螺旋桨脉动压力作用下自航船舶艉部振动数值研究

Numerical Study of Stern Vibration of a Self-Propulsion Ship in Propeller Induced Pressure Fluctuation

为研究静水中航行的船舶在螺旋桨脉动压力作用下的艉部振动特性,基于雷诺平均(RANS)方法,结合剪切应力输运(SST)k-ω湍流模型进行船桨自航数值模拟.将得到的船体表面脉动压力作为外激励,并通过结构有限元模型耦合流场边界元模型进行声固耦合计算,建立了螺旋桨表面力激励自航船舶艉部振动数值预报方法.通过分析螺旋桨表面力在时域与频域内的变化规律,发现叶频分量的幅值远大于其他频率分量的幅值.对于右旋桨,螺旋桨上方的右舷侧压力幅值高于左舷侧压力幅值.通过研究螺旋桨表面力、结构固有特性与振动响应结果之间的对应关系,发现船艉结构耦合模态固有频率应当远离螺旋桨激励力频率,以降低振动响应.通过探究相同激励作用下船艉结构变化对振动响应的影响,发现增加板厚或者安装加强筋可以改变结构固有特性,从而避开共振,达到减振效果.

To study the stern vibration characteristics of the ship sailing in still water under the action of propeller induced pressure fluctuation, the propeller self-propulsion numerical simulation was conducted based on the Reynolds-averaged Navier-Stokes(RANS) method, in combination with the shear-stress transport(SST) k-ω model. Taking the obtained fluctuating pressure on the hull surface as the external excitation, the acoustic-structure coupling calculation was performed through the structural finite element model coupled with the flow field boundary element model, and a numerical prediction method for the stern vibration of the self-propulsion ship excited by the propeller surface force was established. By analyzing the fluctuating pressure characteristics in the time domain and frequency domain, it is found that the amplitude of the blade frequency component is much larger than that of other frequency components. For the right-handed propeller, the starboard side pressure amplitude above the propeller is higher than that on the port side. The analysis of the corresponding relationship between the propeller fluctuating pressure, the structural inherent characteristics, and the vibration response shows that the coupled mode natural frequency should be far away from the propeller excitation force frequency to reduce the vibration response. The exploration of the effect of modifying stern structure on the vibration response at the same excitation indicates that increasing the plate thickness or installing stiffeners can change the inherent characteristics of the structure, thus avoiding resonance and achieving the vibration reduction effect.