Two-component Doppler-shift fluorescence velocimetry applied to a generic planetary entry probe model |
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Authors: | Robert Hruschka Sean O’Byrne Harald Kleine |
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Institution: | (1) School of Engineering and Information Technology, University of New South Wales, Australian Defence Force Academy, Canberra, ACT, 2600, Australia |
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Abstract: | This study discusses the development and application of planar laser-induced fluorescence of nitric oxide (NO PLIF) to measure
velocities in an axisymmetric hypersonic near-wake flow field around a model planetary-entry vehicle configuration. Shapes
and positions of NO spectral lines at every location in the flow are determined over several successive shock tunnel runs.
The lines experience Doppler shifts proportional to the local flow velocity component in the direction of the fluorescence-generating
laser. A Gaussian line shape function is then fitted to the acquired wavelength-dependent fluorescence measurements, the line
center of which is correlated to the time-averaged velocity at each pixel location. The flow field is probed successively
by a laser in two orthogonal directions, which yields the velocity magnitude and direction everywhere in the illuminated plane.
The accuracy of the measurement technique is discussed, and various strategies to characterize systematic errors are presented.
The variation of random uncertainties in different regions of the flow field provides information about the local steadiness
of the flow. To the authors’ knowledge, the measurements represent the first two-component velocity map of a hypersonic near-wake
flow. |
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Keywords: | |
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