Investigation into fluctuating pressure and radiated noise of a propeller induced by fluid-structure interaction

This study investigates the fluid-structure interaction (FSI) in ship propellers, focusing on its impact on hydrodynamic performance and noise characteristics. The "Royal Princess” propeller serves as a case study for examining surface pressure fluctuations and acoustic signatures in elastic propellers under FSI effects. A two-way coupled FSI numerical framework was established, integrating Large Eddy Simulation (LES) with the Finite Element Method (FEM), while the Ffowcs Williams-Hawkings (FW-H) acoustic analogy was employed for noise prediction. This setup enabled a systematic examination of surface pressure fluctuations, structural vibration modes, and noise spectrum characteristics across a range of rotational speeds. The results demonstrate that fluid–structure interaction (FSI) is a critical factor influencing propeller noise above 500 Hz. At a low rotational speed of 15 rps, the solid structure remains unexcited, and the propeller noise is dominated by fluid motion, similar to the case under the rigid assumption. At speeds of 20 rps and above, the first and second natural frequencies of the blade are excited, acting at 570 Hz and 1190 Hz, respectively, and producing distinct broadband noise characteristics. This effect elevates the noise level at these frequencies by 10–20 dB compared with the rigid assumption. At 40 rps, the second mode causes a significant increase in the noise level across the entire subsequent spectrum. The noise measured at 35 rps is higher than that at higher speeds, indicating the occurrence of fluid–structure coupling resonance under this condition, which leads to an abnormal increase in the noise level.