Tribological performance of cavitation and hydrodynamic lubrication in screw pump rotors with Nepenthes-inspired textures and pits

To address severe friction and wear between the stator rubber and metal rotor of submersible screw pumps during the transport of complex downhole media, this study proposed a bionic design approach-introducing textures on the rotor inspired by the microstructure of the Nepenthes peristome. Under shale oil lubrication, systematic simulations were conducted using the Navier-Stokes equations, the Schnerr-Sauer cavitation model, and the mixture multiphase flow model. Results indicated that stable cavitation effectively enhanced oil film pressure and load-carrying performance by suppressing low-pressure regions and strengthening high-pressure regions. This study demonstrates that the lubrication performance is governed by the shape factor of the Nepenthes-inspired texture for the specific operating conditions considered, with both excessively large and small values degrading the load-carrying capacity. Furthermore, orthogonal experiments systematically quantified the influence hierarchy of these parameters, revealing that sliding velocity > shape factor > depth > area ratio. This study offered a theoretical foundation and technical pathway for enhancing the lubrication performance and operational reliability of screw pump friction pairs.