基于三种方法的螺旋桨敞水性能数值预报

  目的  船舶横摇的准确预报对于船舶耐波性、稳性以及操纵性的研究具有十分重要的意义，但船舶横摇运动受流场粘性效应的影响很大，计算中存在较多非线性因素，因而并不适于常用于研究船舶运动的传统势流理论。为解决这一问题，  方法  采用基于OpenFOAM软件开发的naoe-FOAM-SJTU求解器，分别通过欧拉方法和RANS方法对S60船模典型二维横剖面的强迫横摇进行数值模拟，同时，模拟分析DTMB 5512不同三维船模的自由与强迫横摇运动。  结果  在成功将横摇阻尼力矩的不同成分分别计算出来后发现，其中漩涡阻尼所占的比例最大，摩擦阻尼所占的比例最小，而舭龙骨在一定的横摇角度范围内则减小了横摇阻尼力矩。  结论  该结果揭示了横摇参数对船舶横摇运动及横摇阻尼力矩的影响，对准确预报船舶的横摇运动具有重要意义。

Empirical calculation of roll damp-ing for ships and barges

During the ship design procedure, the analysis of ship rolling motions is of great significance because the rolling motions have extraordinary effects on the sea-keeping, maneuverability and stability of a ship. It is difficult to simulate rolling motions due to the effect of viscosity, which causes many nonlinear components in computation. As such, the potential theory used for other ship motions cannot be used for rolling motions. This paper simulates the rolling motions of the DTMB 5512 ship model and the ship transverse section of the S60 ship model with a naoe-FOAM-SJTU solver using the Reynolds Averaged Navier Stokes (RANS) method based on the OpenFOAM. The results of rolling motions are compared with the experimental data, which confirms the reliability of the meshes and results. For the ship transverse section of the S60 ship model, the damping coefficient is divided into three parts with the Euler and RANS methods:friction, vorticity and wave parts. For the DTMB 5512 ship model, the damping coefficient is also respectively analyzed, including the friction, vorticity, wave and bilge keel parts. The results in this paper show that the vorticity part accounts for the greatest proportion, while the friction part accounts for the least, and the bilge keels reduces the damping moment to a certain extent which shows the effect of rolling parameters on rolling motions and moments.