subcavitating propeller, an airfoil with the same pressure distribution and the same 

 source distribution has been used instead of a supercavitating cascade. When v 

 is represented as the angle of the two-dimensional velocity with respect to the nose- 

 tail line and v„ is represented as the angle of the three-dimensional velocity a 

 with respect to the geometric advance angle 3» then by taking a single term in the 

 summation of Equation (39) , a will be interpreted as the corrected angle of attack 



of the nose-tail line with respect to ft, and c will indicate a camber correction of 



6 ° 



the two-dimensional foil. In the general case the angle of attack will be 



1 2 2 

 a + ~ c +~ c + ... (40) 



o I J 



and the camber correction due to^a. x has to be considered in addition to the 



correction due to c . The optimum number of terms in Equation (39) depends upon the 

 o 



number of collocation terms. 



FORCES ON THE BLADE 

 As in the two-dimensional supercavitating flow, lift and drag should be evalu- 

 ated by integrating pressure on the blade surface. The section drag in the direction 

 of the nose-tail line is 



1 

 C D - C \ (P+C) V 3n dx + \ C DV E C DC + 1 C DV (41) 



v dx = (42) 



3n 



where C is the friction drag, which is the same as C for the subcavitating case. 

 From the Kutta-Joukowsky theorem, Equation (22), 



2G V l 

 P + o = - — — 

 v V V 



s s 



18 



