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测量了使用含铝推进剂的小型二维火箭发动机中燃烧室、尾喷管和排气羽烟中粒子的粒径分布。采用了不同的喷管形状和高达4.36MPa的压强。压强低于约2.4MPa时,进入喷管的粒子多峰尺寸分布的D_(32)随压强的增大而减小。大于2.4MPa时,更高的推进剂燃速显著降低了微粒团聚作用,并提高了特征排气速度。在更高的压强下,进入喷管的粒子的D_(32)非常小(2～16μm)并且是单峰的,随压强没有明显的改变。在发动机关闭过程中,D_(32)明显比稳定燃烧过程中的大,揭示了羽烟特征改变的又一可能原因。排出微粒的D_(32)为1.2～1.6μm(伴随着2μm以下,8μm,28μm三峰分布),这与压强、喷管入口形状、出口马赫数、不完全膨胀程度或出口平面的后部配置无关。少量较大颗粒的存在表明,或者是在喷管接合部发生了微粒碰撞和/或表面影响,或者是在喷管进口处较大微粒集中在壁面附近。
The particle size distribution of the particles in the combustion chamber, tail pipe and exhaust plumes was measured in a small two-dimensional rocket motor using aluminum-containing propellants. Different nozzle shapes and pressures up to 4.36 MPa are used. When the pressure is lower than about 2.4MPa, the D_ (32) of the multimodal particle size distribution of the nozzle decreases with the increase of pressure. Above 2.4 MPa, a higher propellant burn rate significantly reduces particle agglomeration and increases the characteristic exhaust velocity. At higher pressures, the D_ (32) of the particles entering the nozzle is very small (2 to 16 μm) and unimodal with no significant change in pressure. During engine shutdown, D 32 was significantly larger than during steady combustion, revealing yet another possible cause of plume smoke characteristics changes. The D_ (32) of the discharged particles is 1.2 to 1.6 μm (accompanied by a three-peak distribution of 2 μm or less, 8 μm or 28 μm) irrespectively of the pressure, the nozzle inlet shape, the outlet Mach number, the degree of incomplete expansion, or the rear configuration of the exit plane . The presence of a small amount of larger particles indicates either that particle collisions and / or surface effects occur at the nozzle juncture or that larger particles are concentrated near the wall at the nozzle inlet.