【作者】 单铁兵；

【导师】 黄胜；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋结构物设计制造， 2008， 硕士

【摘要】 近年来,各国都积极投入对操纵运动船舶水动力性能的研究,目的在于不断提高船舶操纵性预报的准确性,实现真正意义上的对船舶运动的仿真模拟。船舶的水动力性能研究计算对准确预报船舶的操纵性能起着至关重要的作用。本文运用CFD软件计算了螺旋桨的敞水性能,得出了不同进速系数下螺旋桨的推力系数KT,扭矩系数Ko,并与试验值进行对比。结果表明CFD计算敞水螺旋桨的水动力性能是可行的。分别利用FLUENT和卡耳玛科夫两种计算方法,计算了敞水中螺旋桨被锁定时的水动力性能。得出不同进速下螺旋桨锁定时的阻力分布以及横向力分布。运用刚体转动稳定性的原理,计算了敞水条件下螺旋桨自由旋转时的水动力性能。给出了不同进速下螺旋桨受到的阻力值以及临界转速。计算结果表明随着进速V的增大,自由旋转的螺旋桨达到临界状态时的转速N也不断增加。同时临界轴向力逐渐增加并表现为阻力,螺旋桨旋转方向与正常桨一致。计算了考虑船尾伴流影响后内桨锁定或外桨锁定,以及内桨自由旋转或外桨自由旋转时所受到的作用力。比较了FLUENT和卡耳玛科夫两种方法的计算结果。本文利用标准K-ε湍流模型计算了具有自由表面的粘性绕流场。计算不同航速下的船舶所受的阻力值,并与试验值比较,通过分析发现:在低速时,计算值比试验值要大,而在高速时CFD计算值偏小。但总的来说两者差别不大。计算阻力曲线和试验阻力曲线的变化趋势基本一致,能较好地反映出船体的阻力性能。验证了CFD模拟带自由液面船体的粘性流场是可行的。在前一章的基础上进一步探讨了船体周围以及螺旋桨内桨及外桨盘面处的伴流分布,模拟了船体尾部桨盘面处的伴流场。分别计算了裸船体和附体船桨盘面处的三向速度比随角度变化的分布情况;计算了三向平均速度比沿径向的分布情况。计算了平均轴向,切向以及径向速度比随Fr数的变化情况,发现随着Fr的增大,船舶内外桨盘面处的平均轴向速度比增加。说明航速V的变化对船尾伴流分布是有影响的。建立了船舶操纵性运动模型。建模时,分别考虑了作用在船体,桨,舵上的力和力矩以及三者之间的相互干涉。利用前几章计算得出的各水动力值,代入MMG方程中,并用龙格库塔法对操纵运动的数学模型求解,从而实现船舶的运动仿真。本论文可为进一步研究大型船舶快速性以及操纵性能提供一些参考和依据。更多还原

【Abstract】 Recently, in order to continuously improve the precision of maneuverability prediction, hydrodynamic performances of ship maneuverability are actively researched by many countries to accomplish ship maneuvering simulation in deed. Calculation of ship hydrodynamic performances is very important in accurate prediction of ship maneuverability.In this paper, propeller hydrodynamic performance in open water is calculated by FLUENT software. Thrust coefficient K_t and torque coefficient K_q can be calculated in different advance coefficient. Comparing with calculation data experiment data, it indicates CFD simulation on propeller hydrodynamic performance in open water is feasible.FLUENT and kaermakefu method are used to calculate the hydrodynamic performance of locked propeller in open water respectively.Resistance distribution and transverse force distribution are calculated in different advance coefficient when propeller is locked. Hydrodynamic performance of free rotational propeller in open water is also calculated according to the stable equilibrium theory of rigid rotation.The resistance and critical speed of rotation of propeller in different speed of advance is calculated. It indicates from computational result that speed of rotation in critical condition continuously increases according to the increase of advance coefficient.And in this way, critical transverse force gradually increases as resistance. The rotation direction of free rotational propeller is in accordance with propeller of normal working.Several conditions such as inward or outward propeller is locked and inward or outward propeller freely rotates in which wake effect of ship is considered are simulated, and propeller force is also calculated.Standard K-εturbulent model is used to calculate viscous fluid with free surface in this thesis. Ship resistance in different velocity is calculated. Comparing with experimental result, it is found that the resistance of calculation is less than test result at low velocity, it is opposite at high velocity. After all, the difference is very small and can be negligible. Calculating resistance curve and resistance curve of experiment fit very well. So it can greatly reflect resistance distribution which can testify that it is feasible to calculate viscous flow with CFD method.The wake distribution around ship is further calculated with CFD method including disk of inward propeller and outward propeller.Three dimensional velocity ratio distribution of hull and ship with appendages according to angle is calculated. The radius distribution of average axial velocity, average tangential velocity and average radial velocity is also calculated by CFD method.Average axial velocity, average tangential velocity and average radial velocity of propeller disk at different Fr number are also calculated. It is found that Average axial velocity on the disk of inward propeller and outward propeller increases respectively. It indicates that vary of ship velocity will affect distribution of ship wake.When building up mathematical model, the following factors have been considered: the forces and moment acted on ship, propeller, rudder and interaction between them. Hydrodynamic values which calculated by CFD are set to MMG equation. Runge-kutta method is used to calculate this equation to accomplish ship maneuvering simulation.The results of this thesis can provide the reference guides to study on rapidity and maneuverability of large-scale ship.更多还原