Low frequencies radiation characteristics of a submerged cylindrical shell and its active control

The radiation characteristics of a submerged finite cylindrical shell at low frequencies were investigated based on its vibration modes and acoustic radiation modes. The contribution of each circumferential vibration mode to the radiated sound was observed. Then, under a certain circumferential mode, axial vibration modes were divided into an axial odd-mode group and an axial even-mode group, and the correspondance relationships between each vibration mode group and acoustic radiation modes at low frequency were inspected. The results show that at low frequencies, only the first few circumferential vibration modes contribute to the sound power radiated from a submerged finite cylindrical shell excited by radial point forces; under a certain circumferential mode, the sound power radiated by the odd (even) axial vibration modes group corresponds to the acoustic radiation mode with the same circumferential mode and even (odd) axial modes. The sound power radiated from a submerged finite cylindrical shell can be restrained by controlling the sound power of the dominant radiation modes.