Hypervelocity Carbon Dioxide Flow Simulation

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This paper reports on a series of experiments performed in the superorbital expansion tunnel at the University of Queensland. Carbon dioxide was used as the test gas, and flow velocities up to 13 km/sec were recorded. Static pressure and flat plate heat transfer measurements in the test section indicated that steady test flows of the order to 10 microseconds were obtained. Flow condition was estimated using an equilibrium analysis, accounting for shock reflection from the tertiary diaphragm, and for secondary shock attenuation during its passage through the test gas. The flow properties thus obtained were used to estimate the theoretical flat plate heat transfer using an equilibrium reference enthalpy correlation, and measurements were made on a small flat plate model instrumented with thin film heat transfer gauges. The shape of the profiles against distance was consistent with steady laminar boundary layer flow for the duration of the test time, but the absolute values of measured heat transfer were significantly lower than the correlation’s. The reason for this is not clear at present, but is consistent with the findings of other researchers using carbon dioxide at lower enthalpies. The experiments confirm that conditions suitable for further aerodynamic testing have been created.