Multi-objective optimization design of thermo-hydrodynamic lubrication performance for the wing-shaped textured journal bearing

The thermo-hydrodynamic (THD) lubrication performance of journal bearings is critical to the operational stability and service life of rotating machinery. To achieve a breakthrough in enhancing the THD lubrication performance of journal bearings through surface texturing, we design a novel wing-shaped texture inspired by the falcon's superior flow-guiding and pressure-converging characteristics. A three-dimensional multiphase CFD THD model is established to investigate the influence of wing-texture parameters. The wing-shaped texture is compared with commonly used textures, including rectangle, circle, and triangle designs. To address the complex geometry of the wing-shaped texture, the excessive number of design parameters, and the conflicting objectives, a quadratic response surface model is constructed using central composite design to map parameters to objectives. Multi-objective optimization is then performed by combining NSGA-II with an entropy-weighted TOPSIS method, ultimately identifying the parameter combination that yields optimal THD performance for wing-textured journal bearings. The main findings are as follows: (1) The THD performance of the wing-shaped texture is superior to that of the other three traditional textures. The coefficient of friction can be improved by up to 32.4%, and the average oil-film temperature rise is reduced by 1.08 K. (2) Placing the wing-shaped texture in the middle of the oil film's converging wedge, together with a higher circumferential placement density, delivers better THD performance. (3) After multi-objective optimization, the wing-shaped textures are concentrated at the center of the oil-film high-pressure region, thereby thickening the local film, reducing shear stress and friction, and enhancing lubricant flow and heat dissipation to suppress temperature rise. Consequently, the friction force is reduced by up to 59.3%, the load-carrying capacity increases by 20.5%, and the peak oil-film temperature decreases by 2.19 K. • Wing-shaped textures couple flow guidance and pressure convergence, cutting COF by 32.4% and oil-film rise by 1.08 K. • A 3D CFD-THD model links local flow features to pressure-temperature coordination and texture optimization. • CCD-NSGA-II-TOPSIS optimization cuts friction by 59.3%, raises LCC by 20.5%, and lowers T max by 2.19 K.