Performance Optimization of a Supercritical Carbon Dioxide Centrifugal Compressor with Nonuniform tip Clearance Based on the NSGA-III Optimization Algorithm

This work focused on the influence of nonuniform tip clearance on the performance characteristics of supercritical CO₂(SCO2) compressors. A parametric model of the nonuniform clearance at the impeller blade tip was constructed using Bézier curves. This study examined the impact of the nonuniform blade-tip clearance on the compressor’s aerodynamic performance. An automated closed-loop multi-objective optimization process based on TUI control was implemented using the nondominated sorting genetic algorithm III (NSGA-III). The geometric parameters of the nonuniform clearance corresponding to optimal performance were obtained. The performance and flow-field characteristics of the model under both optimal and baseline conditions were then compared and analyzed. The results show that the performance of the supercritical CO₂ compressor with nonuniform blade tip clearance was significantly improved. Under the design conditions, the efficiency increased by 3.08%, the pressure ratio increased by 1.55%, and the turbulent kinetic energy on the impeller’s S1 flow surface decreased by 29.3%. High-entropy production areas in the impeller and diffuser channels were significantly reduced, with entropy production rates decreasing by 37.1% and 53.4%, respectively. Unsteady flow-field analysis results show that pressure pulsations at the diffuser outlet decreased by 18.4%. Compared with traditional optimization methods, the approach proposed here greatly improves computational efficiency and has important implications for the aerodynamic performance optimization of supercritical CO₂ compressors.