19 



1.2 



Uo. 



^^^ 



-1 



T 



T 

 1 





/ 



"^^-1 





/ 



1.0 







/ 



^ 







/ 











Linearized--,^ 



y^ 



8 0.8 



3 







/ 



y 







\ 



^ / 





=1- 



CJ 



0.6 







/ / 



/ 









/ ^ 







0.4 

 02 





// 





-Exact 















/ 













/ 





15 deg 







0.1 0.2 0.3 0.4 



Wedge Halt Angle -;; 



Figure 5 - Cavity Drag Coefficients for 



Wedge Profiles at Zero Cavitation 



Number 



(After Tulin, Reference 34) 



0.04 0.08 0.12 0.16 0.20 0.24 



Cavitation Number o- 



Figure 6 - Cavity Length as a Function of 

 Cavitation Number for a 30-Degr.ee Wedge 



(After. Tulin, Reference 34) 



W. Tliomson (Lord Kelvin).^ ^ Interest in these results extend beyond their intrinsic content 

 since such oscillations may lead to vibrations of the propeller blades. Actual investigations 

 of such interactions remain to be carried out, however. 



A REMARK ON THE DRAG OF CAVITATING BODIES 



Although the drag of bodies with fixed points of separation of the cavity (flat plates, 

 discs, cones) can evidently be approximated by an equation of the form (see Reference 3) 



C^{a) = C^(0) (1 + a) 



where C jXa) is the drag coefficient for cavitation number a, this does not appear to be the 

 case in actual flows for bodies with longitudinal curvature. The linear increase of drag with 

 cavitation number shown in experiments is in good agreement with theory, but the slope of 

 the curve evidently depends on the form. For results available so fat, it appears that the 

 drag can be closely approximated by the formula 



Cn(a) = (7n(0) (1 +cta) 



'D 



