14000 kW救助船恶劣海况下失速系数数值研究

Numerical Study on Speed Loss Coefficient of 14 000 kW Rescue Ship in Severe Sea Conditions

为研究救助船舶在恶劣海况条件下的失速性能,保证救助船舶的航行安全性,选取非线性势流计算方法和黏流CFD方法,计算KCS船在静水和规则波中的波浪增阻及船舶运动。将计算结果与船模试验数据进行对比可得:2种数值模拟计算方法在计算波浪增阻时,误差均在3.6%以内,但非线性势流理论方法相较于黏流CFD方法能够大量节约时间。因此,选定非线性势流理论计算方法为救助船数值试验计算方法,将救助船非线性势流理论计算结果与静水船模试验结果对比,在设计航速17.5 kn时,阻力误差绝对值为2.22%,选取方法有效。根据ITTC 2014年提出的失速系数计算方法进行目标船型失速预报,在设计航速17.5 kn条件下,5级海况时失速系数最大,为0.93,7级海况时失速系数最小,为0.66。

In order to study the speed loss of rescue ship under harsh sea conditions and ensure the navigation safety of rescue ship, the nonlinear potential flow calculation method and viscous flow CFD method are selected to calculate the wave drag increase and ship motion of KCS ship in still water and regular waves. The calculation results are compared with the ship model test data, and it can be obtained that the errors of the two numerical simulation methods are within 3.6% when calculating the wave drag increase, but the nonlinear potential flow theory method can save a lot of time compared with the viscous flow CFD method. Therefore, the nonlinear potential flow theory calculation method is selected as the target ship type calculation method. Comparing the calculation results of the rescue ship’s nonlinear potential flow theory with the still water ship model test results, when the design speed is 17.5 kn, the absolute value of the resistance error is 2.22%, and the selection method is effective. Finally, according to the calculation method of ship speed loss coefficient proposed by ITTC in 2014, the target ship type speed loss prediction is carried out. Under the design speed of 17.5 kn, the ship speed loss coefficient is the largest at sea state level 5, which is 0.93 at this time, and the ship speed loss coefficient is the smallest at level 7 sea state, which is 0.66 at this time.