Some transition and cavitation inception observations on a 1.5 cal ogive

Abstract

Transition observation on a 1. 5 cal ogive were carried out by Schlieren technique of flow visualization up to Re_D of 1.26 x 10^6. Good agreement is found between computed position of transition by Smith method and those observed by Schlieren technique for tunnel velocities greater than 50 fps (Re_D> 7.85 x 10^5). Cavitation under desinent conditions at tunnel velocities of 30 fps and 40 fps was found to occur within the transition region of the boundary layer. At 50 fps good agreement is found between the present value of inception cavitation index, the value of desinent cavitation index measured by Parkin and the negative value of the pressure coefficient at both predicted and observed positions of transition. These observations strongly suggest that cavitation inception is closely related to transition on smooth bodies at supercritical Reynolds numbers.

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