0609 Cloud Characteristics on Collision Center in Cavitating Water Jet

We focus on cavitation erosion in submerged cavitating water jet, especially around jet center part. The appearance of cavitation cloud was examined using a high-speed video camera from two directions, such as side-view and back-view of impinging wall. The high speed video images are estimated by an image analysis based on the frame difference method. The cavitation impacts were measured at the jet center area on the impinging surface together with the cloud appearance. As the result, we found that the erosion of jet center area is caused by the collapse of the existing cloud on the impinging wall.