水下航行体超声速射流与尾空泡耦合作用初期的流场特性

针对航行体水下垂直发射过程，利用固体火箭发动机在尾空泡内点火实现有控运动，是保证复杂因素干扰下航行体弹道稳定的重要手段。基于流体体积模型、标准k-ε湍流模型和动网格技术，通过求解雷诺时均Navier-Stokes方程，获得超声速射流与尾空泡耦合作用初期的流场特性及其演化规律。结果表明：航行体出筒后形成的半椭球状附体尾空泡，在超声速射流作用下逐渐演变成葫芦状，其内部流动受到破坏后进行重构，没有形成回射流现象；超声速射流完全受限在尾空泡内发展，射流流动主要位于径向尺寸和喷管出口直径相当的核心区内，在射流卷吸作用和空泡界面影响下，尾空泡内相继出现了一次涡环和二次涡环结构；航行体尾部与筒口中心位置压力呈现宽幅振荡特征，最大振幅约为发射水深压力的1.2倍，致使射流结构和航行体受到的实际总推力出现大幅度振荡变化。

Flow Field Characteristics of the Early-stage Coupling Interaction between Supersonic Jet and Tail Cavity of Underwater Vehicles

For the vertical launch of underwater vehicles, igniting the solid rocket engine in the tail cavity to control movements is an essential approach to stabilize the trajectory under the interference of complex factors. Based on the fluid volume model, standard k-ε turbulence model and dynamic mesh method, and by solving Reynolds-averaged Navier-Stokes equations, the flow field characteristics and evolution law of the coupling effect between supersonic jet and tail cavity in the early stage are studied. The results show that the semi-ellipsoidal appendage tail cavity formed after an underwater vehicle leaves the launch tube gradually evolves into a gourd-shaped cavity due to the supersonic jet effect. The internal flow is reconstructed after damage without forming a reentrant jet flow. The supersonic jet flow is completely limited in the tail cavity, and the radial size of the jet flow is basically equal to the diameter of the nozzle outlet. Primary and secondary vortex rings appear successively in the tail cavity due to jet cogging and the effect of the cavity surface, while pressures at the tail of the underwater vehicle and the center of the launch tube exit show wide-amplitude oscillations. The maximum amplitude is about 1.2 times of the water pressure at the launching spot, causing significant variance in the jet structure and engine thrust.