| Popis: |
Expansion tubes are the only type of ground test facility currently able to simulate high Mach number scramjet test flows. These access-to-space flow conditions are characterised by total pressures of the order of gigapascals. The University of Queensland's X2 expansion tube facility has recently been used to generate scramjet flow conditions between Mach 10-14, with total pressures up to 10 GPa. Flow conditions were relevant to a 96 kPa dynamic pressure ascent trajectory. For ground testing of sub-scale scramjet-powered vehicles, pressure-length (p-L) scaling is used in order to maintain similarity for various flight parameters, such as Reynolds number, total enthalpy, and binary reaction rates. X2 was configured to achieve test flow static pressures considerably higher than the true flight values, while maintaining true flight velocities and temperatures, thereby demonstrating significant potential for p-L scaling, which is typically necessary since most model scramjet engines need to be tested at sub-scale. This paper details the combined analytical and numerical process used to develop new flow conditions in X2. Experimental results are presented for four new flow conditions, and axisymmetric CFD analysis is used to fully characterise test flow properties. © 2012 by David E. Gildfind. |
