Experimental Study of the Shock Generation at the Collapse of Cavitation Bubble

Abstract

Using a photoelastic apparatus or Schlieren interferometer, we experimentally studied the mechanism of the impulsive force generation by a spark-induced cavitation bubble, collapsing near the solid boundary. The experimental results indicate that the cause of the impulsive force is classified by the parameter l, where l= (maximum bubble center distance from the solid boundary) / (maximum bubble radius). In case of l&gnE;1.35, the shock waves are dominant and in case of l<1.35, the water microjet impingement is the main cause of the impulsive force. In a special case (l&lnE;1.24>), both the shock waves and the water microjet are supposed to impact against the solid boundary. Even when an asymmetrically collapsing bubble rebounds, the shock waves are observed.