Flow-structure interaction on acoustic radiation of an underwater structure

The purpose of this paper is to study effects of the flow-structure interaction on acoustic radiation of an underwater structure-a hydrofoil. The hydrofoil vibrational modes were analysed numerically, acoustic field resulting from the flow-structure interaction with different flow velocity was investigated by simulation. First, use the software SYSNOISE to analysis the hydrofoil structural and coupled modes. Second, using the fluid dynamic calculation software FLUENT to simulate the flow field around the hydrofoil. The flow fields of different flow velocity are obtained. Then import the results to an acoustic finite element code ACTRAN, and obtain the turbulent fluctuating pressure on the structure surface. Make the pressure as a load applied to the structure surface, and calculate the acoustic field of the structure vibration. The computations showed that the flow-structure interaction makes the structure vibrational modes shift to lower frequencies and adds more low-frequency vibrational modes. The vibrations of the structure strengthen in low frequencies. Therefore the acoustic energy generated from the structural vibrations is increased in low frequencies. At low frequencies, the structural vibrations and radiated acoustic power are stronger, but have a great fluctuation. The fluctuation will decrease as the frequency increases. Also the acoustic power radiated from the flow-structure interaction will increase as the flow velocity increases. There is a stable increment in radiated acoustic power as the flow velocity increases.