Gas Nuclei Trajectories and Cavitation Inception 



.2 -1.0 -0.8 -0.6 -0.4 -l/it -0.2 0.2 



LONGITUDINAL POSITION 'HALF ULTIMATE BODY WIDTH -x 



Fig. 5 - Gas nuclei trajectories about a two-dimensional 

 half body (h = 0.6 inch; U = 50 fps) 



rate than it does for a^ = 0.4 and 0.58 as the bubble passes into the negative 

 pressure zone in the flow field. 



Lower Critical Bubble Radii 



In Eq. (4), if c* is replaced by the value of Cp ^.^ of the flow field and the 

 definition, w = 2RgpU^/7 is used, then for each value of a^, there is a corre- 

 sponding Rq value. Since Cpn^j^ is the lowest pressure in the flow field, the Kg 

 value thus found is the lowest possible critical bubble radii, Rqj-. For those 

 bubble sizes smaller than Rg^ , all bubbles will remain stable throughout the 

 entire flow field for a specific a^ value. For a two-dimensional half body 

 ^ min ~ -0-587. The value of R*^ for this body is shown by the solid line in 

 Big. 7 as a function of c^. Since the value of c _^.^ for a half body is independ- 

 ent of body size, the R^^ curve will also be independent of body size. Although 

 Cp ^jj^ always occurs on the body surface, it is conceivable that the smaller 

 bubbles will "roll over" the body surface, so they do essentially encounter the 

 minimum pressure in the flow field. 



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