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On the Stability of Supersonic Boundary Layers with Injection


Schmidt, Bryan Eric (2016) On the Stability of Supersonic Boundary Layers with Injection. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z93X84M6.


The problem of supersonic flow over a 5 degree half-angle cone with injection of gas through a porous section on the body into the boundary layer is studied experimentally. Three injected gases are used: helium, nitrogen, and RC318 (octafluorocyclobutane). Experiments are performed in a Mach 4 Ludwieg tube with nitrogen as the free stream gas. Shaping of the injector section relative to the rest of the body is found to admit a "tuned" injection rate which minimizes the strength of shock waves formed by injection. A high-speed schlieren imaging system with a framing rate of 290 kHz is used to study the instability in the region of flow downstream of injection, referred to as the injection layer. This work provides the first experimental data on the wavelength, convective speed, and frequency of the instability in such a flow. The stability characteristics of the injection layer are found to be very similar to those of a free shear layer. The findings of this work present a new paradigm for future stability analyses of supersonic flow with injection.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Hypersonics, fluid mechanics, flow stability, compressible flow
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Shepherd, Joseph E.
Group:GALCIT, Explosion Dynamics Laboratory
Thesis Committee:
  • Austin, Joanna M. (chair)
  • Shepherd, Joseph E.
  • Hornung, Hans G.
  • Colonius, Tim
Defense Date:12 May 2016
Record Number:CaltechTHESIS:05252016-141702166
Persistent URL:
Related URLs:
URLURL TypeDescription DocumentAppendix C of the thesis
Schmidt, Bryan Eric0000-0001-9193-7760
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9755
Deposited By: Bryan Schmidt
Deposited On:26 May 2016 19:17
Last Modified:25 Oct 2023 21:09

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