Base Flow Predictions for a Lightsat Launcher at Supersonic Speeds

A numerical investigation of the base flowfield past a lightsat launcher under development in Italy is presented. The analysis regards different points along the flight path in the supersonic regime under axisymmetric conditions and has been focused on the base region of the missile with the aim to investigate the influence of different motor nozzle exit conditions (motor-on and motor-off) and different motor fluid properties (air/combustion products) on the base drag. This activity has been performed using both a Centro Italiano Ricerche Aerospaziali code and the RAMPANT commercial code. A general satisfactory agreement between the two codes is observed in the global aerodynamic coefficients; however, predicted local base pressures show some differences, probably due to the different turbulence models and different numerical methods employed. The numerical results indicate that, in the supersonic flight regime, the base region is only slightly affected by different fluids and motor conditions at the nozzle exit.