06THRESHOLDS OF ACOUSTIC CAVITATION.
Abstract
27Cavitation thresholds in water were measured as a function of frequency, dissolved gas, ambient pressure, and suspended particle size. The apparatus used comprises a two-liter volume of water enclosed by a spherical glass shell driven at its radially symmetric resonance frequencies by eight multiresonant piezoelectric transducers. Large acoustic pressures can be produced, ranging from 10 bars at 27 kc/s to 200 bars at 1.16 Mc/s. The threshold data can be divided into three regions. In region A, defined by f < 200 kc/s, acoustic pressure, P sub a < 3 bars, and air saturation pressure P sub s > 600 mm Hg, small air bubbles grow by rectified diffusion and stabilize at the pressure nodes. In region B, defined by f < 200 kc/s, P sub a > 3 bars, and P sub s < 500 mm Hg, transient cavities are formed that can be detected visually and aurally. In region C, f > 200 kc/s, P sub a > 3 bars, for any value of P sub s, transient cavities are formed, but their presence can be detected only acoustically. Experiments on cavitation at pressures larger than the threshold indicate that only a finite number of cavitation events can be produced in a given sample of water when it is isolated from contamination by airborne motes. In this way water can be strengthened by a factor of at least 8 by repeat cavitation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 11, 1964
- Accession Number
- AD0600839
Entities
People
- James E. Barger
Organizations
- Harvard University