KHz-rate velocity measurements using pulse-burst, cross-correlation Doppler global velocimetry

Abstract Pulse-burst, cross-correlation Doppler global velocimetry was used to perform kHz-rate velocity measurements in the NASA Langley 4-Foot Supersonic Unitary Plan Wind Tunnel. Planar, one component (2D-1C) velocity measurements were made at rates up to 6 kHz in a canonical, oblique shockwave flowfield, generated by a full-span splitter plate in a Mach 2.4 flow. Assessment of the velocimetric accuracy indicates agreement with theoretical velocity values to within 1-percent on average for all measurements tested. The spatial velocity precision is measured to be between 0.3 and 0.5% (1 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> ) for all tested frequencies, while the ensemble (1 σ ) precision of the measurements was within 2.3% of the measured velocities. Measurement uncertainties that were estimated using Monte Carlo simulations exhibit values similar to the precision (2%) and also indicate the potential for biases in the velocity results as a result of periodic or modal behavior in flows. While these results are promising, the technique also shows great potential for expansion, both in measurement rates and applicability to other techniques.