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Boundary-Layer Transition on a Slender Cone in Hypervelocity Flow with Real Gas Effects


Jewell, Joseph Stephen (2014) Boundary-Layer Transition on a Slender Cone in Hypervelocity Flow with Real Gas Effects. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9H9935V.


The laminar to turbulent transition process in boundary layer flows in thermochemical nonequilibrium at high enthalpy is measured and characterized. Experiments are performed in the T5 Hypervelocity Reflected Shock Tunnel at Caltech, using a 1 m length 5-degree half angle axisymmetric cone instrumented with 80 fast-response annular thermocouples, complemented by boundary layer stability computations using the STABL software suite. A new mixing tank is added to the shock tube fill apparatus for premixed freestream gas experiments, and a new cleaning procedure results in more consistent transition measurements. Transition location is nondimensionalized using a scaling with the boundary layer thickness, which is correlated with the acoustic properties of the boundary layer, and compared with parabolized stability equation (PSE) analysis. In these nondimensionalized terms, transition delay with increasing CO2 concentration is observed: tests in 100% and 50% CO2, by mass, transition up to 25% and 15% later, respectively, than air experiments. These results are consistent with previous work indicating that CO2 molecules at elevated temperatures absorb acoustic instabilities in the MHz range, which is the expected frequency of the Mack second-mode instability at these conditions, and also consistent with predictions from PSE analysis. A strong unit Reynolds number effect is observed, which is believed to arise from tunnel noise. NTr for air from 5.4 to 13.2 is computed, substantially higher than previously reported for noisy facilities. Time- and spatially-resolved heat transfer traces are used to track the propagation of turbulent spots, and convection rates at 90%, 76%, and 63% of the boundary layer edge velocity, respectively, are observed for the leading edge, centroid, and trailing edge of the spots. A model constructed with these spot propagation parameters is used to infer spot generation rates from measured transition onset to completion distance. Finally, a novel method to control transition location with boundary layer gas injection is investigated. An appropriate porous-metal injector section for the cone is designed and fabricated, and the efficacy of injected CO2 for delaying transition is gauged at various mass flow rates, and compared with both no injection and chemically inert argon injection cases. While CO2 injection seems to delay transition, and argon injection seems to promote it, the experimental results are inconclusive and matching computations do not predict a reduction in N factor from any CO2 injection condition computed.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:hypersonic; hypervelocity; transition; turbulence; turbulent spot; second mode; boundary layer; boundary layer mass injection; transition onset; transition completion; reflected shock tunnel; compressible flow; nonequilibrium flow; nonequilibrium gas dynamics; real gas effects; carbon dioxide; vibrational mode; translational mode
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Minor Option:History
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Shepherd, Joseph E.
Group:Graduate Aeronautical Laboratories (Fluid Mechanics), GALCIT, Explosion Dynamics Laboratory
Thesis Committee:
  • Blanquart, Guillaume (chair)
  • Shepherd, Joseph E.
  • Leyva, Ivett A.
  • Hornung, Hans G.
  • Leonard, Anthony
Defense Date:15 May 2014
Other Numbering System:
Other Numbering System NameOther Numbering System ID
GALCIT ReportFM2014-002
Additional Information:Many individuals contributed substantially to running T5 during the time period covered by this report, in addition to the authors. In roughly chronological order they are: Hans Hornung, Bahram Valiferdowsi, Ivett Leyva, Eric Marineau, Stuart Laurence, and Nick Parziale. Ross Wagnild’s support of the authors’ use of Graham Candler and Heath Johnson’s STABL software suite and the UMNAEM axisymmetric nozzle code made possible many of the computational results presented here. This project was sponsored by the Air Force Office of Scientific Research under award number FA9550-10-1-0491 and the NASA/AFOSR National Center for Hypersonic Research. J. S. Jewell was supported by the National Defense Science and Engineering Graduate Fellowship, the Jack Kent Cooke Foundation Graduate Scholarship, and the Boeing Fellowship. The views expressed herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the sponsors, Caltech, AFOSR, or the U.S. Government.
Funding AgencyGrant Number
Air Force Office of Scientific ResearchFA9550-10-1-0491
National Defense Science and Engineering Graduate FellowshipUNSPECIFIED
Jack Kent Cooke Foundation Graduate ScholarshipUNSPECIFIED
Boeing FellowshipUNSPECIFIED
Record Number:CaltechTHESIS:05292014-220110640
Persistent URL:
Related URLs:
URLURL TypeDescription
http://www.joejewell.comAuthorAuthor's webpage
Jewell, Joseph Stephen0000-0002-4047-9998
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8433
Deposited By: Joseph Jewell
Deposited On:18 Jun 2014 16:41
Last Modified:16 Jan 2021 00:32

Thesis Files

PDF (Single-side printing) - Final Version
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PDF (Double-side printing) - Final Version
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PDF (T5 Conditions Report: Shots 2526-2823. GALCIT Report FM2014.002) - Supplemental Material
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[img] Video (AVI) (Heatflux Movie - T5 Shot 2651 - Spot) - Supplemental Material
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[img] Video (AVI) (Heatflux Movie - T5 Shot 2740) - Supplemental Material
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[img] Video (AVI) (Spot Propagation Simulation - T5 Shot 2740) - Supplemental Material
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