MECHANISM OF TRANSFORMATION AND CONCENTRATION TO IMPULSIVE ENERGY FROM FLOW DYNAMIC ENERGY DUE TO CAVITATION

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The occurrence mechanism and high impact due to energy concentration due to cavitation are investigated experimentally and numerically from viewpoints of control and prediction of occurrence point and impact strength, especially, about such points as high impact mechanism of vortex cavitation, cavity collapsing behavior and erosion mechanism near solid wall as well as in high pressure field, vibratory cavitation with highly erosive characters and process of energy concentration due to cavitation bubbles.1. The characteristics of cavitation inception were investigated in an axial-symmetrical convergent-divergent nozzle of a Ventuli-type through computer simulation and experiments to make clear the tensile strength of water. 2. For separated vortex cavitation in an inner-flow type of axi-symmetrical channel such as a cylindrical orifice, we can observe a reentrant flow and a shedding of cloud cavitation toward the downstream direction of vortex cavity. 3. The characteristics of cavitatio … More n impacts of separated-vortex-type cavitation in a two-dimensional. Convergent-divergent channel were examined to measure strong impacts especially at the collapse of shedding vortex cavity. 4. The relationship of cavitation bubble behavior with cavitation impacts and erosion was discussed about an alternate shedding-type vortex cavitation caused behind a circular or triangular cylindrical body. The alternate shedding vortex cavitation shows a similar manner to the cloud-like cavitation. 5. A study of cavitation impact was made under the flow condition like an actual flow in a vibratory apparatus and a butterfly valve. The results show that the interference is important on the occurrence of high impact between neighboring bubbles and between the pressure field and the bubble collapse. 6. The propagation phenomenon of pressure wave was examined to make clear the cause of bubble collapse using an ultra-high speed video camera. The bubble collapse was caused in a chain-reaction manner through the propagation of pressure Wave. Less