Dynamic Modeling and Noise Prediction Analysis of Composite Material Rim-Driven Thruster

The rim-driven thruster (RDT) adopts a shaftless design, thus eliminating the mechanical excitation and frictional noise caused by shaft movement. In this study, dynamic and noise prediction models of the composite-material RDT have been developed, and numerical examples are given to study the characteristics of radiated-noise RDTs. Studies have shown that the layup method of composite materials has a significant impact on the natural frequency of the blade’s free vibration and further affects the spectral characteristics of the RDT flow-induced noise. In the low-frequency range, the flow-induced load has not yet caused the blade to vibrate, and the noise is mainly hydrodynamic noise. As the frequency increases, the blade starts to vibrate, and a distinct flow-induced vibration spectral pattern is observed. Compared with metal blades, composite material blades can effectively suppress the amplitude of the flow-induced noise spectrum and reduce the total noise of the propeller. The composite RDT generally exhibits lower noise levels than the metal RDT, with a difference of approximately 10 dB observed at the resonance frequency. By comparing the three RDTs with different fiber layer-ups, it can be observed that the fiber-laying angles have a direct impact on the resonance characteristics of the blade and its flow-induced noise. It can be concluded that composite materials have significant potential in the low-noise design of RDT, and a reasonable layup design of the blades can achieve excellent noise-control effects.