Detection of second-mode instabilities on a flared cone in Mach 6 quiet flow with linear array focused laser differential interferometry
Detection of second-mode instabilities on a flared cone in Mach 6 quiet flow with linear array focused laser differential interferometry
复制标题
使用线性阵列聚焦激光差分干涉仪检测马赫 6 安静流中扩口锥体的第二模式不稳定性
DOI：
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发表时间：
2021
影响因子：
2.4
通讯作者：
J. Schmisseur
中科院分区：
文献类型：
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作者：
Mark Gragston;Farha Y. Siddiqui;J. Schmisseur
在这项工作中，一种改进的聚焦激光差动干涉仪(FLDI)被用来测量马赫数为6的静流中喇叭锥边界层中的二次模不稳定性。在FLDI系统中增加了一个衍射光学元件，可以提供六束通过单个沃尔拉斯顿棱镜的光束，允许多个测量点，而不需要额外的沃尔拉斯顿棱镜。该技术称为线阵FLDI(LA-FLDI)，用于高超声速边界层中第二模不稳定性的六次同时测量。这是FLDI的这种变化首次用于第二模不稳定性的测量，并表明在传统的FLDI中加入衍射光学元件和光束功率的分割并不排除这种使用。因此，LA-FLDI似乎有很大的潜力来提高高速边界层的测量效率，因为它允许在单个设施运行中在不同位置进行多次测量。估计了二模波包的速度，并进行了双谱分析，结果表明，谐波与二次相位耦合作用有关。
In this work, an enhanced version of the focused laser differential interferometer (FLDI) is used to measure second-mode instabilities in the boundary layer on a flared cone in Mach 6 quiet flow. A diffractive optical element added to the FLDI system provides six beams that pass through a single Wollaston prism, allowing for multiple points of measurements without the need for additional Wollaston prisms. This technique, linear array-FLDI (LA-FLDI), is used for six simultaneous measurements of second-mode instabilities in a hypersonic boundary layer. This is the first time that this variation of FLDI has been used for second-mode instability measurements and demonstrates that the inclusion of a diffractive optical element into the traditional FLDI and splitting of beam power does not preclude such usage. Thus, LA-FLDI appears to have significant potential for increasing the efficiency of measurements of high-speed boundary layers by enabling multiple measurements at different locations within a single facility run. The velocity of the second-mode wavepacket is estimated and a bispectral analysis is presented showing that harmonics are associated with quadratically phased coupled interactions.