Propeller Design 



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02 03 0/i 05 0./ 



I. 5 



Fig. 3a - Curves of incipient cavitation phe- 

 nomena of screw of the B 5-75 series 



the various characteristic curves for the onset of the different types of cavita- 

 tion have been indicated: bubble cavitation midchord (bmc), sheet cavitation at 

 the suction side (ssc), sheet cavitation at the pressure side (psc) and the visible 

 tip vortex (tvc). 



In Fig. 4, a part of the large N.S.M.B. cavitation tunnel is shown schemati- 

 cally with a measuring arrangement designed for the investigation of the effect 

 of cavitation on the propeller-induced vibratory forces. 



In Fig. 5, pressure distributions of a two-dimensional screw blade profile 

 have been reproduced for various cavitation numbers at constant angle of inci- 

 dence. From this figure, the effect of cavitation on the under-pressure peak at 

 the leading edge is clear; cavitation reduces this peak strongly. 



1578 



