Three-Dimensional Interactions and Vortical Flows with Emphasis on High Speeds
Abstract
This report discusses diverse kinds of three-dimensional regions of separation in laminar and turbulent boundary layers that exist on lifting aerodynamic configurations immersed in flows from subsonic to hypersonic speeds. One of the common ingredients is that a 3-D boundary layer will detach from a surface along a swept separation line (adjacent to which the skin-friction lines converge rapidly) and will usually form a well organized coiled motion in all speed regimes. The scale of the vortical flow relative to the undisturbed boundary-layer thickness delta sub 0 changes, depending on the configuration and its attitude to the free stream. In axial corner and bluff protuberance flows, the coiled shear layer is immersed within delta sub 0. About slender bodies or sharp swept-back wings at angle of attack, the vortical flow is many times larger than delta sub 0, compressibility generally suppressing the scale. In hypersonic flow, high rates of heat transfer are encountered along lines of reattachment (adjacent to which the skin-friction lines diverge rapidly) that are associated with 3-D separation zones. The maximum rates of heat transfer -- rates that may exceed the local stagnation point heating by factors of 10 or more -- result from shock-on-shock interactions situated, not on the surface, but in the flow field in proximity to forward-facing parts of the airframe. In all cases of 3-D flow separation, the assumption of continuous vector fields of skin-friction lines and external-flow streamlines, coupled with simple topology laws, provides a flow grammar whose elemental constituents are the singular points: nodes, foci, and saddles.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1980
- Accession Number
- ADA089865
Entities
People
- David J. Peake
- Murray Tobak
Organizations
- AGARD