摘要
吸气式激光推进的激光能量沉积过程主要发生在激光支持的爆轰波(LSD波)的形成与演化阶段,分析LSD波的传播规律和影响因素对揭示能量沉积机理起到基础性作用。利用纳秒四分幅高速相机和延长光路的纹影系统,拍摄了不同聚焦角度下CO2激光经透镜聚焦击穿空气流场的纹影照片,结合一维理论公式分析了LSD波速度。结果表明:在本文的实验条件下,吸气式激光推进击穿空气经历了LSD波和激光支持的燃烧波(LSC波)两个阶段,LSD波阶段的持续时间约7.1μs;3种聚焦角度下LSD波速度与理论公式预测的整体趋势比较吻合;聚焦角度越小,LSD波的初始速度越大,聚焦角度θ=4.29°时实验数据达到约14km/s。
Energy deposition in air-breathing laser propulsion usually occurs during the formation and evolution of laser-supported detonation （LSD） wave. Therefore, analyses of propagation laws and influence factors of LSD wave play a fundamental role in disclosing the mechanism of energy deposition. The scblieren photographs of CO2 laser-induced air breakdown at different focusing angles are taken with a nanosecond framing high-speed camera. During the process, an optical lens is used and ray path of the schlieren system is extended. Further, the wave velocity is also analyzed through the one-dimensional theoretical formula. The results indicate that ① under the given experimental conditions, the process of the air breakdown in air-breathing laser propulsion includes two stages： the I.SD wave stage and the laser-supported combustion （LSC） wave stage. The duration of the former stage lasts approximately 7. 1 μs; ② at three different focusing angles, the overall trend of LSD wave velocity obtained in experiment is generally consistent with the estimated one predicted by the theoretical formula. The smaller the focusing angle is, the faster the initial LSD wave velocity is; it reaches about 14 km/s when the angle is 4.29°.
出处
《航空学报》
EI
CAS
CSCD
北大核心
2009年第9期1571-1575,共5页
Acta Aeronautica et Astronautica Sinica
基金
国家"973"基础研究
国家自然科学基金(10672184)
关键词
激光推进
聚焦角度
空气击穿
LSD波
LSC波
纹影系统
laser propulsion
focusing angle
air breakdown
laser-supported detonation wave
laser-supported combustion wave
schlieren systems
