surface of the seal rings was roughened, the greater the porosity of the seals interface, and the pore throat size of the leakage channel formed by the interconnected pore became larger, resulting in a greater leakage rate at the seals interface. The experimental results were in good agreement with the theoretical predictions, which indicated the rationality of the leakage prediction method.