螺旋桨激励水下艇体振动的试验及数值研究

为考虑螺旋桨真实激励特性,在循环水槽中开展艇尾伴流场中螺旋桨诱导艇尾脉动压力及螺旋桨激励水下艇体振动响应的测量试验。试验结果表明:脉动压力幅值在叶频处最大,且随螺旋桨负载增加而增大,随与螺旋桨之间距离的增大而减小,四叶桨脉动压力在尾翼后的高伴流区幅值较大,五叶桨则在尾翼之间的低伴流区幅值较大；大部分测点的振动响应幅值随螺旋桨负载增加而增大,但也存在叶频处幅值较小和未随负载增加而增大的情况；五叶桨激励引起的侧向振动较四叶桨有所增强而轴向振动有所减弱；特定谱峰频率处振动响应幅值呈一阶弯曲振型,其频率范围与有限元计算结果较为一致。综合采用计算流体动力学、有限元和模态叠加法建立螺旋桨激励水下艇体振动响应的数值计算方法,通过计算与试验结果的对比发现,该方法的计算结果与试验结果吻合较好,相比于采用单位简谐激励的谐响应分析方法更加接近真实情况。

Experimental and numerical study on propeller induced vibration of underwater hull

To consider the real excitation characteristics of propeller, the measurement experiment of stern fluctuating pressure and underwater hull vibration response induced by propeller in stern wake field was conducted in circulating water channel. The experiment results show that:the fluctuating pressure has the maximum amplitude at BPF(blade-passing frequency), increases with the increase of the propeller load and decreases with the increase of the distance to propeller; the four-blade-propeller has larger amplitude at high wake region after rudders while the five-blade-propeller at low wake region between rudders; the vibration response amplitude at most of the monitor points increases with the propeller load, but there are cases that have less amplitude at BPF and no increase with propeller load; the lateral vibration induced by five-blade-propeller increases while the axis vibration decreases compared with four-blade-propeller; the vibration response amplitude at specific peak frequency presents the 1st order bending mode, and its frequency range relatively agrees with the numerical result of finite element method. The computational fluid dynamics, finite element and modal superposition method were combined to establish a numerical method to evaluate propeller induced vibration response of underwater hull. The comparison between numerical and experiment results illustrates that the numerical results provide a good agreement with the experiment results and are closer to reality than the harmonic response analysis method which uses unit harmonic excitation.