Accession Number:

ADA225375

Title:

Observations of the Dynamics and Acoustics of Travelling Bubble Cavitation

Descriptive Note:

Final rept. 1986-1990

Corporate Author:

CALIFORNIA INST OF TECH PASADENA DIV OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s):

Report Date:

1990-06-25

Pagination or Media Count:

185.0

Abstract:

Individual travelling cavitation bubbles generated on two axisymmetric headforms were detected using a surface electrode probe. The growth and collapse of the bubbles, almost all of which were quasi-spherical caps moving close to the headform surface, were studied photographically. Although the growth patterns for the two headforms were similar, the collapse mechanisms were quite different. These differences were related to the pressure fields and viscous flow patterns associated with each headform. Measurements of the acoustic impulse generated by the bubble collapse were analyzed and found to correlate with the maximum volume of the bubble for each headform. Numerical solutions of the Rayleigh-Plesset equation were generated for the same flows and compared with the experimental data. The experiments revealed that for smaller bubbles the impulse-volume relationship is determinate, but for larger bubbles the impulse become more uncertain. The theoretical impulse was at least a factor of two greater than the measured impulse, and the impulse-volume relationship was related to the details of the collapse mechanism. Acoustic emission of individual cavitation events was spectrally analyzed and the results were compared with relevant theoretical and emperical predictions. Finally, the cavitation nuclei flux was measured and compared to the cavitation event rate and the bubble maximum size distribution through the use of a simple model. Theses.

Subject Categories:

  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE