【作者】 徐琴华；

【导师】 朱卫兵；

【作者基本信息】 哈尔滨工程大学 ， 航空宇航推进理论与工程， 2007， 硕士

【摘要】 水下发射导弹具有隐蔽性和可移动性两大突出的优点，但同时也涉及极为复杂的物理过程。其中以导弹发动机水下点火初期的非定常过程为最甚。本文采用数值模拟方法，对导弹在水下点火发射燃气射流初期这一非定常过程进行了研究。导弹(发动机)在水下点火以后，从燃烧室产生的燃气流经喷管喷入水环境中，会在导弹尾部形成一个燃气泡。本文通过对复杂物理模型的简化，采用计算流体力学软件FLUNET所提供的VOF方法对气水界面进行追踪。建立了非定常条件下二维轴对称燃气射流的数学模型，运用有限容积法和瞬态SIMPLE计算式，来模拟整个气水流场的形态。在时间步进求解的过程中，计算了非定常状态各个时刻的气流场和水流场的参数分布，得到了燃气泡的成长变化过程、激波运动和激波面形状。本文还考虑了喷管入口压力上升速率和发射深度对整个流场的影响，给出了不同情况下流场参数和燃气泡的发展过程，并通过对气泡形状、激波位置和激波面形状的比较，得到了不同情况下的流场变化规律：随着压力上升速率的增加，燃气泡和激波形状发展速度加快，激波位置迁移的也快；随着发射深度的增加，燃气泡形状变得更为细长。更多还原

【Abstract】 Underwater launching missile has the advantages of invisibility and removability. But simultaneously it also involves the extremely complex physical process, from which the time-dependent ignition process of an underwater missile is most. In this paper, the time-dependent ignition process of gas jet for launch underwater was studied by means of numerical simulation.After the ignition of an underwater missile (engine), the exhausted gas from combustion chamber would flow along the nozzle, jet to water and form a transient bubble at the afterbody of missile, which makes profound influence on the ballistics properties. In the paper, with the simple physical model, the interface between gas and water was traced by VOF method which was from calculated hydrodynamic (CFD) software FLUENT. And based on the two-dimension axis symmetry non-constant flowing state of jet flow, the paper has simulated the modality of both gas and water flow field by applying the infinite volume method and simple computing program. During the time-stepping, the distribution of physical parameters, the bubble shape, the shock motion and the shock shape at each time were figured out.In this paper, the parameter and the development of bubble have been obtained for cases at different ascent rates of pressure at the entrance of nozzle and different launching depths. According the numerical results, compared the parameters such as the shape of bubble, the shock motion and the shock shape at different case, it was concluded that the development of bubble and shock would be more rapid as the ascent rate of pressure increased and the bubble would be more spindly as the depths increased.更多还原