The Stability of Two-Dimensional Wakes and Shear-Layers at High Mach Numbers
Abstract
This study is concerned with the stability properties of laminar free shear-layer flows, and in particular symmetric two-dimensional wakes, for the subsonic through the hypersonic regime. Emphasis is given to the use of proper wake profiles that satisfy the equations of motion at high Reynolds numbers. In particular we study the inviscid stability of a developing two-dimensional wake as it accelerates at the trailing edge of a splitter plate. The non-parallelism of the flow is a leading order effect, and the undisturbed state is solved numerically. The neutral stability characteristics are computed numerically and the hypersonic stability is obtained by increasing the Mach number. It is found that the neutral stability characteristics are altered significantly as the wake develops. Multiple modes (second modes) are found in the near-wake develops mode multiplicity is delayed to higher and higher Mach numbers. At a distance of about one plate length from the trailing edge, there is only one mode in a Mach number range of zero to twenty. The dominant mode emerging at all wake stations and for high enough Mach numbers is the so-called vorticity mode, which is centered around the generalized inflection point layer. The structure of the dominant mode is also obtained analytically for all streamwise wake locations and it is shown how the far-wake limit is approached. Asymptotic results for the hypersonic mixing layer given by a tanh and a Lock distribution are also given. (jhd)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1990
- Accession Number
- ADA227156
Entities
People
- D. T. Papageorgiou