3D surface reconstruction of liquid structures in sprays using structured illumination and phase demodulation

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The accurate surface reconstruction of 3D liquid structures is an important aspect for the understanding of
spray formation and liquid breakups. In this article, an approach to image in 3D the surface of liquid structures
in sprays (such as ligaments, liquid sheets/cores and liquid blobs) is presented. The technique is named Fringe
Projection - Laser Induced Fluorescence (FP-LIF) which is used by illuminating the liquid structures using a
laser interference fringe projection. By doping, at high concentration, the injected liquid with a fluorescent
dye (here fluorescein) a fluorescence signal can be generated very close to the liquid surface. Then, this signal
is recorded at a backward angle where the incident modulation encodes the information of the third surface
coordinate for each pixel. The recorded 2D images are phase demodulated using the Continuous Wavelet
Transform (CWT) and the 3D surface coordinates can be retrieved. In the first part of the presented work,
simulated liquid surfaces are considered for parameter optimization of the 3D reconstruction and to evaluate
the CWT implementation. It is found from the simulated results that the optimum fringe projection period
sampling is 4 − 7 pixels. In the second part, the technique is applied for two experimental cases of a pending
drop and for an onion shaped liquid sheet. To conclude, both the simulated and experimental results show
promising 3D reconstructions of liquid surfaces providing a new type of data, which in the future can be used
for the validation of computational models simulating liquid breakup.


Enheter & grupper
Titel på värdpublikationILASS–Europe 2019, Proceedings of the 29th Conference on Liquid Atomization and Spray Systems, 2-4 September 2019, Paris, France
StatusPublished - 2019 sep 2
Peer review utfördJa