A comparison of the turbulence structure of subsonic and supersonic boundary layers

Abstract

A comparison of the turbulence structure of subsonic and supersonic boundary layers reveals that, despite broad similarities, significant differences exist. The length scales derived from space-time correlations indicate that the spanwise scales are almost identical but that the streamwise scales in the supersonic flow are about half the size of those in subsonic flow. The large-scale structures in the subsonic boundary layer appear to move slightly slower, and lean more toward the wall than those observed in supersonic flows, and their shear stress content is distributed differently among the four quadrants. These observations should have a strong impact on deriving turbulence models for high Reynolds number supersonic flows.

Experimental study of a supersonic turbulent boundary layer using PIV

“…This may explain the relatively large discrepancies between the present Reynolds stress profiles and the other results near the edge of the boundary layer. Nevertheless, the present Reynolds normal stress profile shows a good agreement with the experimental results of Muck et al [23] and Smits et al [12] for 0.4<y/< 0.8, despite a significantly higher Reynolds number Re  in their flows. The LES result displays a relatively lower value than the experimental data for y/  >0.4, which may be due to the low-Reynolds-number effects.…”

“…However, the log-law region extending farther in the wall-normal direction in the present study is probably due to the large velocity gradient in supersonic boundary layers. And the fact that the intermittency profile in a supersonic boundary layer is fuller than the corresponding subsonic profile may be another explanation, according to Smits et al [12].…”

“…Experimental data reported by Smits and Dussauge [10] also confirm that supersonic boundary layers at zero pressure gradient exhibit close similarities with incompressible ones. However, recent experimental work has indicated that the turbulent structures of subsonic and supersonic boundary layers are different in some ways [12]. Therefore, further investigations of the supersonic turbulent boundary layer are necessary.…”

Influence of Surface Roughness on the Second Order Transport of Turbulence in Non-Equilibrium Boundary Layers

“…a contraction of equation (1.1) neglecting the pressure work terms), and has provided the rationale for using incompressible turbulence models for flows up to Mach 5. While scaling for compressibility has been found to correlate the mean velocity with the low-speed database across smooth boundary layers [Van Driest (1951)] more recent experiments suggest that for turbulent quantities the current database is insufficient [Fernholz et al ( 1981), Smits et al (1989), Spina et al (1994), Dussauge et al (1996) and Smits and Dussauge (1996)] even for smooth flat plate boundary layers and that Morkovin's hypothesis may be more restrictive than originally believed.…”

Influence of Surface Roughness and Freestream Turbulence on the Second Order Transport of Turbulence in Non-Equilibrium Boundary Layers

“…Scaling for compressibility has been found to correlate the mean velocity with the low-speed database across smooth boundary layers [Van Driest (1951)]. More recently, detailed compilations and analyses of available high-speed turbulence smooth wall data [Fernholz et al (1981), Smits et al (1989), Spina et al (1994), Dussuage et al (1996) and Smits and Dussuage (1996)] have been performed. In summary, the studies indicated that the database was insufficient to confirm turbulent property scaling and the realm of applicability of Morkovin's hypothesis might be more restrictive than originally believed.…”