Nosetip roughness and spectral analysis of hypersonic boundary layer transition reversal

Conference item

Boundary layer transition on a 7-degree half-angle cone at zero angle of attack with varying bluntness is experimentally investigated in cold Mach 6 flow produced by the High Density Tunnel (HDT) at the University of Oxford. The bluntness Reynolds number, ReRN , defined using freestream conditions and the nose radius, is varied over the range 3 × 104 to 1.5 × 106 . The transition Reynolds number, ReXST , increases with ReRN up to approximately ReRN = 8 × 105 . Beyond this value, ReXST exhibits greater variance and a reversal trend with increasing bluntness, consistent with earlier findings by Stetson [1] and Marineau [2]. The boundary and entropy layers are studied simultaneously using high-speed schlieren imaging at 500 kHz. Schlieren images are analysed using a range of spectral techniques, including spectral proper orthogonal decomposition (SPOD) and continuous wavelet transforms (CWT). Coherent waves in the boundary and entropy layers are identified, with dominant frequency peaks ranging from 20 kHz to above 160 kHz. This analysis provides further data on the instabilities and flow structures that may constitute the mechanisms and pathways leading to boundary transition reversal under these conditions.

Authors: Ceruzzi, A; Le Page, L; McQuellin, L; McGilvray, M

• Publication status: Accepted
• Peer review status: Peer reviewed
• Publisher: European Space Agency
• Publication date: 2025-05-18
• Acceptance date: 2025-05-18
• Event title: 3rd International Conference on Flight vehicles, Aerothermodynamics and Re-entry (FAR 2025)
• Event location: Arcachon, France
• Event website: https://atpi.eventsair.com/far2025/
• Event start date: 2025-05-18
• Event end date: 2025-05-22
• Language: English
• Keywords: boundary layer transition; spectral analysis; hypersonic flow