水下通气空泡航行体结构模态及冲击响应研究

Mode and impulse response of ventilated cavitating underwater vehicles

将航行体水下通气空泡简化为空气弹簧,并基于结构水下附加质量与空气弹簧作用原理,推导了水下通气空泡航行体在局部通气空泡包裹下的流固耦合振动方程.基于该振动方程,对通气空泡航行体在不同空泡长度包裹下的模态频率以及冲击载荷作用下的结构响应进行了分析,并将结果与将通气空泡简化为真空情况的计算结果进行对比.研究结果表明,结构的模态频率随通气空泡长度的增大而波动增大;通气空泡刚度对结构模态频率的影响随模态阶数的增大而减小;在冲击载荷作用下,通气空泡长度越大,响应幅值越小、响应频率越高.

The ventilated cavitation is first predigested to be an air suspension,and then,based on the theory of added mass and air suspension,the FSI vibration equation of ventilated cavitating underwater vehicles is deduced.The change of natural frequency of underwater vehicle,which is enwrapped by ventilated cavitation of different length,is computed,and the influences of ventilated cavitation on vibration of underwater vehicles are investigated.Based on these,the response of structure,impacted by a transverse force,has been analyzed.The results reveal that the natural frequency of structure increases wavily as well as the increment of the length of ventilated cavitation.It is also found that the first step mode frequency is influenced mostly by the elasticity of ventilated cavitation,besides,the influence of ventilated cavitation becomes weaker with the increase of mode step;Under the impact force,the response of amplitude becomes smaller and the response of frequency becomes bigger with the increment of the length of ventilated cavitation.