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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2.31m增至12.62m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 5×105Pa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12.62m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568nm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568nm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 the specific density of Al / AP bimodal powder rocket engine, the Al / AP powder rocket engine ignition test was carried out by increasing the characteristic length of the combustion chamber from 2.31m to 12.62m. The ignition delay, combustion time and combustion stability of Al / AP mixture in 1.0132 5 × 105Pa nitrogen atmosphere were studied by spectrometer, CCD camera and CO2 laser igniter. The apparent bulk density of Al particles was measured. Magnesium particles have also been studied as an alternative fuel. The results show that when the characteristic length of the combustion chamber is increased to 12.62m, the maximum combustor pressure oscillation amplitude of ± 2.43% can be obtained. The light intensity of Al / AP mixture containing 1μm aluminum powder was far greater than that of aluminum powder with particle size of 10μm. The photon number of the emission spectrum at 568nm exceeded the detection limit of 65000 by spectrometer. However, the 568nm emission spectra of the 10μm aluminum powder samples were discontinuous and their full-length intensities were below 19 036. The ignition delay time of aluminum powder with particle size of 10μm is 3.65 times of the ignition delay time of aluminum powder with particle size of 1μm, the burning time is 3.03 times, the maximum RAlO is 14.3% less than 1μm aluminum powder and the density is 21.3% Has better combustion performance, but its bulk density is lower. Although the theoretical specific impulse of Mg / AP is 95.6% of Al / AP, its bulk density is 8% higher than that of 1μm aluminum powder and its ignition delay time is 90.3% shorter than that of 10μm aluminum powder. Flame photographs also show that magnesium powder can greatly reduce the deposition of coagulation.