Effect of snake-biomimetic surface texture on finger sealing performance under hydrodynamic lubrication

Abstract

In recent years, surface textures have been found with extraordinary potential to improve lubrication of friction pairs, reduce viscosity, and improve wear resistance. To study the effects of surface textures in the finger sealing, as inspired by the snakeskin, four texture forms with different layouts are presented in this paper and comprehensive performance analysis is carried out under the condition of hydrodynamic lubrication. First, a numerical model of finger seals with surface textures under hydrodynamic lubrication is proposed based on the Reynolds equation. Then, finger seal performance analysis is carried out considering different texture surfaces in terms of forms, layouts, and geometric parameters. The results show that: (1) When the texture profile is consistent with the direction of rotor motion, it is beneficial to create better hydrodynamic pressure and improve sealing performance; (2) To achieve good friction and wear resistance of a textured finger seal, the texture depth should be as shallow as possible (<25 μm); (3) When the texture depth is equal to the seal clearance, the average dimensionless pressure reaches the greatest with smallest friction coefficient; (4) With the increase of the texture density, the average dimensionless pressure increases rapidly first and then gradually flattens, while the friction coefficient performs oppositely. Given the manufacturing economy, the suitable texture density is around 20%∼40%.

Effects of Snake-Bioinspired Surface Texture on the Finger-Sealing Performance under Varied Working Conditions

“…Based on the Reynolds equation, the authors have derived a mathematical model of surface textured finger seal under hydrodynamic lubrication to study the impact of surface texture parameters on the sealing performance [28]. Based on this, the state equation considering the viscosity-temperature effect is derived in the following sections to further explore the effects of surface textures on sealing performance under varied working conditions.…”

“…Before the formal calculation, α and Err p are calculated trial-wise to satisfy the requirements in terms of both efficiency and accuracy. According to the trial calculation results, α and Err p are set as 1.9 and 10 −5 respectively [28].…”

“…Motivated by the snake-bioinspired texture effectively improving the tribological properties of the friction interface, the authors proposed four snake-bioinspired textures (e.g., diamond, ellipse, hexagon, and triangle) for finger seals. They evaluated the influence of the arrangements and parameters of surface textures on finger-sealing performance [28]. The results have shown that it can significantly improve the sealing performance at the texture density of 20~40%, the texture depth of 5~25 µm, and the texture arrangement consistent with the rotation direction of the rotor.…”

Numerical investigation on sealing performance of non-contact finger seal with herringbone groove surface topography

“…As a compliant rotor seal, finger seals are well known for their low leakage rate and long service life, which makes them have great potential in the application of aero-engines and gas turbines [1,2]. Finger seals are classified into contact and non-contact finger seals (NCFSs).…”

“…several common characteristics can be identified (1). From the inlet HP zone to the outlet LP zone, the velocity of the fluid decreases correspondingly (2). Owing to the influence of the rotor rotation, the flow velocity on the left side of the interface is slightly higher than that on the right side.…”