Study on hydrodynamic lubrication performance of sector-shaped textures on screw pump stator rubber based on cavitation effect

To address the significant wear of the stator rubber–metal rotor friction pair under the harsh downhole operating conditions of screw pumps, this study aims to increase the lubrication performance of the pair. Inspired by the morphological structure of crucian carp scales, a sector-shaped surface texture is designed and applied to the stator rubber. The impacts of the texture area ratio, included angle, and depth on the film pressure distribution and flow field are studied under complex downhole conditions by developing a finite element model of hydrodynamic lubrication for the friction pair featuring this texture and incorporating the cavitation effects. Furthermore, tribological experiments are conducted for verification. The obtained results demonstrate that the cavitation effect can significantly enhance the oil film pressure and load-carrying capacity of sector-shaped textures. Sector-shaped textures have higher performance than triangular, circular, and square textures. The optimal parameter combination consists of an area ratio of 30%, an included angle of 50°, and a depth of 10 μm. In this condition, the average oil film pressure reaches its maximum value and the most effective fluid dynamic pressure lubrication is achieved, leading to an optimized friction-reduction effect. Tribological experiments are conducted, demonstrating that the specimens with a texture area ratio of 30% exhibit the lowest coefficient of friction. The results obtained in this study provide a theoretical foundation for the bionic texture design of the stator rubber in high-performance screw pumps. The proposed approach facilitates the extension of pump inspection intervals while simultaneously reducing the development costs associated with oil fields.