Cavitation Inception Observations on Six Axisymmetric Headforms

Cavitation inception observations on a series of axisymmetric headforms were made in the DTNSRDC 36-in. water tunnel. Cavitation inception observed on headforms with natural flow transition is characterized by the growth and collapse of the individual undissolved air bubbles in the water when traveling through the low pressure regions of flow transition. Cavitation inception observed on headforms with laminar separation is characterized by an attached band or bubble-ring cavitation starting at the separation point. The traveling bubble type cavitation inception is significantly affected by the microbubble population. However, the effect of total air content and size distribution of the bubbles on attached cavitation inception is less pronounced. Attached spot or ring/band cavitation never occur at the location of minimum static pressure but are observed first in the regions of natural flow transition or laminar separation.