船体破损后非正浮条件下波浪载荷的计算方法

Wave Loads on Damaged Ship under Non-upright Floating Condition

在船舶不沉性理论的基础上 ,采用符拉索夫法分析了不同破舱组合下的船体浮态参数。然后采用线性切片理论 ,计及水线以下破损后船舶由于舱室进水产生的横倾角与纵倾角的影响 ,利用多极展开法求解非对称剖面的二维辐射和绕射流场 ,计算了破损船体非正浮状态条件下的波浪载荷。在一定假定条件下 ,将切片法计算的波浪载荷同静置法计算结果进行了比较 。

The floating parameters including the trimming angle, the heel angle and the increment of draught are determined by the Vlasov′s method according to different combinations of damaged holds based on the linear theory of floatability. The ultimate balance waterline is also determined by the iterative method. Considering the balance waterline as the axis that the ship moves along, the linear strip theory is used to analyze the wave loads on the damaged ship .Two problems are brought out for this ship. One is that the transverse motion is coupled with the longitudinal motion and the coupled motion could not be solved independently, the other is that the section of the damaged ship is asymmetrical and the asymmetry of the hydrodynamic coefficients is necessary to be taken into account. After the asymmetry of the damaged section is trsnsformed into regular sections by the conformal mapping process, the radiational and diffractional fluid field around the asymmetrical sections is solved by applying the multipole expansion method. When the ship length is equal to the wave length, the wave loads on damaged ships in the regular waves are calculated by the linear strip theory under the non upright floating condition, taking the effect on the heel angle and trimming angle and increment of draught caused by the damaged tank inundation below the waterline into account. Then comparative study on both bending moments and shearing forces is performed with the results calculated by traditional design load method for the same assumption, and the change of wave loads varied with the damaged position is discussed in this paper. The results of two different methods are shown that the wave loads are closely related with the load condition and damaged position. The additive wave loads calculated by the linear strip theory usually increase for the damaged ships. The sagging bending moments calculated by the traditional design load method also increase, but on contrast the hogging bending moments decrease because of the load condition and damaged position.