Dense gas boundary layer experiments: Visualization, pressure measurements, concentration evaluation
- Ernst-Mach-Institut, Freiburg (DE)
- R and D Associates, Los Angeles, CA (United States)
This technical report describes methods that were applied to investigate turbulent boundary layers generated by inviscid, baroclinic effects. The Cranz-Schardin 24-sparks camera was used to visualize the interactions of a planar shock wave with a Freon R12-layer. The shock propagates more slowly in the Freon layer than in air because of its smaller sound speed. This causes the shock front to be curved and to be reflected between the wall and the layer interface. As a consequence of the reflection process, a series of compression and expansion waves radiate from the layer. Large fluctuations in the streamwise velocity and in pressure develop for about 1 ms. These waves strongly perturb the interface shear layer, which rapidly transitions to a turbulent boundary flow. Pressure measurements showed that the fluctuations in the Freon layer reach a peak pressure 4 times higher than in the turbulent boundary flow. To characterize the preshock Freon boundary layer, concentration measurements were performed with a differential interferometry technique. The refraction index of Freon R12 is so high that Mach-Zehnder interferometry was not successful in these experiments. The evaluation of the concentration profile is described here in detail. Method and results of corresponding LDV measurements under the same conditions are presented in a different report, EMI Report T 9/92. The authors plan to continue the dense gas layer investigations with the gas combination helium/Freon.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ernst Mach Inst., Freiburg (Germany); R and D Associates, Los Angeles, CA (United States)
- Sponsoring Organization:
- Department of Defense, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10181194
- Report Number(s):
- UCRL-CR-113693; ON: DE93019608; CNN: Contract DNA 001-91-C-0039; TRN: 93:003204
- Resource Relation:
- Other Information: PBD: Nov 1992
- Country of Publication:
- United States
- Language:
- English
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