Time-resolved Doppler global velocimetry (TRDGV) is used to demonstrate three-component velocity measurements of 32 planar points, acquired simultaneously at 250 kHz. Photomultiplier tube arrays are used to detect the flow signal, with each array having eight rows of four pixels. The system utilizes frequency modulation of a continuous wave laser, allowing for simpler calibration of the signals used to determine the incident and Doppler-shifted frequency. The TRDGV system is used to measure an unheated, Mach 0.91 free jet downstream of the potential core collapse. Axial mean velocities were measured within a root-mean-square error of 7 m/s compared to Pitot probe validation measurements. Additionally, axial turbulence intensities showed agreement to hot wire validation measurements and exhibited typical magnitudes reported in the literature. Velocity spectra were obtained for the three components of velocity, revealing a -5/3 decay in the axial velocity spectra in the inertial subrange frequencies, and generally less decay present in the transverse component spectra. Hot wire measurements and spectra from literature were used for validation of the TRDGV spectral results, showing broadband spectral agreement. The instrument described in this work shows promising capability for multi-point, time-resolved velocity vector measurement in high speed compressible flows with acceptable levels of uncertainty.

中文翻译：

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32 个同步点的 250 kHz 三分量多普勒测速：高速流动的新功能

时间分辨多普勒全球测速仪 (TRDGV) 用于演示 32 个平面点的三分量速度测量，在 250 kHz 下同时采集。光电倍增管阵列用于检测流量信号，每个阵列有八行四个像素。该系统利用连续波激光器的频率调制，可以更简单地校准用于确定入射频率和多普勒频移的信号。TRDGV 系统用于测量潜在的岩心坍塌下游的未加热的 0.91 马赫自由射流。与皮托管验证测量相比，轴向平均速度在 7 m/s 的均方根误差内测量。此外，轴向湍流强度与热线验证测量结果一致，并显示出文献中报道的典型量级。获得了速度的三个分量的速度谱，揭示了惯性子范围频率中轴向速度谱的 -5/3 衰减，并且横向分量谱中的衰减通常较小。文献中的热线测量和光谱用于验证 TRDGV 光谱结果，显示宽带光谱一致性。在这项工作中描述的仪器显示了在具有可接受的不确定性水平的高速可压缩流中进行多点、时间分辨速度矢量测量的有希望的能力。文献中的热线测量和光谱用于验证 TRDGV 光谱结果，显示宽带光谱一致性。在这项工作中描述的仪器显示了在具有可接受的不确定性水平的高速可压缩流中进行多点、时间分辨速度矢量测量的有希望的能力。文献中的热线测量和光谱用于验证 TRDGV 光谱结果，显示宽带光谱一致性。这项工作中描述的仪器显示了在具有可接受的不确定性水平的高速可压缩流中进行多点、时间分辨速度矢量测量的有希望的能力。