Turbulent Molecular Processes and Structures in Supersonic Free Shear Layers
Abstract
We used our Ludwieg tube-wind-tunnel to determine Reynolds number and Mach number effects on the dynamics of coherent structures in a supersonic free shear layer. We proposed to implement fluorescence in NO2 as a local point density diagnostic and to develop a capacity of simultaneous three dimensional measurements of velocity and Reynolds number histories in the free shear layer and to determine as well the axial and transverse profiles for such a flow. Using a Mach number 2.5 nozzle, we have confirmed our previously published evidence of Reynolds number sensitivity in supersonic turbulent shocklets in compressible free shear layers. We have determined that shocklet-producing entities are low velocity systems in these flows and have impact on the local scales associated with turbulent effects. We have determined a local evolution of coherence in the Reynolds stress data, using both phase coherence velocimetry and new techniques for direct velocity estimations, between the on-axis and off- axis regions of the free shear layer. We find that classical turbulent effects are in a long-wavelength range while effects accompanying chaos are at short wavelengths, -- with fractal dimensions which suggest that the observed chaotic behavior evolves from instabilities in flow which is topologically two dimensional.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1990
- Accession Number
- ADA236922
Entities
People
- Joseph A. Johnson Iii
Organizations
- City College of New York