HIGH-SPEED OBSERVATIONS OF THE CAVITATION CLOUD AROUND A HIGH-SPEED SUBMERGED WATER-JET

In this paper, we attempt to clarify the jet structure and the behavio r of severely erosive cavitation clouds around a high-speed submerged water jet, using a high-speed movie camera with a framing rate of ten thousand frames. The effects of the injection pressure and the nozzle geometry on cavitation are also investigated. The experiments are perf ormed with both a free jet and an impinging jet. It is clearly found t hat the cavitation clouds are periodically discharged. The cavitation clouds are also closely related to downstream instability and to the i mpinging erosion.