Effects of Controlled Three-Dimensional Perturbations on Boundary Layer Transition
Abstract
The laminar-turbulent transition in a flat plate boundary layer was studied experimentally using a spanwise array of computer-controlled surface heating elements to introduce disturbances at a point just downstream of the critical Reynolds number. Measurements were made using flush-mounted hot-film wall shear sensors, and the later stages of transition were visualized using dye injection. Measurements of oblique waves in the linear region yielded phase speeds and wave angles that were consistent with the linear theory. In the nonlinear region, the amplitude of subharmonic waves decreased abruptly with increasing oblique-wave angle, so that an oblique wave of about 10 degrees had a subharmonic amplitude which was an order of magnitude below that for a 2D wave. A simple explanation of this behavior is given, in terms of the wave-interaction theory. The intermittency, was measured to determine the relative location of transition. The introduction of a 2D wave is most effective in moving the transition point upstream for a given power input. (JHD)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 10, 1989
- Accession Number
- ADA215080
Entities
People
- Steven P. Schneider
Organizations
- California Institute of Technology