艉斜浪下船舶倾覆特性直接CFD数值模拟

Direct CFD simulation of ship capsizing in stern quartering waves

  • 摘要:
      目的  由纯稳性丧失引发的船舶倾覆是国际海事组织(IMO)针对船舶第二代完整稳性的重点研究问题之一。
      方法  基于黏性流理论建立CFD数值模拟方法,结合动态重叠网格技术与操纵运动反馈控制模块,对带螺旋桨、带舵的自航船舶在艉斜浪下保持航向操纵运动进行数值模拟,预报纯稳性丧失下船舶的六自由度运动,并对船舶的失稳运动及倾覆特性进行直接评估。
      结果  结果显示,船舶在持续的稳性丧失情况下会产生大幅度的横摇运动,最终会因横摇角过大而导致倾覆现象的发生;在稳性丧失的状态下,船舶艏摇角显著增大,说明船舶在该状态下依靠操舵已无法有效控制船舶航向,会导致较为明显的横甩现象。
      结论  所做研究表明,采用CFD方法模拟船舶失稳运动与倾覆现象准确性较高,研究成果对于研究船舶第二代完整稳性衡准具有一定的参考意义,可为纯稳性丧失的直接稳性评估方法研究提供支撑。

     

    Abstract:
      Objective  Ship capsizing induced by pure loss of stability is an important issue for research on the second-generation intact stability criteria proposed by IMO.
      Methods  A CFD solver based on the viscous theory is developed in combination with the dynamic overset approach and feedback controller for ship maneuver behavior, thereby simulating the course-keeping of a free-running ship with rudders and propellers in stern quartering waves. 6-DOFs motions are predicted for the ship under pure loss of stability with stability failure mode and capsizing assessment.
      Results  The results indicate that large amplitude roll motion occurs with the continuous loss of stability, and the extreme roll eventually leads to the ship capsizing. The yaw angle increases significantly with the variation in roll angle, which indicates that the rudder deflection is unable to control the ship's course effectively, resulting in the broaching phenomenon.
      Conclusions   The results of this study demonstrate that the CFD approach can accurately simulate the stability failure mode and capsizing of a ship, providing references for research on the second-generation intact stability criteria, and technical support for the development of direct stability assessment under pure loss of stability.

     

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