Use of shear-stress-sensitive, temperature-insensitive liquid crystals for hypersonic boundary-layer transition detection

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The use of shear-stress-sensitive, temperature-insensitive (SSS/TI) liquid crystals (LCs) has been evaluated as a boundary-layer transition detection technique for hypersonic flows. Experiments were conducted at Mach 8 in the Sandia National Laboratories Hypersonic Wind Tunnel using a flat plate model at near zero-degree angle of attack over the freestream unit Reynolds number range 1.2-5.8x10{sup 6}/ft. Standard 35mm color photography and Super VHS color video were used to record LC color changes due to varying surface shear stress during the transition process for a range of commercial SSS liquid crystals. Visual transition data were compared to an established method using calorimetric ... continued below

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29 p.

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Aeschliman, D.P.; Croll, R.H. & Kuntz, D.W. April 1, 1997.

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This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 42 times . More information about this report can be viewed below.

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  • Sandia National Laboratories
    Publisher Info: Sandia National Labs., Albuquerque, NM (United States)
    Place of Publication: Albuquerque, New Mexico

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Description

The use of shear-stress-sensitive, temperature-insensitive (SSS/TI) liquid crystals (LCs) has been evaluated as a boundary-layer transition detection technique for hypersonic flows. Experiments were conducted at Mach 8 in the Sandia National Laboratories Hypersonic Wind Tunnel using a flat plate model at near zero-degree angle of attack over the freestream unit Reynolds number range 1.2-5.8x10{sup 6}/ft. Standard 35mm color photography and Super VHS color video were used to record LC color changes due to varying surface shear stress during the transition process for a range of commercial SSS liquid crystals. Visual transition data were compared to an established method using calorimetric surface heat-transfer measurements to evaluate the LC technique. It is concluded that the use of SSS/TI LCs can be an inexpensive, safe, and easy to use boundary-layer transition detection method for hypersonic flows. However, a valid interpretation of the visual records requires careful attention to illumination intensity levels and uniformity, lighting and viewing angles, some prior understanding of the general character of the flow, and the selection of the appropriate liquid crystal for the particular flow conditions.

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29 p.

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OSTI as DE97005911

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  • Other Information: PBD: Apr 1997

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  • Other: DE97005911
  • Report No.: SAND--92-2469
  • Grant Number: AC04-94AL85000
  • DOI: 10.2172/469193 | External Link
  • Office of Scientific & Technical Information Report Number: 469193
  • Archival Resource Key: ark:/67531/metadc676889

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Creation Date

  • April 1, 1997

Added to The UNT Digital Library

  • July 25, 2015, 2:21 a.m.

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  • April 14, 2016, 9:09 p.m.

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Aeschliman, D.P.; Croll, R.H. & Kuntz, D.W. Use of shear-stress-sensitive, temperature-insensitive liquid crystals for hypersonic boundary-layer transition detection, report, April 1, 1997; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc676889/: accessed May 27, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.