Cavitation experimental techniques

Methods which would produce a surface morphology dependent on the local hardness might, however, be applicable. One such experimental technique uses ultrasonic cavitation to detect hardness differences (18). The sample and an ultrasonic transducer placed near the surface to be studied are immersed in a liquid. 

Cavitation in an under-cooled liquid can cause nucleation, and this probably accounts for a number of the above reported effects. Hunt and Jackson (1966) demonstrated, by a novel experimental technique, that nueleation occurs when a cavity collapses rather than when it expands. Very high pressures ( 10 bar) can be generated by the collapse of a cavity the change in pressure lowers the crystallization temperature of the liquid and nucleation results. It is even suggested that nucleation caused by seratehing the side of the containing vessel could be the result of cavitation effects. 

An ultrasonic technique was applied to AGMD to enhance the permeability for the concentration of various aqueous solutions. In this study, an ultrasonic stimulation of resonance frequency of 20 kHz and power up to 90 W was applied to a flat-plate AGMD system of 1 p,m PTFE membrane with a temperamre difference of 55°C. A 200% improvement in the transmembrane flux was observed with an ultrasonic intensity of 5 W cm . Experimental investigation of the basic mechanism of ultrasonic enhancement of AGMD suggests that, for a continuous ultrasonic stimulation the dominating mechanisms are microstreaming and cavitation [70,130]. 

Cavhalien Erosion Testbigi When testing materials for their cavitation erosion resistance, there is no laboratory experimental equipment that simulates the total situation fen- a real structural component exposed to cavitating liquids. However, a numbs of laboratory techniques and procedures can be used to, at least reasonably, rank a series of selected materials on the... 

---