Cavitation, Tensile Strength, and the Surface Films of Gas Nuclei 



DEPTH (FT) 



• THESE TESTS WERE PERFORMED BY TED MADISON, NOW WITH INTERNATIONAL 

 TRANSDUCER CORP., SANTA BARBARA, CALIFORNIA. 



Fig. 1 - Tensile strength of water at 

 different depths in two fresh water lakes 



instead of 39.4 feet. Thus usable tensile strength was found to be available in a 

 natural water. These tests were done during the summer. 



Nuclei should dissolve ideally within seconds to a few minutes but, as shown 

 by tests, often do not. This retards the acquisition of tensile strength, and limits 

 the amount of tensile strength available in the water. This phenomenon is a con- 

 sequence of surface films that gather about the nuclei from small amounts of 

 organic materials dissolved in the water. If surface films did not exist, much 

 higher tensile strengths would be found. 



Various waters tested varied widely in their tendency to form these surface 

 films, as evidenced by variations of more than 100:1 in the dissolving rate of 

 the nuclei contained in the water. Waters that did not produce surface films 

 dissolved nuclei quickly. For example, water from the David Taylor Model 

 Basin's test tunnels acquired tensile strength quickly after being cavitated. 

 Here, one would attribute the lack of surface films to the fact that chlorinated 

 water is used in the tunnels. In comparison, the "prototype" sea water and lake 

 water tested were approximately an order of magnitude slower in dissolving. 

 When heavy organic growths were present in water, much slower dissolving — 

 or none at all — resulted. 



Surface films were deliberately produced about nuclei by dissolving small 

 quantities of hydrocarbons or proteins in water. It was found possible to obtain 



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