Determination of Shock Tube Boundary Layer Parameter Utilizing Flow Marking,
HANOVER UNIV (GERMANY F R) INST FUER PLASMAPHYSIK
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In shock tube flow a fluid particle is marked by laser-induced breakdown. The marking is detected about 15 cm downstream by a schlieren arrangement. The error in distance and time is less than 2 percent. The particle paths are influenced by both wall boundary layers and attenuation, the latter being known from a shock path measurement with high accuracy. Thus flow marking provides a method to check the shock tube boundary layer models and to determine the value of a parameter characterizing the mass loss term of the free stream. The marking measurements are compared with numerical computations of the nonequilibrium flow starting from the actual shock path. If the flow is marked in the initial zone where the influence of chemical reactions on the flow velocity is negligible simple analytic formulae can be used instead.