复合推进剂中铝燃烧实验研究

An Experimental Investigation of Aluminum

关键词:  复合推进剂  铝颗粒  燃烧  高速摄像  团聚

Key words:  Composite propellant  Aluminum particle  Combustion  High-speed photography  Agglomerate

摘要:

采用长焦显微镜头和高速相机组合的光学拍摄方法，研究了不同压强下含铝复合推进剂中铝粒子在推进剂燃烧表面处和脱离燃面后的动态燃烧过程。分别在1MPa，3MPa和5MPa充满氮气的燃烧实验器中进行了实验。在3MPa和5MPa实验中，通过在镜头前增加不同透射率的中性密度滤波片解决了因铝滴燃烧发光过强导致相机成像过度曝光的问题。通过测定拍摄过程中相邻两张图片中同一粒径铝滴在不同位置，计算了不同粒径铝滴的随流运动速率。小粒径随流运动速率快，大粒径随流运动速率慢。实验中还得到了不同粒径铝滴在推进剂燃烧表面的团聚形成时间。1MPa实验下，200μm和150μm粒子的团聚时间分别约为8ms和6ms；3MPa下，300μm和200μm粒子的团聚时间分别约为5ms和3ms；5MPa下，300μm和150μm粒子的团聚时间分别约小于3ms和1ms。随着压强的增大，同一粒径团聚物的团聚时间缩短。在同一压强条件下，粒径越小的铝团聚物其所需团聚时间越短。

Abstract:

For the research of the dynamic combustion process at the surface and out of the burning surface of aluminum in the AP/HTPB propellant，the optical imaging method with the long distance microscope and high-speed camera were used. Experiments were carried out under 1MPa，3MPa and 5MPa filled with nitrogen. Under 3MPa and 5MPa，through the adoption of the neutral density filter (NDFI) with different transmissions in front of the camera，the problem that the overexposure of camera imaging due to the strong light of aluminum droplet combustion was solved，and there was no this problem in 1MPa. Then the flow velocity with the combustion gas was calculated by measuring the various location of the same diameter aluminum drops in the adjacent two images. The flow velocity of small size drops is fast，and the flow velocity of large size drops is slow. The agglomeration time of the aluminum drops in the propellant burning surface was also obtained. In the 1MPa experiment，the agglomeration time of the 200μm and 150μm drops are about 8ms and 6ms. Under 3MPa，the agglomeration time of the 300μm and 200μm drops are about 5ms and 3ms. Under 5MPa，the agglomeration time of the 300μm and 150μm drops are less than 3ms and 1ms. When the pressure increases，the agglomeration time of the same diameter agglomerates becomes shorter. Under the same pressure，the time of the agglomeration with the smaller aluminum agglomerates is shorter.