基于高速摄影的直角壁面附近柱形空泡动力学行为研究

RESEARCH ON DYNAMICS OF THE CYLINDRICAL CAVITATION BUBBLE NEAR A RIGHT-ANGLE WALL BASED ON HIGH-SPEED PHOTOGRAPHY

  • 摘要: 本文基于高速摄影实验,对直角壁面附近的柱形空泡动力学行为进行了研究。空泡由激光聚焦诱导产生,形成于具有较小间距的两片平行玻璃板之间的液体环境中,从而具有了较为明显的柱形特征。通过改变柱形空泡距离直角壁面顶点的无量纲距离l*和位置角度θ,分别探究了对称和非对称处柱形空泡的完整溃灭行为及变化趋势,并揭示了柱形空泡与直角壁面的相对位置对柱形空泡泡壁变形、形心移动距离及方向等泡动力学特性的影响。研究发现:在第一周期溃灭过程中,柱形空泡远离直角壁面一侧的泡壁将会出现凹陷,并且逐渐发展直至将柱形空泡分为两部分;当空泡位于对称位置时,随着无量纲距离l*的逐渐增大,柱形空泡表面凹陷程度逐渐减弱,且空泡在溃灭阶段的形心移动距离逐渐减小;当空泡位于非对称位置时,随着空泡位置角度θ的减小(对θ < 45°的情况而言),柱形空泡形心的移动方向由指向壁面顶点逐渐变为指向下壁面。

     

    Abstract: The dynamics of cylindrical cavitation bubble near a right-angle wall are investigated based on the high-speed photography experiment. The cavitation bubble is induced by laser focusing and formed in the liquid environment between two parallel glass plates with a small spacing, thus having obvious cylindrical characteristics. By changing the dimensionless distance l* between the cylindrical cavitation bubble and the right-angle wall vertex, and the position angle θ, the complete collapse behaviors and variation trends of the cylindrical cavitation bubble at the symmetric and asymmetric positions are investigated, respectively. The influence of the relative position between the cylindrical cavitation bubble and the right-angle wall on the bubble dynamics, such as the deformation of the cylindrical cavitation bubble wall, the movement distance and direction of the bubble centroid are revealed. The research results are as follows: During the collapse stage of the first period, the bubble surface on the side of the cylindrical cavitation bubble away from the wall will appear concavity, and gradually develop until the cylindrical cavitation bubble is divided into two parts. When the bubble is located at symmetrical positions, as the dimensionless distance l* increases, the concave degree of the bubble surface is gradually weakened, and the moving distance of the bubble centroid during the collapse stage is gradually reduced. When the bubble is located at asymmetric positions, as the position angle θ decreases (for the situation of θ < 45°), the moving direction of the bubble centroid gradually changes from pointing to the vertex of the angled wall to pointing to the lower wall.

     

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