Analysis of Windward Side Hypersonic Boundary Layer Transition on Blunted Cones at Angle of Attack
AFRL/RQHF Wright-Patterson Air Force Base United States
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The seven-degree half-angle cone is a canonical geometry for high-speed boundary-layer transition. This paper presents constant N-Factor transition predictions for the Mack 2nd Mode along the windward plane for this geometry at differing angles of attack and differing nose radii in preparation for an upcoming experimental series. The stability analyses are able to capture the experimental trends seen in previous experiments. Computationally derived entropy swallowing lengths are shown to largely match the trends derived analytically in previous studies. These entropy swallowing lengths appear to be applicable as a figure of merit for transition studies, even at angles of attack. Bluntness appears to delay the amplification of Mack 2nd mode instabilities along the attachment line, rather than increasing the critical amplitude leading to transition. As is the case for cones at zero angle of attack, when transition occurs within the swallowing distance along the attachment line, it does not appear to be well-correlated with PSELST N-Factors.
- Fluid Mechanics