Thrust nozzle design study for a quasi-axisymmetric scramjet-powered vehicle

The design of a nozzle of an unfueled quasi-axisymmetric scramjet model is optimized for minimum drag for a Mach 8 flight condition. The approach to the nozzle design is to develop a simple force-prediction methodology in an optimization study. The study is completed for an unfueled configuration, but the approach could be used for fueled configuration by including appropriate combustion modeling. The effects of the nozzle design on the overall vehicle performance are included. The overall drag of the baseline model for the optimization study was measured in the T4 shock tunnel for Mach numbers ranging from 5.7 to 10.3, confirming the suitability of the force-prediction methodology. The results of the nozzle-optimization study show that performance is limited by the nozzle area ratio that can be incorporated into the vehicle without leading to too large of a base diameter of the vehicle and increasing the external drag of the vehicle. The drag of vehicle designs at different flight Mach numbers is investigated in a parametric study for Mach numbers from 6 to 10. The results confirm that longer nozzles are better at higher Mach numbers.