Optimization design of energy characteristics and broadband noise source mechanisms of annular propellers

The annular propeller, owing to its advantages in efficiency and noise reduction, has emerged as a promising solution for enhancing the propulsion performance of cross-medium vehicles. However, complex multi-medium environments impose dual demands on propeller design-high operational efficiency and low noise–which are difficult to achieve simultaneously in practice. In this study, an orthogonal experimental design approach is employed, considering four key factors: propeller height, blade width, angle of attack, and blade thickness. A corresponding orthogonal table is constructed to generate nine optimized design schemes, followed by numerical simulations. After validating the reliability of simulations using the P4119 propeller, the effects of each parameter on thrust and efficiency are analyzed. The results indicate that the angle of attack is the dominant factor influencing performance. The optimized annular propeller exhibits a 67% increase in thrust and a 15% improvement in maximum efficiency, with higher efficiency in water compared to air. Moreover, the average dipole noise level on the propeller surface is reduced by up to 1 dB. These findings reveal the flow characteristics of annular propellers operating in cross-medium environments and provide a theoretical foundation for the design of high-performance propulsion components.