transition) for a range of amplification levels. Values of the level 



7 13 9 



chosen range from e (Arakeri 1975b) to e (Huang and Hannan 1975) with e 



as the original value chosen by Smith. Many such transition estimates have 

 now been made, e.g., on bodies of interest in naval hydrodynamics (Kaups 

 1974 and Power 1977), but Arakeri (1973) was evidently among the first to 

 apply this idea to cavitation inception. Calculations were made of the 

 pressure coefficient at transition fusing the amplification level of e ) , 

 and the results so obtained were compared with the desinent cavitation ob- 

 servations of Parkin and Holl (1953) on a 1.5-cal ogive. These results, 

 reproduced in Figure 17, are extremely suggestive. Later, it was possible 

 to measure surface pressure fluctuations at a point on this same body 

 (Figure 18) to reveal large peak pressure fluctuations at the site of 

 transition. The spectra of these same fluctuations were compared with 

 the expectations of the linear stability calculations (Figure 19) to 

 show, remarkably, that the most sensitive frequencies according to the 

 theory were actually observed. So it was with some anticipation that 

 spark schlieren photographs were taken of this body (Figure 20) . These 

 appeared to reveal cavitation inception at the observed position of what 

 are interpreted to be boundary layer transition disturbances (Arakeri and 

 Acosta 1974). 



More recent work of McCarthy et al. (1976) has shown a similar 

 favorable agreement of surface (hot film) fluctuation frequency response 

 with the estimates made from linear stability calculations. Perhaps then 

 the plausibility of cavitation inception correlations with the location of 

 transition, i.e., a relation such as Equation (11), is heightened with this 

 closer association of transition as a site of fairly large disturbances. 

 Direct confirmation of transition-connected cavitation on small bodies 

 having deeper minimum pressures present some experimental problems because 

 of the small range of speed and pressure variables available for cavitation 

 index and Reynolds number excursions. One such body that has proved useful 

 in laboratory comparisons is the modified ellipsoidal flat faced head form 

 similar to the ITTC body except with a deeper pressure minimum. It was 

 used in cavitation studies first by Peterson (1969) and then later by 



33 



