Effects of Impurities on Shock Wave Stability and Structure in Ionizing Monatomic Gases.
TORONTO UNIV (ONTARIO) INST FOR AEROSPACE STUDIES
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The effects of impurities - hydrogen, water vapour and sodium chloride - on shock wave stability and structure in ionizing-argon and krypton flows were investigated by using a dual-wavelength Mach-Zehnder interferometer in conjunction with the UTIAS 10cm x 18cm 4in x 7in Hypervelocity Shock Tube. At shock Mach number of about 15, when pure argon or krypton is used as a test gas, the resulting translational shock front develops sinusoidal oscillations. The subsequent ionization relaxation region, the electron-cascade front and the quasi-equilibrium state also exhibit unstable characteristics. The addition of small amounts of hydrogen or 0.5 by pressure to the test gas stabilizes the entire flow and at the same time drastically shortens the relaxation length to about 13 of the original value in argon and 23 in krypton. The addition of about 1 of water vapour by pressure to the argon test gas also stabilizes the flow and shortens the relaxation region. A thin coating of dissolved sodium chloride in water on the shock tube wall, which on evacuation leaves a rough surface of crystals, however, does not seem to have any effect on the flow.
- Fluid Mechanics