Influence of Streamline Adverse Pressure Gradients on the Structure of a Mach 5 Turbulent Boundary Layer
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2017 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. The effects of a streamline curvature-induced adverse pressure gradient on the structure of a Mach 4.9 turbulent boundary layer were investigated using particle image velocimetry. The current geometry has impulse parameters of Ip = 0.47 and I = 0.13. Several recent PIV studies have examined the effect of favorable pressure gradients on a fully developed Mach 4.9 turbulent boundary and the present work extends the body of knowledge to the APG case. Mean flow results show the anticipated boundary layer profiles. Detailed analysis of the boundary layer turbulence structure as it navigates the curvature-driven APG was performed. Investigation of the instantaneous shear stress events through probability density function analysis show strengthened turbulence due to the APG. Additionally, two-point spatial correlations show that the outer organizational structure of the turbulence increases as the APG strengthens while near-wall analysis shows that spatial correlations also increase with APG magnitude. Finally, vortex structure analysis provides insight into the connection between the global Reynolds stress values and the behavior of the outer turbulent structures as they negotiate the curvature, leading to the breakup and size reduction of the hairpin vortex packets in the outer region of the boundary layer. Near the wall, the large-scale streamwise turbulent structures are strengthened due to the APG.
