Three-Velocity-Component Cross-Correlation Doppler Global Velocimetry for the Space Launch System Booster Separation Test in the NASA Langley Unitary Plan Wind Tunnel

摘要

Three-velocity-component cross-correlation Doppler global velocimetry (CCDGV) developed at Virginia Tech was used to measure spatially-resolved mean flow-field velocities in the Space Launch System Booster Separation Test conducted in the NASA Langley Unitary Plan Wind Tunnel. The flow was probed using a continuous wave, single-frequency laser and imaging was achieved by collecting light scattered by ice particles within the flow Held using fiber optic bundles. The principle of CCDGV was employed by scanning the frequency of the laser over a band of approximately 4 GHz, covering a single optical transmission trough in iodine, which was used as a spectral filter for the measurements. The setup resulted in a spatial resolution of 3.8 mm and 95% confidence velocity uncertainties of ±4%, ±5%, and +1% of the freestream velocity for the streamwise, vertical and horizontal Cartesian velocity components, respectively. Measurements of the freestream showed root-mean-square variations in velocity of about 1%. Particular attention was paid to obtaining measurements between the booster and core when these are in close proximity. The results indicate that this region has a complex, three-dimensional flowfield with substantial velocity gradients due to both the booster separation jets and interactions with the freestream flow.