基于DES的舰船空气尾流场特性和旋翼气动特性分析
发布时间：2019-05-24 14:52
【摘要】：舰船上层建筑是由一系列钝体组合而成,当舰船运动或者有风作用时,上层建筑后方会产生湍流尾流场。尾流场中形成了大尺度的流动分离和回流,巨大的速度梯度伴随着不同尺度的涡产生,使得流场十分复杂。舰载直升机具有极高的战术价值,已经成为海军装备的重点发展对象。高度不稳定的舰船尾流场对舰载直升机的操纵产生了严重的威胁,旋翼本身的旋转也会产生复杂的流场,与空气尾流相互作用时会导致其载荷发生变化,进而导致升力发生变化,给飞行员的操作带来了很大的困难,也对飞行的安全造成了影响。本文采用CFD方法对舰船空气尾流场的特性进行了分析研究,突破了雷诺时均方法的局限性,使用分离涡模拟的方法求解了瞬态流场。按照一定频率采样流场数据,得出的平均流场明显比RANS方法的结果更贴近实验数据,证明了此方法的有效性。并且DES方法可以更直观的观察流场的涡特性,便于观察流动分离和再附着等特征。基于DES在舰船空气尾流场求解上的成功应用,又进一步研究了孤立的直升机旋翼流场以及舰船-旋翼耦合流场的特性,分析了舰船对旋翼流场的影响。研究显示旋翼与舰船空气尾流相互影响时,空气尾流场的速度分布、旋翼流场的涡特性、旋翼表面压力分布等等都产生了巨大变化,在宏观上,旋翼产生的升力下降了29.42%。通过本文的研究,证明了DES方法非常适合用于研究舰船空气尾流场,同时也阐明了空气尾流场的基本特征、舰船-旋翼相互作用的复杂性以及直升机旋翼在空气尾流场中性能的变化。
[Abstract]:The ship superstructure is composed of a series of blunt bodies. When the ship moves or has the action of wind, the turbulent wake field will be produced behind the superstructure. Large scale flow separation and reflux are formed in the wake field, and the huge velocity gradient is accompanied by vortexes of different scales, which makes the flow field very complex. Shipborne helicopters have high tactical value and have become the key development object of naval equipment. The highly unstable wake field of the ship poses a serious threat to the maneuvering of the shipborne helicopter, and the rotation of the rotor itself will also produce a complex flow field, which will cause the load to change when interacting with the air wake. Thus, the lift changes, which brings great difficulties to the operation of the pilot, and also affects the safety of the flight. In this paper, CFD method is used to analyze and study the characteristics of ship air wake field, which breaks through the limitation of Reynolds time-averaged method and solves the transient flow field by using the method of separated vortex simulation. According to the flow field data sampled at a certain frequency, the average flow field is obviously closer to the experimental data than that of the RANS method, which proves the effectiveness of the method. The DES method can observe the vortex characteristics of the flow field more intuitively, and it is convenient to observe the characteristics of flow separation and reattachment. Based on the successful application of DES in the solution of ship air wake field, the characteristics of isolated helicopter rotor flow field and ship-rotor coupling flow field are further studied, and the influence of ship on rotor flow field is analyzed. The results show that when the rotor and the ship air wake interact, the velocity distribution of the air wake field, the vortex characteristics of the rotor flow field, the pressure distribution on the rotor surface and so on all have great changes. The lift produced by the rotor decreased by 29.42%. Through the research in this paper, it is proved that the DES method is very suitable for the study of ship air wake field, and the basic characteristics of air wake field are also expounded. The complexity of ship-rotor interaction and the change of helicopter rotor performance in air wake field.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U674.70
本文编号：2484953
[Abstract]:The ship superstructure is composed of a series of blunt bodies. When the ship moves or has the action of wind, the turbulent wake field will be produced behind the superstructure. Large scale flow separation and reflux are formed in the wake field, and the huge velocity gradient is accompanied by vortexes of different scales, which makes the flow field very complex. Shipborne helicopters have high tactical value and have become the key development object of naval equipment. The highly unstable wake field of the ship poses a serious threat to the maneuvering of the shipborne helicopter, and the rotation of the rotor itself will also produce a complex flow field, which will cause the load to change when interacting with the air wake. Thus, the lift changes, which brings great difficulties to the operation of the pilot, and also affects the safety of the flight. In this paper, CFD method is used to analyze and study the characteristics of ship air wake field, which breaks through the limitation of Reynolds time-averaged method and solves the transient flow field by using the method of separated vortex simulation. According to the flow field data sampled at a certain frequency, the average flow field is obviously closer to the experimental data than that of the RANS method, which proves the effectiveness of the method. The DES method can observe the vortex characteristics of the flow field more intuitively, and it is convenient to observe the characteristics of flow separation and reattachment. Based on the successful application of DES in the solution of ship air wake field, the characteristics of isolated helicopter rotor flow field and ship-rotor coupling flow field are further studied, and the influence of ship on rotor flow field is analyzed. The results show that when the rotor and the ship air wake interact, the velocity distribution of the air wake field, the vortex characteristics of the rotor flow field, the pressure distribution on the rotor surface and so on all have great changes. The lift produced by the rotor decreased by 29.42%. Through the research in this paper, it is proved that the DES method is very suitable for the study of ship air wake field, and the basic characteristics of air wake field are also expounded. The complexity of ship-rotor interaction and the change of helicopter rotor performance in air wake field.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U674.70
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