On the Nature of Oblique Instability Waves in Boundary Layer Transition.
Abstract
An experimental study of boundary layer transition is conducted using the active surface heating technique. This technique is extended to provide a means for controllably and repeatedly introducing three dimensional disturbances into a laminar boundary layer. These generated harmonics are not sufficient to explain the transition from small linear oscillations to the large amplitude, broad band, three dimensional oscillations characteristic of a fully turbulent boundary layer. The effect of three dimensionality on boundary layer transition is then investigated through an analytical and experimental study of single oblique instability waves. Through a series of experiments, it is shown that certain conditions exist for which oblique waves are observed to be more unstable than any two dimensional wave. It is shown that oblique waves exhibit a non stationary period doubling behavior that is not seen in two-dimensional disturbances. A vortex pairing mechanism is proposed to explain the behavior, and is shown to occur in a manner consistent with the Biot-Savart law for the induced velocity field.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 23, 1986
- Accession Number
- ADA188812
Entities
People
- Harry F. Robey Iii
Organizations
- California Institute of Technology