Oscillating -bladed Propellers 



Fig. 



3 - Fitting of propeller 2133 

 in the cavitation tunnel 



to determine the cavitation patterns for given values of J and a. At this effect, 

 three values of J were selected: j = 0.65, corresponding to normal conditions 

 of loading; J = 0.50 and J = 0.75, corresponding to overloaded and underloaded 

 conditions. 



EXPERIMENTAL RESULTS 



Fixed- Bladed Propeller (7=0) 



Types of Cavitation Observed— Figures 5a through 8a, and Fig. 10a show 

 the cavitation patterns for different values of d , J, and a. According to the 

 value of J, six different types of cavitation can be observed: 



1. Bubbles on the back near the hub 



2. Bubbles on the back for x > 0.6 at the inception . , 



3. Sheet on the leading edge prolonged by a tip vortex 



4. Tip vortex : 



5. Hub vortex 



6. Sheet on the face leading edge near the hub. 



15' 



Figures 4a and 9a give the inception curves (^ versus J) for d = 10° and 

 respectively. 



Influence of the Longitude (p — As expected from the analysis made in the 

 section on variation of incidence on the blade element due to inclination of the 

 shaft, the longitude has a considerable influence on the back and face cavitations. 



1505 



