水下航行体在侧方来流作用下超空化现象研究

Investigation of the Influence of Lateral Flow on the Supercavitation for Underwater Vehicle

海底环境复杂多变,水下超空泡航行体运动过程中,必然会受到侧面来流的冲击,对航行体的体外超空泡产生影响。但目前针对此现象的研究较少,同时侧方流的引入通常会导致数值不稳定引起计算发散,为解决数值发散问题并研究非定常侧方来流对超空化现象的影响规律,基于开源CFD软件OpenFOAM,通过自定义侧方流源项,对相变求解器进行重新编译,结合SST K-w湍流模型.Schnerr-Sauer相变模型、流体体积分数多相流模型构建侧方流作用下的超空化流动数值模型。研究不同侧方流强度下的流场空化情况,超空泡形态变化规律以及航行体阻力变化情况。研究结果显示:侧方流对超空泡的影响程度是由对流速度即模型体运动速度、侧方流强度等共同决定的。相同侧方流速度下,对流速度越大,超空泡受冲击越弱,航行体阻力变化较小。侧方流速度与对流速度相差较大时,对超空泡形态及航行体阻力影响较小,随着侧方流加强,超空泡会发生变形乃至脱落,航行体阻力大幅增加。

The submarine environment is complex and ever-changing. During the movement of underwater supercavitation vehicles, it is bound to be affected by the lateral flow and affect the supercavity of the vehicle. The introduction of lateral flow usually leads to numerical instability and causes the calculation to diverge. In order to solve the problem of numerical divergence and study the influence of unsteady lateral flow on the phenomenon of supercavitation, based on open source CFD code OpenFOAM, the phase change solver was recompiled by customizing the lateral flow source term. Combined with the SST K-w turbulence model, the Schnerr-Sauer phase transition model, and the fluid volume fraction multiphase flow model, the cavitation flow numerical model was build. The flow field cavitation under different lateral flow intensities, the variation of supercavity morphology and the change of the resistance of the voyage body were studied. The results show that the influence of lateral flow on the supercavity is determined by the convection velocity, ie, the velocity of the model body and the strength of the lateral flow. Under the same lateral velocity, the higher the convection velocity is, the weaker the impact on supercavity is, while the variation of the body resistance of the voyage is smaller. When the lateral flow velocity is much less than the convection velocity, it has little effect on the shape of the supercavity and the resistance of the voyage body. As the lateral flow strengthens, the supercavity will deform even off, and the body resistance increases significantly.