PIV法によるレーザー誘起キャビテーションクラウドの二次元流速ベクトル場の観測と計測

抄録

A cloud of bubbles induced by a high-speed submerged water jet shows a collective unsteady motion repeating a process of growth and collapse. It is considered that a high-pressure shock wave is emitted associated with the collapse of the cloud, and such shock wave phenomena have been used in the applications to medical and environmental fields. However, the elementary process of such unsteady behaviors of the cloud and the shock wave phenomena has not been well understood through experimental observations. In this study, we make experimental observations and measurements of two-dimensional velocity fields around the cloud cavitation that is induced by Ho:YAG laser via the fluorescent Particle Image Velocimetry (PIV) method. In particular, based on our previous numerical tests (2), we illustrate the flows of twin vortices that appear around the cloud and move along its interface. Finally, we experimentally clarify the existence and the motion of the twin vortices in the growth and shrink processes of the cloud, from which it follows that the unsteady behavior of the cloud is synchronized with the motion of the twin vortices.