斜流中船舶水动力及伴流场数值预报分析

Numerical Prediction Analysis of Ship Hydrodynamic Force and Wake Flow Field in Oblique Flow

船舶的斜航状态会造成船尾伴流场不均匀,使螺旋桨桨叶承受周期性的变化力,降低螺旋桨性能并导致空泡现象恶化和船舶振动。为预报斜航状态下船舶水动力及船尾伴流场,采用混合网格技术,利用RANS方法和VOF模型,考虑自由液面的影响对KCS船开展了直航和斜航状态下数值预报分析。首先对船舶直航状态进行数值分析,得到的结果与试验结果比较接近,进而对船体在斜航状态下进行了数值模拟。结果表明,漂角的存在会对船舶阻力产生较大影响,且对球首底部和船尾舭部压力分布影响较大,导致兴波阻力增大,船尾伴流场均匀性变差,对螺旋桨激振力不利。

The ship under oblique route causes non-uniform wake flow field,and this makes the propeller suffer periodic loads variation,which may lowers the performance of the propeller,aggravates the cavitation phenomenon and causes ship vibration.In order to predict the hydrodynamic force and the ship wake flow field,the hybrid grid technology is adopted and numerical prediction analysis on KCS ship under direct and oblique route is carried out,considering the influence of free surface by employing Reynolds-Averaged Navier Stokes(RANS)method and VOF model.Firstly,the numerical analysis of hydrodynamic force under direct route is carried out,and the results agree well with the experimental data.Then,the numerical simulation of hydrodynamic force of the ship under oblique state is carried out.The results show that the existence of drift angle greatly affects the ship resistance,as well as the pressure distribution at the bulbous bow and stern bilge,resulting in the increase of wave resistance,worse uniformity of wake flow field and disadvantages to the exciting force of the propeller.