The Quiet Flows The Don

[Elfreda Barrick]

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Measured and computed surface pressure spectra 0.752 m downstream of the nose tip. The thick black line corresponds to the PCB measurement, and the colored lines correspond to the linear amplification of computed planar and oblique waves at different azimuthal wave numbers, m. Re=11.5106/m.

Measured PCB integrated fluctuation amplitudes compared to computed surface pressure N factors. The measured fluctuations are integrated between 100 and 150 kHz, while the computed N factors were at 120 kHz.

Illustration of bubble size estimation methods overlaid on composite schlieren image at Re=11.7106/m. The orange dots represent the estimated separation and reattachment points found by extrapolating the separation and reattachment shocks to the shear layer, and the yellow dots represent those found by extrapolating the shear layer to the model surface. The separation point for both methods is in approximately the same location for this case. Flow is from left to right.

Composite schlieren images at Re=11.7106/m and Re=2.55106/m highlighting variation in bubble size at different unit Reynolds numbers. Estimated reattachment positions are circled in red. Flow is from left to right.

Consecutive frame differences for schlieren images taken at 20 000 frames per second under both conventional noise and quiet flow. The shear layer is laminar for both cases. Flow is from left to right.

Measured and computed surface pressure spectra on the cone, 0.387 m downstream of the nose tip. The vertical axis has been expanded to show the first mode from the computations. Re=11.5106/m; data are from Paredes et al. [31].

Measured and computed surface pressure spectra along the cone 0.606 m downstream of the nose tip. The thick black line corresponds to the PCB measurement, and the colored lines correspond to the linear amplification of computed planar and oblique waves at different azimuthal wave numbers, m. Re=11.5106/m; data are from Paredes et al. [31].

FLDI density gradient fluctuation PSDs for Re=11.5106/m. Only second-mode waves can be seen in the shear layer at the compression corner. The shear-layer traveling waves start to rise up from the noise floor in measurements taken in the downstream portion of the shear layer. Distances in the legends correspond to heights off the surface. (a) 0.526 m downstream (at compression corner), (b) 0.577 m downstream (just upstream of reattachment), and (c) 0.606 m downstream (just downstream of reattachment).

Plasma perturber pulse samples and FFTs. Pulses were generated at atmospheric pressure without flow to see a high-resolution image of the shape, while lower-resolution data were captured during each run.

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