Optimisation of a Cavitation Device

The Problem

Hydrodynamic cavitation induced by the acceleration of a fluid causes the local static pressure to drop to the fluid vapour pressure. Vapour bubbles are then instantaneously developed and travel along with the fluid. Once the bubble reaches a higher pressure zone, the vapour bubbles violently collapse, creating high intensity pressure and temperature pulses. This provides a powerful mechanism to break down unwanted elements and is the basis upon which the geometrical features of cavitation units are designed. However, to optimise the geometrical design, one requires some sort of measurement of cavitation.

The Approach

The measurement of cavitation can be obtained from a hydrophone. One of which, was employed in this work. The experimental work then involved a study of the effects of variations in geometry in order to obtain enhanced operational conditions. In order to measure this, a ‘real-time’ monitoring system consisting of a hydrophone, data logger and power spectrum analyser was employed.

The Result

The ‘real-time’ monitoring and control system provided instant measurements of performance by measuring acoustic energy release. This allowed development of a suitable design which increased the frequency of cavitation events 5-fold and the magnitude of pressure pulses 10-fold with no additional energy input.