纵平面回转运动通气超空泡形态及压力特性

通气超空泡技术是提高水下航行体运动速度的一种新兴技术,为研究通气超空泡在航行体纵平面回转过程中的机动性问题,本研究基于有限体积法,采用VOF多相流模型和RNG k-ε湍流模型,利用数值模拟软件Fluent建立了非定常通气超空泡流动的三维计算模型.通过求解多相混合物的雷诺平均Navier-Stokes方程,分析了空化器模型纵平面回转运动过程的非定常多相流动特性,得到了纵平面回转运动条件下通气超空泡的形态变化及其与空泡周围压力分布的关系.计算结果表明:通气超空泡在回转运动过程中受到离心力作用而产生弯曲变形,空泡轴线与航行体运动轨道有逐渐重合的趋势;向下回转时空泡最大直径逐渐减小,向上回转时最大直径逐渐增大;相较于向上回转运动,纵平面回转半径对向下回转运动的空泡形态存在较大影响,且空泡尾部闭合位置的偏转方向不一致,向下回转时空泡尾部发生外漂,向上小角度回转时空泡尾部发生内漂;由于离心力以及空泡轴向的逆压梯度限制,向上回转过程空泡长细比显著增大,向下回转过程空泡长细比缓慢减小.

The shape and pressure characteristics of ventilated supercavity in longitudinal plane rotation motion

Ventilated supercavity technology is an emerging technology that can improve the velocity of underwater vehicle. In order to study the maneuverability of ventilated supercavity in longitudinal plane rotation motion of the vehicle, based on the finite volume method, a three-dimensional computational model of unsteady ventilated supercavity flow was established by using VOF multiphase flow model and RNG k-e turbulence model and utilizing the numerical simulation software Fluent. By solving the Reynolds averaged Navier-Stokes equation of multiphase mixtures, the unsteady multiphase flow characteristics of the cavitator model in longitudinal plane rotation motion were analyzed. The morphological changes of the ventilated supercavity and the relationship with the pressure distribution around the supercavity were obtained under the rotating motion of the longitudinal plane. The calculation results show that the ventilated supercavity was flexed by centrifugal force during the rotary motion, and the axis of the supercavity was gradually coincident with the motion track of the vehicle. The maximum radius of the supercavity gradually decreased when it rotated downward and gradually increased when it rotated upward, and the radius of rotation had a great influence on the shape of the supercavity in the downward rotating motion. In addition, the deflection direction of the closed position of the cavity tail was different. When the bubble tail rotated downward, it drifted outward, and when the bubble tail rotated upward at a small angle, it drifted inward. Due to the centrifugal force and the reverse pressure gradient in the axial direction of the supercavity, the slenderness ratio increased significantly during the upward rotation and decreased slowly in the downward rotation process.