推进器脉动压力对半潜式平台振动的影响

以N503型半潜式支持平台为对象，在循环水槽中开展推进器缩比模型脉动压力试验，利用相似关系换算得到平台推进器作用在船体结构上的脉动压力。采用有限元法建立平台的实尺度模型，计算前5阶推进器脉动压力对上层建筑振动的影响，并与平台中其他主要设备引起的上层建筑振动进行对比。结果表明：航行状态下推进器引起的脉动压力远大于动力定位状态。在动力定位状态下，上层建筑中的振动加速度随着叶频阶数增加而逐渐降低，推进器输出功率与结构振动成正比。推进器脉动压力引起的振动集中在叶频线谱上，引起的上层建筑的振动总级与空调机组相当。在50 Hz以下频段，应首先考虑主机和推进电机的振动控制，当高于该频率时应考虑上层建筑中空调机组的振动控制。

Effect of Propeller Pulsating Pressure on Vibration of Semi-Submersible Platform

Taken N503 semi-submersible support platform as the object, the pulsating pressure of propeller scale model is tested in circulating water tank. The pulsating pressure on hull structure caused by propeller is obtained by model test data and conversion relationship. The real scale model of the platform is established by finite element method. The influence of the first five stage pulsating pressure on the vibration of superstructure is calculated and the vibration is compared with the superstructure vibrations caused by other major equipment in the platform. The results show that the pulsating pressure caused by propeller in the navigation state is much larger than that in the dynamic positioning state. In the dynamic positioning state, the vibration acceleration of the superstructure gradually decreases with the increase of the leaf frequency and the output power of the propeller is proportional to the magnitude of the vibration. The vibration caused by propeller pulsating pressure is concentrated on leaf frequency line spectrum and the vibration level is equivalent to that of the air conditioning unit. When the frequency is lower than 50 Hz, the vibration control of the main engine and propulsion motor should be considered first. Otherwise, the vibration control of the air conditioning unit in the superstructure should be considered.