为了使Al/AP双组元粉末火箭发动机密度比冲最大化,将燃烧室特征长度由2.31 m增至 12.62 m进行了Al/AP粉末火箭发动机点火测试.采用光谱仪、CCD 相机、CO2 激光点火器等对 Al/AP 混合物在 1.0132 5 × 105 Pa的氮气环境中的点火延迟、燃烧时间、燃烧平稳性等燃烧性能进行了研究.测量了Al颗粒的表观堆积密度.作为一种替代燃料,对镁颗粒也进行了研究.结果表明,增加燃烧室特征长度至 12.62 m 时,可以得到最大燃烧室压强振荡幅度±2 .43%的平稳燃烧性能.含粒径 1μm 铝粉的 Al/AP 混合物其燃烧过程的光强远大于含粒径10μm铝粉的样品,并且其在波长 568 nm 发射光谱的光子数强度超过了光谱仪检测上限(65 000 数).而含粒径10μm铝粉样品燃烧过程的568 nm发射光谱信号出现间断且其全程强度低于 19 036 数.粒径 10μm 铝粉点火延迟时间为粒径1μm铝粉点火延迟时间的3.65 倍,燃烧时间为3.03 倍以上,最大RAlO却比 1μm铝粉少 14.3%,密度低21 .3%,说明粒度小的铝粉具有更好的燃烧性能,但是其堆积密度也更低.虽然Mg/AP的理论比冲为Al/AP的95.6%,但是其堆积密度比粒径1μm铝粉高8%,其点火延迟时间比粒径10μm铝粉短 90.3%.火焰照片也表明镁粉可在很大程度上减少凝相沉积.%In order to maximize density specific impulse of the Al/AP bipropellant powder rocket engine,the fire tests on Al/AP powder rocket engine were carried out with increasing the characteristic length of combustion chamber from 2.31 m to 12.62 m. Combustion performances of Al/AP mixtures such as ignition delay,burn time,combustion smoothness and intensity of vapor phase reaction in nitrogen under atmospheric pressure were studied by using spectrometer,CCD camera and CO2 laser igniter.Ap-parent packing densities of samples were measured.As an alternative fuel,the magnesium particles were also studied.The results show that,increasing chamber characteristic length from 2.31 m to 12.62 m produces smoother combustion with ±2.43% maxi-mum amplitude of chamber pressure oscillation.Flame of Al/AP mixture with 1μm Al particles is much more luminous than that with 10μm Al particles.And the continuous emission signal intensity of Al/AP mixture with 1μm Al particles at 568 nm exceeds the upper limit (65 000 counts)of the spectrometer,rather than Al/AP mixture with 10μm Al particles with continuous intervals among combustion process and lower emission signal intensity at 568nm of below 19 036 counts.Ignition delay and burn time of 10μm Al particles are 3.65 times and 3.03 times as 1μm Al particles,respectively.But the maximumRAlO and packing density are 14.3% and 21.3% less than 1μm Al powder,showing that smaller Al particles have better combustion performance but lower packing density.Although the theoretical specific impulse of the Mg/AP propellant is 95.6%of the Al/AP,its bulk density is 8%higher than 1μm Al powder,and the ignition delay is 90.3%shorter than 10μm particles.Flame images also show that magnesium can largely reduce the condensed phase deposition.
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