Application of Fractal Contact Model in Dynamic Performance Analysis of Gas Face Seals

Abstract

Fractal theory provides scale-independent asperity contact loads and assumes variable curvature radii in the contact analyses of rough surfaces, the current research for which mainly focuses on the mechanism study. The present study introduces the fractal theory into the dynamic research of gas face seals under face-contacting conditions. Structure-Function method is adopted to handle the surface profiles of typical carbon-graphite rings, proving the fractal contact model can be used in the field of gas face seals. Using a numerical model established for the dynamic analyses of a spiral groove gas face seal with a flexibly mounted stator, a comparison of dynamic performance between the Majumdar-Bhushan (MB) fractal model and the Chang-Etsion-Bogy (CEB) statistical model is performed. The result shows that the two approaches induce differences in terms of the occurrence and the level of face contact. Although the approach distinctions in film thickness and leakage rate can be tiny, the distinctions in contact mechanism and end face damage are obvious. An investigation of fractal parameters D and G shows that a proper D (nearly 1.5) and a small G are helpful in raising the proportion of elastic deformation to weaken the adhesive wear in the sealing dynamic performance. The proposed research provides a fractal approach to design gas face seals.

Analysis of Wear Characteristics of Hydrodynamic Seals During Start- up Using 3D Fractal Characterization and Study of Opening Performance Degradation Mechanism

“…The thickness of the fluid film in the sealing gap is on the micrometer scale, and the inertial force exceeds gravity. This can be expressed by the Reynolds equation [30].…”

Transient response and rub-impact phenomenon of liquid lubricated non-contacting mechanical seals during external pressure fluctuation

“…Furthermore, the expressions of pressure and liquid film density ratio are obtained shown as Eqs. (11) and (12) after Eq. (10) has been discretized.…”

“…In addition, widespread attention has been paid to the rub-impact phenomenon [11]. Face contact could affect sealing performance, such as dynamic behavior, heat generation, friction and wear [12]. Cochain investigates the impact of the face waviness and pressure inversions on the leakage and on the outer fluid entry of mechanical face seals [13].…”