塞式喷管底部特性研究

Investigation on Aerospike Nozzle Base Behaviour

基于实验数据和数值模拟结果,研究了外界反压和底部二次流对塞式喷管底部的影响。实验表明,底部压强分布相对较均匀,底部在不同外界反压下具有不同的气动状态。如果主流在底部受压缩,底部有气动开放的趋势;如果主流在底部受膨胀,底部有气动闭合的趋势;如果底部同时存在压缩和膨胀,其状态与受到压缩和膨胀的相对强弱有关。二次流的注入使底部开闭过渡点的压比值升高,底部闭合后的压强值增大,有利于防止底部开闭过渡时推力出现较大幅度降低。二次流流量达到主流的2 0%后,加大底部二次流流量不再影响底部压强,过多地注入反而会降低塞式喷管的总体效率,1 5%～2 0%主流流量的二次流注入是比较好的选择。

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 conparatively 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 dominatinglyexpanded 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 20% base bleed ratio is the optimum value range.