物理学报2016，Vol.65Issue(10)：208-215,8.DOI:10.7498/aps.65.104702
一种新的光子多普勒速度频谱分析方法∗
A new metho d to analyze the velo city sp ectrograms of photonic Doppler velo cimetry
摘要
Abstract
Ejecta mixing takes place at the interface between metal and gas under shock loading, i.e., the transport process of ejecta from metal surface happens in gas. Ejecta production and transport processes in gas are the focuses and key problems of shock wave physics at present. So far, extensive investigations have been devoted mainly to the ejecta formation from metal surface under shock-loaded conditions, and many experimental measurement techniques have been developed, such as the Asay foil, high-speed camera and holography technique. As a newly developed instrument, photon Doppler velocitymetry (PDV) which allows the simultaneous detection of velocities of multiple particles has been widely used in the dynamic impact areas, especially in micro-jetting and ejecta mixing experiments. Although PDV spectrogram includes abundant information about ejecta particles, it seems to be too hard to obtain the particle velocity history, which embarrasses the analysis and application of PDV spectrogram. In this paper, the equation of particle motion including the effects of aerodynamic damping force, pressure gradient force, and additional mass force is established, and the analytical solutions of the particle position and velocity are derived in the conditions of planar constant flow, constant flow, and constant acceleration flow. According to the analytical solutions, the characteristics of particle movement are analyzed. A simplified formulation of the relaxation time of the particle velocity, which reflects the particle decelerated speed, is given. And it is found that the relaxation time is proportional to the four-thirds power of particle diameter. Based on the characteristics of particle motion in the planar constant flow, a new method is proposed to analyze the spectrogram of PDV. The fastest velocity of particle in the mixing zone is obtained by extracting the upper part of PDV spectrogram. By integrating the fastest velocity, the time evolution of the head of mixing zone is deduced approximately. The thickness of the mixing zone can be obtained by subtracting the free surface position from the head of mixing zone. The relaxation time of particle velocity is inferred by the exponential fitting of the fastest velocity based on the motion equation of the particle in the planar constant flow. Furthermore, the equivalent diameter of the mixing zone head can also be obtained through the relaxation time. Based on the above methods, the spectrograms of various ejection mixing experiments under different shock-loaded conditions and gas environments are analyzed. The time evolutions of the mixing zone and equivalent diameter are presented, and the effects of shock loading strength and post-shock gas temperature on the mixing zone are analyzed. It is found that the deduced equivalent diameter in gas is smaller than that in vacuum, validating the pneumatic breakup of liquid metal particles in gas.关键词
喷射混合/光子多普勒速度计/速度频谱/等效颗粒度Key words
ejection mixing/photonic Doppler velocimetry/velocity spectrogram/equivalent diameter引用本文复制引用
孙海权,王裴,陈大伟,马东军..一种新的光子多普勒速度频谱分析方法∗[J].物理学报,2016,65(10):208-215,8.基金项目
中国工程物理研究院科学技术发展基金(批准号:2015B0101021,2015B0201043)、计算物理重点实验室基金(批准号:9140C690103150C69302)和国家自然科学基金(批准号：U1530261)资助的课题 （批准号:2015B0101021,2015B0201043）
