Measurements of the Transverse Velocity of a Separating Turbulent Boundary Layer.
Abstract
The problem of turbulent boundary layer separation due to an adverse pressure gradient is an old but still important problem in many fluid flow devices. Until recent years little quantitative experimental information was available on the flow structure downstream of separation because of the lack of proper instrumentation. The directionally-sensitive laser anemometer now provides the ability to accurately measure the instantaneous flow direction and magnitude. Simpson, Chew, and Shivaprasad (1980) presented a number of experimental results for a nominally two-dimensional separating turbulent boundary layer for an airfoil-type flow in which the flow was accelerated and then decelerated until separation. Upstream of separation single and cross-wire hot-wire anemometer measurements were also presented. In addition to confirming the earlier conclusions of Simpson et al. (1977), these results provided new insights about the separated flow region. From that work, the backflow appears to be supplied by the large eddy structure rather than coming from far downstream. It also was suggested that downstream of fully-developed separation the mean backflow could be divided into three layers: a viscous layer nearest the wall that is dominated by the turbulent flow unsteadiness but with little Reynolds shearing stress effects; a rather uniform mean velocity intermediate layer that seems to act as an overlap region between the viscous wall and outer regions; and the outer backflow region that is really part of the large-scaled outer region. The results presented here support the earlier flow model of Simpson et al. (1980).
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1980
- Accession Number
- ADA095256
Entities
People
- B. G. Shivaprasad
- Klara Shiloh
- R. L. Simpson
Organizations
- Purdue University