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为了研究多源激励下水中有限长加肋圆柱壳体的声振特性,由Flügge壳体振动理论建立了单频多源激励下水中长度为2L的有限长加环肋和纵肋壳体的声振耦合方程。将壳体结构位移、表面声压以及激励力展开为各阶模态与波形的组合形式,将肋骨作用表示为附加阻抗与各阶模态的叠加,导出了单频多源激励下加肋壳体振动和声辐射的解析表达式,并通过算例研究了肋骨、激励源相对位置对壳体声振特性的影响。计算结果表明:肋骨改变了壳体的共振特性,使共振频率处壳体的表面平均振速级降低,导致共振频率附近的辐射效率级增加3-5dB;将集中力转化为轴向分布的激振力可降低壳体的中高频处辐射声功率级,在频率f>500Hz频段,轴向距离为L/4时的幅值比单点激励低3-5dB;将集中力转化为周向分布的激振力可降低壳体的低中频处辐射声功率级,在f<150Hz频段,周向相距为π/2和π/3时的辐值比单点激励低7-9dB。本文研究结果可为水下结构的振动与噪声控制提供理论依据。
In order to study the acoustic vibration characteristics of a finite length cylindrical shell with a finite length in a multi-source excited water, the finite length annular rib and longitudinal rib shell with a length of 2L under single-frequency multi-source excitation are established by the vibration theory of the Flügge shell. Vibration coupling equation. The structure displacement, surface acoustic pressure and excitation force of the shell are expanded into the combinations of modes and waveforms of various modes. The rib effect is expressed as the superposition of additional impedances and modes. Body vibration and acoustic radiation, and studied the influence of the relative position of rib and excitation source on the shell acoustic vibration characteristics through a numerical example. The calculation results show that the ribs change the resonance characteristics of the shell and reduce the average surface velocity of the shell at the resonance frequency, resulting in an increase of 3-5 dB in the radiation efficiency level near the resonance frequency. Vibration can reduce the radiation power level at the middle and high frequency of the shell. When the axial frequency is greater than 500Hz, the amplitude is 3-5dB lower than the single point excitation when the axial distance is L / 4. The concentrated force is converted into the circumferential distribution The excitation force can reduce the radiation sound power level of the shell at low IF. When the frequency is less than 150Hz, the amplitude at the circumferences of π / 2 and π / 3 is 7-9dB lower than the single point excitation. The results of this paper can provide theoretical basis for vibration and noise control of underwater structures.