AUTHOR'S CLOSURE 



The discussers' diversified iDackgrounds and experience in 

 t.hA fields of Physics and Naval Architecture testify in a most 

 striking manner to the interest in the field of cavitation 

 and reflect the need in this field for constant interchange 

 of ideas and information among those concerned with basic mech^ 

 anisms and theory and those ^^/hose ultimate responsibility is 

 the interpretation and application of such information for 

 design purposes o If the point of view taken in TMB Report 712 

 and this supplement and the scheme adopted in the "unification" 

 of the material has helped in even a small way to establish 

 more clearly the bases for such comraunication, then it is 

 felt that the results have more than compensated the effort. 



Before considering the printed discussions, a word of 

 apology to those who presented discussions appears to be in 

 order » The very short time available for preparation of the 

 discussions and the availability of only a preliminary edition 

 placed an extra burden on the discussers and was occasioned 

 by the writer's failure to have the final edition ready in 

 time for examination before the presentation to the Chesapeake 

 Section of the Society of Naval Architects and Marine Engineers 

 on October l8, 1952. The writer is very grateful not only to 

 those who somehow found the time to send written discussions 

 but also to those who presented oral remarks at the meeting. 

 Thus, it should be observed that the printed discussions 

 refer to the preliminary version of the paper and not to the 

 final report, 



Dr, Todd's resume of the cavitation problems facing the 

 Naval Architect is a particularly valuable adjunct to the 

 present paper because is brings out the necessity for more 

 intimate knowledge of the cavitation mechanism and for 

 extension of theoretical results o '-^ith regard to the specific 

 question concerning scaling of propeller experiments, the 

 present methods used at the Taylor Model Basin are not in- 

 compatible with the concepts outlined in this paper and with 

 the conclusions reached by Kermeen and Parkin = I^irthermore, 

 the present TMB practice of using larger models and higher 

 speeds than were formerly used is designed to reach as large 

 values of the Reynolds number as possible with the facilities 

 available. This is particularly important in attempting to 

 obtain flow similarity and, thus, similarity in the pressure 

 distributions. However, the propeller problem is considerably 

 complicated by the differences between the sea water in which 

 the prototype operates and the fresh water in the cavitation 

 tunnel o Crump concluded that to obtain the same critical 

 cavitation numbers in the TMB water tunnels as in his 



