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中文核心期刊

出口爆轰的外流场研究

Investigations on external flow field of an exited detonation

  • 摘要: 利用内径为30mm, 长度为1000mm的爆轰管,对脉冲爆轰发动机进行研究. 爆轰管内充满氢气-氧气-氮气预混气,采用底端中心点火. 对半球形高温火团引发的氢气-氧气-氮气爆轰过程和管内、外流场分布进行轴对称数值模拟,考虑了H_2-O_2-N_2的详细化学反应动力学机理,该机理包含了19个基元反应和9种组份. 实验和计算获得的外流场阴影和数值照片,形象地描述了管外流场的变化. 数值计算结果和实验结果基本一致,根据实验和数值计算结果,详细地讨论了悬吊激波产生的动力学机理. 爆轰波溢出爆轰管后,斜压效应和Helmholtz不稳定导致涡环的产生,同时在流场中形成止于涡环的悬吊激波,涡环形状的变化又引起悬吊激波的强度、形状和位置的变化.

     

    Abstract: Pulse Detonation Engine (PDE) tests in the PDE tubeH_2-O_2-N_2 have beenperformed with central ignition in the tube end. The tube has 1000mm longwith the inner diameterof 30mm, filled with the H_2-O_2-N_2 mixture.Moreover, numerical simulationsof pulse detonation process induced by flame in the tube withH_2-O_2-N_2 mixture andthe distribution of the internal and external flow field were performed. Adetailed chemical mechanism of H_2-O_2-N_2 system was investigatedwith 19 element reactions and9 species. The generation and development of the vortex ring and suspendedshock were exhibited with the sequential shadowgraphs of the external flowfield both in test and simulation. The numerical results were in goodagreement with the measured results. The experimental and numerical resultsshow that the vortex ring was induced by baroclinic effect and Helmholtzinstability in the vicinity of the thruster exit after the donation waveexhausted the tube. The intensity, shape and location of the suspended shockvaried when the shape of the vortex ring changed.

     

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