基于边界元法的带空泡航行体的附加质量研究

Research on added mass of cavitating vehicles by boundary element method

采用边界元法计算了水下航行体在不同空化数下的定常轴对称空泡形态及流场。考虑航行体在此定常基本流中作刚体微幅振动,基于船舶有航速辐射水动力的计算方法,在频域中计算了带局部空泡航行体的轴向、横向和转动附加质量(惯性矩)。研究了带空泡附加质量与振动频率的关系。高频时,各附加质量分量都趋于定值;低频时,附加质量随频率迅速变化,其中轴向附加质量甚至变成负值。针对这种特殊的现象,从含有空泡面的流场对航行体非定常扰动的响应特征出发,给出了一种解释。

Boundary element method is used to calculate the steady partial cavity of underwater vehicles and steady flow around them. And, the approach taken in solving the problem of ship motions in seaway is applied to underwater vehicles with cavity. Here, the calculated steady flow is taken as basic flow. This ap-proach is used to calculate the added masses （or inertia moment） in axial, lateral and rotational motions of cavitating vehicles in frequency domain. The influence of frequency on the added masses is studied. All the added masses approach to constants as the frequency increases and vary rapidly when the frequency is lower. Especially, the axial added mass even becomes negative, which is very interesting and out of expec-tation. An interpretation about how this happens is given from the characteristics of the field with surface.