Towards the concepts of hydrodynamic cavition control

Abstract

A careful study of the existing literature available in the field of cavitation, reveals the potential of ultrasonics to be used as a tool for controlling and, if possible, eliminating hydrodynamic cavitation through the manipulation of nuclei size present in a certain flow. A glass venturi is talien to be an ideal device to study the cavitation phenomenon at its throat and its potential control. A piezoelectric transducer, driven at crystal resonant frequency, is used to generate acoustic pressure field and is termed as 慤ltrasonic Nuclei Manipulator (UNM)�. Electrolysis bubbles serve as artificial nuclei to produce travelling bubble cavitation at the venturi throat in the absence of UNM but this cavitation is co m p letely elim inated when UNM is operative. This is made possible because the nuclei, which pass through the acoustic field first, cavitate, collapse violently and perhaps fragment and go into dissolution before reaching the venturi throat. Thus, the potential nuclei for travelling bubble cavitation at the venturi throat seem to be systematically destroyed through acoustic cavitation near the UNM. From the solution to the bubble dynamics equation, it has been shown that the potential energy of a bubble at its maximum radius due to acoustic field is negligible compared to that for the hydrodynamic field. Hence, even though, the presently achieved control of hydrodynamic m a cro cavitation is at the expense of acoustic m icro cavitation, it can be still considered to be a significant gain. These are some of the first results in this direction.