disturbance velocity, V , are negligibly small, the Bernoulli constant, H , will 

 be: 



Ha = [4- V^ + - + gy 1 (27) 



Then the pressure at an arbitrary point in the fluid can be expressed as: 



p = _ ^ p |v.V - (V^)2 - rV} - pg(y^ - y^^) + p^ (28) 



where V = V + rfie„ + V + V , and the subscript A indicates a point on the same 

 — — w ^ ^ — o 



streamline (or vortex line) where the pressure is computed. The effect of gravity, 

 ~Pg(y ~ y a) ^^ Equation (28) gives rise to a once-per-revolution periodic varia- 

 tion in the pressure in the rotating coordinate system. Since this term does not 

 contribute to the mean pressure and the loading, it is not considered in the pre- 

 sent study. However, this term may be important when cavitation inception is of 

 interest. 



For a uniform onset flow (potential flow) with only an axial component and 

 with no other disturbance than the propeller itself, i.e., the flow condition 

 applicable to all the experimental measurements correlated in this report, the 

 pressure equation becomes even simpler: 



P = - Y^{-'^ ~ ^x ~ ^^"^1 ^ Poo (29) 



where V = V i + rQe„ + V , and p is the known pressure far upstream. In this 

 case, the Bernoulli head is constant everywhere in the fluid since there is no 



vo 



rticity in the flow (see Equation (24)). 



20 



