Abstract: Based on experimental data and numerical simulation results, effects of ambient pressure and base bleed on aerospike nozzle base behaviour are investigated. It is shown that base pressure distribution is comparatively uniform and base has different aerodynamic behaviours under different ambient pressures. Base has open trend when exhaust flow is dominatingly compressed at base region and closed trend when exhaust flow is dominatingly expanded at base region. Not only the base transition nozzle pressure ratio and base pressure under closed base status are raised, but also base thrust degradation at base open-to-close transition is avoided when some base bleed is employed. Base pressure level is not raised any more when more than 2% base bleed ratio is carried out, as a result the overall efficiency of aerospike nozzle is reduced. It is found that 1.5% to 2% base bleed ratio is the optimum value range.

Key words: rocket engine, propulsion system, experiment, aerospike nozzle, base, performance