TY - GEN
T1 - Quantification of convection velocity and dominant scale of large-scale structures by high-speed schlieren imaging
AU - Kouchi, Toshinori
AU - Masuya, Goro
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2012
Y1 - 2012
N2 - We proposed a new method to evaluate simultaneously both convective velocity and scale of dominant turbulent structures captured in a high speed framing schlieren movie. We took 90 time-series schlieren images of a transverse jet into a Mach 2 supersonic flow with 1 MHz sampling. We focused on periodical image gradations due to the turbulent structures within the jet and boundary layer. We remapped the image intensities on the structures along their trajectory as a time-space map. The time-space map showed swept stripe patterns. The presence of the stripe patterns indicates stable structures were periodically generated and convected downstream. Slope of the stripes corresponds to the convective velocities of the structures. Cycles in the space- and time-directions of the stripes correspond to the scale and formation cycle of the dominant structure. Two-dimensional Fourier transform efficiently extracted the dominant ones from the time-space map. We demonstrated this newlyproposed method using two-dimensional Fourier transform accurately evaluated the convective velocity and scale of the dominant turbulent structures within the jet and boundary layer.
AB - We proposed a new method to evaluate simultaneously both convective velocity and scale of dominant turbulent structures captured in a high speed framing schlieren movie. We took 90 time-series schlieren images of a transverse jet into a Mach 2 supersonic flow with 1 MHz sampling. We focused on periodical image gradations due to the turbulent structures within the jet and boundary layer. We remapped the image intensities on the structures along their trajectory as a time-space map. The time-space map showed swept stripe patterns. The presence of the stripe patterns indicates stable structures were periodically generated and convected downstream. Slope of the stripes corresponds to the convective velocities of the structures. Cycles in the space- and time-directions of the stripes correspond to the scale and formation cycle of the dominant structure. Two-dimensional Fourier transform efficiently extracted the dominant ones from the time-space map. We demonstrated this newlyproposed method using two-dimensional Fourier transform accurately evaluated the convective velocity and scale of the dominant turbulent structures within the jet and boundary layer.
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U2 - 10.2514/6.2012-4148
DO - 10.2514/6.2012-4148
M3 - Conference contribution
AN - SCOPUS:84947472655
SN - 9781600869358
T3 - 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2012
BT - 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2012
PB - American Institute of Aeronautics and Astronautics Inc.
T2 - 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2012
Y2 - 30 July 2012 through 1 August 2012
ER -