INTRODUCTION 



In recent years, requirements in the design of hydrodynamic systems 

 for use at increasingly greater speeds and lower pressures have emphasized the 

 problem of prevention of cavitation and its associated damage to materials, 

 losses in efficiency and objectionable noise, as well as increase of drag of 

 submerged bodies with cavitation onset. Although many questions remain which 

 must be answered before the mechanism of cavitation phenomena can be more com- 

 pletely understood, much progress has been made toward rational descriptions 

 of the processes in cavitating systems. This work includes not only the hydro- 

 dynamics of flows with both liquid and gas or vapor phases, but also the 

 physical-chemistry of such two-phase flows in relation to the formation, col- 

 lapse, and maintenance of cavities. It is the purpose of this discussion to 

 present a brief survey of the available information that is not only of the- 

 oretical interest but of interest to the design engineer and naval architect 

 for technical application. At the same time, those areas* in which much work 

 remains to be done will be apparent. No attempt will be made to be exhaustive 

 and, of necessity, the material discussed will reflect the immediate interests 

 of the writer. However, it is hoped that, although little detail is given on 

 several aspects of the cavitation problem, no significant portions have been 

 overlooked. An attempt will also be made to point out the various systems 

 which may be characterized as cavitating-systems from either the hydrodynam- 

 ical or the physical-chemical point of view or both. 



The possibility of cavitation in hydraulic machines was recognized 

 as long ago as 175^ in a memoir of Euler in connection with the theory of 

 turbines. 1 However, significant work on cavitation in engineering applica- 

 tions can probably be dated from the experiments of Reynolds reported in 1 8Q4- 2 

 and the observations of Thornycroft and Barnaby. 3 ' 4 The latter works on screw 

 propellers were especially of importance in the identification of cavitation 

 as a major problem in the field of naval architecture, and gave impetus to 

 investigations of the effects of cavitation on drag and efficiency not only on 

 propellers but other ships' appendages as well. 



A resume of some of the early work of this century is given in Ref- 

 erence 5) and a rather complete bibliography of cavitation researches espec- 

 ially of interest to the hydraulic engineer and naval architect is given in 

 Reference 6. A survey of the cavitation problems considered of importance in 

 hydraulic machines and large hydraulic structures will be found in Reference 

 7- 



References are listed on page 63 of this report. 



