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Experimental study of second-mode instability growth and breakdown in a hypersonic boundary layer using high-speed schlieren visualization

Laurence, Stuart and Wagner, Alexander and Hannemann, Klaus (2016) Experimental study of second-mode instability growth and breakdown in a hypersonic boundary layer using high-speed schlieren visualization. Journal of Fluid Mechanics, 797, pp. 471-503. Cambridge University Press. doi: 10.1017/jfm.2016.280. ISSN 0022-1120.

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Official URL: https://doi.org/10.1017/jfm.2016.280


Visualization experiments are performed to investigate the development of instability waves within the boundary layer on a slender cone under high Mach number conditions. The experimental facility is a reflected-shock wind tunnel, allowing both low (Mach-8 flight equivalent) and high-enthalpy conditions to be simulated. Second-mode instability waves are visualized using a high-speed schlieren set-up, with pulse bursting of the light source allowing the propagation speed of the wavepackets to be unambiguously resolved. This, in combination with wavelength information derived from the images, enables the calculation of the disturbance frequencies. At the lower-enthalpy conditions, we concentrate on the late laminar and transitional regions of the flow. General characteristics are revealed through time-resolved and ensemble-averaged spectra on both smooth and porous ceramic surfaces of the cone. Analysis of the development of individual wavepackets is then performed. It is found that the wavepacket structures evolve from a ‘rope-like’ appearance to become more interwoven as the disturbance nears breakdown. The wall-normal disturbance distributions of both the fundamental and first harmonic, which initially have local maxima at the wall and near y=_ D 0:7–0.75, exhibit an increase in signal energy close to the boundary-layer edge during this evolution. The structure angle of the disturbances also undergoes subtle changes as the wavepacket develops prior to breakdown. Experiments are also performed at high-enthalpy (h0 _ 12 MJ kg

Item URL in elib:https://elib.dlr.de/105858/
Document Type:Article
Additional Information:J. Fluid Mech. (2016), vol. 797, pp. 471-503.; Cambridge University Press 2016 first published online 23 May 2016
Title:Experimental study of second-mode instability growth and breakdown in a hypersonic boundary layer using high-speed schlieren visualization
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Date:23 May 2016
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 471-503
EditorsEmailEditor's ORCID iDORCID Put Code
Publisher:Cambridge University Press
Keywords:compressible boundary layers, high-speed flow, transition to turbulence
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transportation
DLR - Research area:Raumfahrt
DLR - Program:R RP - Space Transportation
DLR - Research theme (Project):R - Raumfahrzeugsysteme - Anlagen u. Messtechnik (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Spacecraft
Deposited By: Bachmann, Barbara
Deposited On:17 Jan 2017 11:34
Last Modified:21 Sep 2023 12:45

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