Numerical Study of Propeller Vibrations and Radiated Noises in the Rudder-Propeller Interaction

The inhomogeneous inflow amplifies the loading fluctuations on the propeller which strengthen vibrations. As a significant source of noises, these vibrations of propeller result in more severe noises on the vessels which are detrimental to the health of crews and marine organisms. The study aimed on the vibrations and radiated noises of propeller is beneficial to ideal design of vessels and better comfort. Hence, the vibrations of blades and radiated noises of 5479 propeller operating in inhomogeneous inflow are numerical predicted in present study. The hydrofoils located upstream of propeller are employed to generate inhomogeneous inflow. Firstly, the loading fluctuations on blades are studied with full-rigid propeller. The vibrations on the trailing edge of blade are compared under different rotational speed. The distributions of vibration are also compared under different rotational speed. Then the radiated noises of the propeller are predicted considering the vibrations of the propeller. Results show that the loading fluctuations on the blade are more intense at leading edge. The vibrations on the blades are dominant at shaft frequency (SF), 4SF and 12SF in the inhomogeneous inflow. Several humps of vibrations are observed at the natural frequencies of the blades. The vibrations at 12SF reaches its maximum when the 12SF approaches the first natural frequency. The deformations and vibrations of blades results in weaker tonal noises but more intense broadband noises.