Accession Number:

ADA114234

Title:

Cavitation Inception in Separated Flows.

Descriptive Note:

Technical rept.,

Corporate Author:

CALIFORNIA INST OF TECH PASADENA

Personal Author(s):

Report Date:

1981-12-01

Pagination or Media Count:

286.0

Abstract:

The phenomenon of cavitation was studied on four axisymmetric bodies whose boundary layers underwent a laminar separation and a subsequent turbulent reattachment. The conditions for cavitation inception and desinence were determined and several holograms were recorded just prior to and at the onset of cavitation. The population of microbubbles and the nature of the subsequent development of visible cavitation was determined from the reconstructed image. Cavitation inception occurred in the turbulent shear layer downstream of the transition region. When the separation zone was large the inception region was located within the most developed section of the mixing layer but upstream of the reattachment zone. When the separation region was small inception occurred close to the reattachment zone but still detached from the body surface. A comparison between the surface minimum pressure and the cavitation inception indices also indicated that inception could not occur near the surface of the bodies having a large separation region. The appearance of visible cavities was preceded by the appearance of a cluster of microbubbles only in the cavitation inception region. The nuclei population in the other sections of the flow field remained fairly uniform. This observation supports the assumption that cavitation is initiated from microscopic free stream nuclei.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE