底部二次流对塞式喷管影响的实验研究

基于单元塞式喷管的实验数据,研究了底部二次流对塞式喷管性能和底部特性的影响,测得了不同环境反压下塞锥表面的压强分布.实验表明,底部在不同压比下具有不同的气动状态.二次流的注入使底部开闭过渡点的压比值升高,底部开始提供推力的压比值下降,有利于避免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,再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.在低压比范围,塞锥表面有压强峰出现,随着高度的增加,压强峰后移并强度减弱.

Experimental studies on the effect of base bleed on aerospike nozzle

Based on experimental data of 1-cell aerospike nozzle, the effect of base bleed on aerospike nozzle performance and base behaviour was presented. Pressure distribution along plug surface under different ambient pressure was obtained. It was shown that base has different aerodynamic behaviour at different ambient pressure. The nozzle pressure ratio at base transition increased and the nozzle pressure ratio at which base thrust starts to be positive decreased when some base bleed was injected. A sudden thrust reduction at base transition was also avoided with base bleed injection. Base pressure level was not increased any more when more than 2.0 % base bleed ratio was carried out ; as a result the overall efficiency of the aerospike nozzle was reduced. It was found that 1.5% to 2.0% base bleed ratio seems to be the optimum value. At low altitude, pressure was raised along the rear part of the plug. With the ambient pressure decreasing, the pressure amplitude became smaller and the pressure rising position moved rearward until out of the plug surface eventually.