An Investigation of the Inviscid Spatial Instability of Compressible Mixing Layers
Abstract
This dissertation investigates the behavior of both unbounded and bounded compressible plane mixing layers with respect to two- and three- dimensional, spatially growing wave disturbances using linear stability analysis. The mixing layer is formed by two parallel streams with different gases and the flow is assumed to be inviscid and non-reacting. For unbounded mixing layers, the effects of the free-stream Mach number, velocity ratio, temperature ratio, gas constant (molecular weight) ratio and the ratios of specific heats on the linear spatial instability characteristics of a mixing layer are determined. A nearly universal dependence of the normalized maximum amplification rate on the convective Mach number is found for two-dimensional spatially growing disturbances. The effects of the mean flow profiles on the instability behavior of the mixing layers are also studied. It is shown that decreasing the thickness of the total temperature profile relative to the mean velocity profile, or adding a wake component in the mean velocity profile can make the normalized amplification rate decrease slower as the convective Mach number increases for both subsonic and supersonic convective Mach numbers. For an unbounded mixing layer with subsonic convective Mach numbers, there is only one unstable mode propagating with a phase velocity C* sub pm approx. = to the isentropically estimated convective velocity of the large scale structures u* sub c. As the convective Mach number approaches or exceeds unity, there are always two unstable spatial modes.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 18, 1990
- Accession Number
- ADA223776
Entities
People
- Mei Zhuang
Organizations
- California Institute of Technology