Naaseri, M. | Engineering Papers

NASA NTRS1989

Interaction between strong longitudinal vortices and turbulent boundary layers

The latest stages of work on the interaction between longitudinal vortices and turbulent boundary layers show that very large changes in turbulence structure occur when the vortices are strong (crossflow angles of order 20 deg). The changes are poorly correlated by current turbulence models and go well beyond the rotation of the stress tensor in the vortex region that is explicitly represented by the exact 'generation' (exchange) terms in the Reynolds-stress transport equations. Measurements in the interaction between a burst vortex and a boundary layer show qualitatively similar results to the unburst case, but shed useful light on the bursting process itself.

Cutler, A. D.↗

NASA NTRS1988

Burst vortex/boundary layer interaction

Several configurations of delta wing vortex generator and boundary layer test plate were tested, and two final ones selected. Sample measurements and flow visualizations in the candidate configurations, together with more detailed measurements in one of the two final arrangements, which were selected so that a pure vortex bursts repeatably and then interacts, in as simple fashion as possible, with a simple turbulent boundary layer, are included. It is concluded that different intensities of bursting or breakdown, like different strengths of shock wave or hydraulic jump, can be produced by minor changes of configuration. The weaker breakdowns do not produce flow reversal. The initial measurements were done with a fairly weak, but repeatable, breakdown. Basic measurements on the second final arrangement, with a stronger breakdown, are in progress.

Bradshaw, P.↗