Proper Orthogonal Decomposition Analysis of Hypersonic Turbulent Boundary Layers Subjected to Streamline Wall Curvature

摘要

The modal structure of a Mach 4.9 turbulent boundary layer subjected to streamline curvature-induced pressure gradients were characterized by proper orthogonal decomposition (POD) analysis. Planar particle image velocimetry (PIV) was used to probe the flow over favorable and adverse pressure gradients. The POD analysis showed that adverse pressure gradient consolidates the energy distribution into fewer modes while favorable pressure gradient promotes increased energy distribution to additional POD modes. Visualization of the first six POD mode contours enabled qualitative comparison between each case. For all but the strong FPG case, the first mode exhibited the anticipated boundary layer wall-normal velocity gradient features. For the strong FPG, the bulk expansion dominated the energy distribution in the first POD mode. This work is ongoing with a new wind tunnel facility under development followed by stereoscopic PIV measurements.