2001 年 67 巻 656 号 p. 896-902
The collapsing behavior of bubble clouds in cavitating counter jets was investigated to expect the extension of collapsing area and increase in impulsive pressure. We carefully observed the aspects of cavitation clouds with the high-speed video and analyzed such characteristics of cavitation noise as acoustic power and spectrum based on the cavitation noise measured around the jet. It was found that the magnitude of bubble clouds around the impingjng area depends on the distance between two nozzles. The clouds expand more widely in a case of the standoff distance xs/d=70, where xs is the half distance between two nozzles, under the test condition of injection pressure PI=30 MPa. And it was also found that string-like bubbles exist within the impinging area, which result in relatively high impulsive pressure in the case of xs/d=190. The acoustic power calculated based on high frequency components of noise also shows relatively high values when xs/d=70.