In the literature, the application of sonic anemometry has been limited to low subsonic Mach number, near-incompressible flow conditions. To the best of the authors’ knowledge, this paper represents the first time a sonic anemometry approach has been used to characterize flow velocity beyond Mach 0.3. Using a high speed jet, flow velocity was measured using a modified sonic anemometry technique in flow conditions up to Mach 0.83. A numerical study was conducted to identify the effects of microphone placement on the accuracy of the measured velocity. Based on estimated error strictly due to uncertainty in time-of-acoustic flight, a random error of 4 m s−1 was identified for the configuration used in this experiment. Comparison with measurements from a Pitot probe indicated a velocity RMS error of 9 m s−1. The discrepancy in error is attributed to a systematic error which may be calibrated out in future work. Overall, the experimental results from this preliminary study support the use of acoustics for high subsonic flow characterization.

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An advanced laser-Doppler measurement technique has been developed for fully resolved three-component particle position and velocity vector measurements in turbulent flows. The instrument deemed the ‘comprehensive’ laser-Doppler velocimeter employs a novel optical arrangement to measure multiple-component sub-measurement-volume-scale seed particle positions simultaneously with the velocity vector measurements of conventional laser-Doppler velocimetry (LDV). In the current paper, the effectiveness of the position resolution capabilities is considered, which allows for velocity statistics measurements at multiple locations within the measurement volume. Design estimates for the position vector uncertainties for a particle passing the measurement volume are about 3 µm root mean square in any direction, although in situ estimates indicate an uncertainty value closer to 14 µm with the possibility of further refinement through optimized alignment. To validate the operation of the instrument, measurements are presented in turbulent boundary layers previously examined with high-resolution conventional LDV. The flat-plate turbulent boundary layer is studied at two Reynolds numbers up to Reθ = 7500. Measurements are also presented in a pressure-driven three-dimensional turbulent boundary layer created beside a wing/body junction. These measurements illustrate the effectiveness of the technique for obtaining highly resolved velocity profiles within the measurement volume and give the highest spatial resolution velocity statistics published for Reynolds numbers of the magnitude studied.