考虑伴流场中螺旋桨水动力的舰船长轴系校中及优化

Long marine shafting alignment and optimization considering propeller hydrodynamic force in wake field

[目的]针对计入螺旋桨水动力的舰船轴系校中计算,传统方法通常容易忽略船体伴流场的影响,使得螺旋桨水动力计算的结果与真实值之间存在较大偏差,从而导致轴系校中精度下降。[方法]以某舰船长轴系为对象,建立桨-轴-船一体化有限元模型及其伴流场流域模型,利用CFD数值仿真的叠模方法计算螺旋桨水动力;采用流固耦合法将流体计算结果作用于螺旋桨表面,进行轴系校中计算,并得到螺旋桨水动力对轴系整体挠曲线及各轴承状态参数的影响规律。在此基础上,引入多目标优化算法开展轴系多目标优化校中,来解决轴系末端四套轴承间载荷差值过大的问题。[结果]考虑螺旋桨水动力后,轴系尾部挠度变化减小,越靠近螺旋桨处的轴承其载荷所受影响越大,载荷值随进速系数的增大而减小;对比多目标优化前后的轴系校中状态,轴系各轴承之间的载荷差值明显减小,轴系运行状态得到改善。[结论]所提方法提高了计入螺旋桨水动力的轴系校中计算精度,可为轴系校中质量的提升提供参考。

[Objectives]The traditional method of marine propulsion shafting alignment calculation usually ignores the influence of the ship's wake field,causing a large deviation between the computational result of the propeller hydrodynamic force and the real value which results in a decline in alignment accuracy.[Methods]Taking a long marine shafting as the research object,a propeller-shafting-hull integrated finite element model and its wake field model are established,and the propeller hydrodynamic force is calculated using the CFD numerical simulation method.The fluid-structure interaction method is used to apply the fluid computing results on the propeller surface for shafting alignment calculation,and the influence law of the propeller hydrodynamic force on the shafting deflection curve and the state parameters of each bearing are obtained.On this basis,in order to solve the problem of excessive load difference between the four bearings at the end of the long marine shafting,a multi-objective optimization algorithm is introduced for alignment calculation.[Results]When the propeller hydrodynamic force is considered,the deflection change of the shafting tail decreases.The closer to the propeller,the greater the influence of the bearing load,and the load value decreases with the increase of the advance coefficient.Comparing the alignment state of the shafting before and after multi-objective optimization,the load difference between the bearings is significantly reduced and the running state of the shafting is improved.[Conclusions]The proposed method can provide references for optimizing shafting alignment accuracy by considering the propeller hydrodynamic force.