A multi-point focused laser differential interferometer for characterizing freestream disturbances in hypersonic wind tunnels
A multi-point focused laser differential interferometer for characterizing freestream disturbances in hypersonic wind tunnels
复制标题
用于表征高超声速风洞中自由流扰动的多点聚焦激光差分干涉仪
DOI：
10.1007/s00348-022-03522-6
复制
发表时间：
2022
影响因子：
2.4
通讯作者：
Laurence, Stuart J.
中科院分区：
文献类型：
--
作者：
Gillespie, Graeme I.;Ceruzzi, Andrew P.;Laurence, Stuart J.
利用三点聚焦激光差动干涉仪(FLDI)对马赫-6激波风洞中的自由流扰动环境进行了研究。FLDI波束被分开，其中一对与流动方向对齐，另一对沿马赫角对准，从而允许同时测量沿着流线传播的熵涨落和沿着马赫线传播的声扰动。将用于解释FLDI信号的传递函数应用于自由射流喷嘴流动：估计了仪器的焦深和对干扰波数的灵敏度，以及喷嘴剪切层对FLDI信号的影响。实验是在不同的单位雷诺数(3.214.410)和总焓(0.570.89 MJ/kg)下进行的。用FLDI测量的流向对流速度低于理论自由流速度，这与以前详细描述噪声对流速度的研究一致，尽管观察到了一些频率相关性。宽频带湍流强度和基于核心流动密度的湍流强度均随雷诺数的增加而减小。通过对相关信号对的研究，还考察了声扰动和熵扰动对整体噪声环境的相对贡献。声学贡献在所有情况下都占主导地位，雷诺数没有明显的变化趋势。最后，对不同风洞条件下的扰动间歇性进行了研究，在最低雷诺数条件下，扰动间歇性最大，表明喷管边界层在该条件下可能是过渡性的。
A three-point Focused Laser Differential Interferometer (FLDI) instrument was implemented to investigate the freestream disturbance environment in a Mach-6 shock tunnel. The FLDI beams were split such that one pair was aligned with the flow direction and the other along the Mach angle, allowing for simultaneous measurements of entropic fluctuations propagating along streamlines and acoustic disturbances along Mach lines. Transfer functions for interpreting the FLDI signal were applied to the free-jet nozzle flow: the instrument’s depth of focus and sensitivity to disturbance wavenumber were estimated, as well as the influence of the nozzle shear layers in corrupting the FLDI signal. Experiments were performed at varying unit Reynolds numbers (3.214.410) and total enthalpies (0.570.89 MJ/kg). Streamwise convection velocities measured with the FLDI were found to be lower than theoretical freestream velocities, consistent with earlier studies detailing the noise convection velocity, though some frequency dependence was observed. Both broadband and core-flow density-based turbulence intensities exhibited a decrease with increasing Reynolds number. The relative contributions of the acoustic and entropic disturbances to the overall noise environment was also examined through a study of the correlated signal pairs. The acoustic contribution was found to be dominant in all cases, with no clear trend with Reynolds number. Finally, the disturbance intermittency at the various tunnel conditions was investigated; the intermittency was greatest at the lowest Reynolds number condition, suggesting that the nozzle boundary layer may be transitional at this condition.
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DOI：
10.2514/6.2017-3631
发表时间：
2017
期刊：
AIAA Scitech 2019 Forum
影响因子：
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作者：
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DOI：
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发表时间：
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期刊：
AIAA SCITECH 2022 Forum
影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
2.4
作者：
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通讯作者：
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