Bernd 



21. Hawke and Alexander, "The Influence of Surface- Active Compounds upon 

 the Diffusion of Gases across the Air-Water Interface," in Ref. 14 



22. Gorter, Ormondt, and Dom, "The Spreading of Ovalbumin," Proc. K. Acad. 

 Wetensch, Amsterdam 35 (1932) 



23. Stein and Moore, "The Chemical Structure of Proteins," The Scientific 

 American 204, Feb. 1961 



24. 'International Encyclopedia of Chemical Science," Van Nostrand, 1964 



25. Bohn, "Schalldruckverlauf und Spectrum bei der Schwingungskavitation, " 

 Acustica 7 (1957) 



26. Hsieh and Plesset, "Theory of Rectified Diffusion of Mass into Gas Bubbles," 

 J. Acoust. Soc. Amer. 33(No. 2), 1961 



27. Briggs, "Limiting Negative Pressure of Water," J. Appl. Phys. 21:721 (1950) 



♦ « ♦ 



DISCUSSION 



C.-A. Johnsson 



Swedish State Shipbuilding Experimental Tank 



Goteborg, Sweden 



In connection with this extremely interesting paper I think it might be rele- 

 vant to summarize briefly the results of some comparative tests which have 

 been performed as part of the work of the Cavitation Committee of the 11th In- 

 ternational Towing Tank Conference (ITTC). These tests studied primarily the 

 cavitation inception on a head of a body of revolution. Results were obtained 

 from 14 establishments including results from 13 different bodies tested in 17 

 different cavitation tunnels. 



The results for gas content ratio a/a^ = 0.6, corrected for wall influence 

 on water speed and cavitation number, are shown in Fig. Dl. You can see that 

 there is a considerable dispersion around the value of the pressure minimum 

 for the body, which corresponds to a = 0.6. Most of the tunnels have inception 

 values below 0.6, indicating negative cavitation pressures, but there are two 

 tunnels having high positive values. The pressure minimum being known in this 

 case, an approximate calculation of the cavitation pressures can be made. The 

 resulting pressures are shown in Fig. D2 together with results of measurements 

 of cavitation pressures in nozzles, reported elsewhere. 



Some of the differences in cavitation pressure, shown here, are probably 

 due to differences in technique, body size, height of the tunnels and so on, 



108 



