Experimental investigation of nonequilibrium and separation scaling in double-wedge and double-cone geometries

Knisely, Andrew M

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https://hdl.handle.net/2142/95291 Copy

Description

Title

Experimental investigation of nonequilibrium and separation scaling in double-wedge and double-cone geometries

Author(s)

Knisely, Andrew M

Issue Date

2016-10-12

Director of Research (if dissertation) or Advisor (if thesis)

Austin, Joanna

Doctoral Committee Chair(s)

Dutton, J. Craig

Committee Member(s)

• Panesi, Marco
• Lee, Tonghun

Department of Study

Aerospace Engineering

Discipline

Aerospace Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Hypersonic
• Compressible Flow
• Double-Wedge
• Double-Cone
• T5 Reflected Shock Tunnel
• Expansion Tube
• Shock Boundary Layer Interactions
• Schlieren
• Heat Flux

Abstract

Experiments were performed in the Hypervelocity Expansion Tube (HET) and the T5 hypervelocity shock tunnel to investigate geometric and gas composition effects on a double-wedge and double-cone geometry. The high-speed flow over the models results in a complex shock boundary-layer interaction which is known to be sensitive to thermal and chemical nonequilibrium. High-speed shadowgraph and surface heat flux measurements are obtained for both geometries. Surface heat flux measurements of the laminar boundary layer for the double-wedge show good agreement between both facilities with proper nondimensionalization. High-speed shadowgraph imaging is used to study the flowfield startup processes. The shock interactions and separation location exhibit no transient processes once the nozzle reservoir reaches a steady stagnation pressure level in T5. Two of the primary shock-shock interaction types are identified for the double-cone. Augmented heat flux is observed for the Edney Type V interactions with the highest peak heating observed with the nitrogen test gas. However, transient heat flux measurements during the nozzle startup indicate that the peak heat flux is not captured by the thermocouples for the air case due to the highly local nature of heating in this shock configuration. The boundary-layer separation scaling based on triple-deck theory for a double-wedge is applied to the double-cone geometry. The pressure correlation for the double-cone is found to be in agreement with historical results. No significant response of the separation length to the gas composition, apart from changes in the freestream condition, are observed for the current experiments. In purely laminar interactions no dependence of the scaled separation on Reynolds number is observed. Reattachment heat flux indicates transitional behavior of the separated boundary layer for the high Reynolds number conditions. A consistent decrease in scaled separation length is found for transitional interactions.

Graduation Semester

2016-12

Type of Resource

text

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http://hdl.handle.net/2142/95291

Copyright and License Information

Copyright 2016 Andrew Marshall Knisely

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