ABSTRACT 



This report is intended to bring up to date the discussions of TMB Report 

 712 which summarized briefly the status of cavitation problems up to 1950. An 

 attempt has been made to present a more unified outline of the various cavitation 

 processes and to indicate, approximately, the progress on the various topics in 

 this outline. Thus, the earlier discussions of the role of turbulence and of bound- 

 ary layer effects in inception are extended. Some recent work on scale effects in 

 inception is reviewed and some further thoughts on the influence of nuclei content 

 are presented. Recent results of theoretical analysis by various writers on tran- 

 sient cavities including the effects of compressibility and viscosity are briefly 

 mentioned. Further remarks are included on steady-state cavities in real liquids, 

 and recent theoretical wor';s on this type of cavitation are cited. In particular, 

 mention is made of a recent linearized theory by Tulin, which will be of consider- 

 able interest for technical applications. Some recent observations on the drag of 

 cavitating bodies are summarized. Finally, it is observed that perhaps the great- 

 est progress in this field in recent years has been in the recognition and more 

 clear definition of the problems requiring investigation. 



INTRODUCTION 



Although the significance of cavitation phenomena in technical applications has been 

 clearly recognized for many years, investigations of the various aspects were, until recent 

 years, rather limited. In general, earlier researches were restricted to rather isolated problems 

 with little evidence of recognition of the relationships between cavitation and other hydrody- 

 namic phenomena or even between the various types of cavitation. However, modern require- 

 ments in the design of hydrodynamic systems for use at increasingly greater speeds, higher 

 temperatures, and lower pressures have emphasized the need for prevention of cavitation and 

 the associated damage to materials, objectionable noise and induced vibration, losses in 

 efficiency and increase in drag with cavitation onset. Moreover, there has been increasing 

 interest in the design of systems in which normal operation occurs under fully cavitating con- 

 ditions. These problems require a clear understanding of the physical and thermodynamical 

 processes involved and not merely the assembling of systematic, empirical data; the phenomena 

 are such that without this understanding even seemingly straightforward tests may be invalid 

 or subject to misinterpretation when attempting to apply these data. As a result of these re- 

 quirements and realizations, there has been within the past ten years, a significant increase 

 in research activities on the mechanics of cavitation and in the analytic descriptions of the 

 various types of cavitation. 



In addition to these motivations for cavitation research, the use of cavitpted systems 

 for accelerating chemical processes has been of interest for some years, and more recently, 



