Two-photon fluorescence laser sheet imaging for analyzing turbid two-phase flows: Application to transient atomizing sprays

Berrocal E, Miranda M, Conrad C, Püls J, Arnold CL, Wensing M, Linne M (2018)


Publication Language: English

Publication Type: Conference contribution, Conference Contribution

Publication year: 2018

Event location: Lisbon

ISBN: 978-989-20-9177-8

Abstract

In this article we present the use of two-photon excitation laser induced fluorescence (2p-LIF) for imaging through optically dense two-phase flow systems. The main advantage of the approach is that a low level of unwanted
fluorescence signal originating from multiple light scattering is generated. This leads to high visibility and image
contrast even through optically dense media, thus, providing faithful descriptions of the imaged fluid structures.
While 2p-LIF imaging is a well-known point measurement approach in the field of life science microscopy [1], it has,
to the best of the authors’ knowledge, never been tested for observing atomizing sprays. We take advantage of this
process, here, at a macroscopic scale by imaging a light sheet of ~1cm height. To generate enough 2p-LIF signal at
such large scale and for single-shot detection, ultra-short laser pulses of high pulse energy are needed. This is
obtained by using a laser system providing 25 fs pulses centered at 800 nm wavelength and having 2.5 mJ pulse
energy. The technique is demonstrated by imaging a single spray plume from a 6 hole commercial Gasoline Direct
Injection (GDI) system running at 200 bar injection pressure. The injected liquid is water mixed with Fluorescein
dye. We show the important image contrast improvement of 2p-LIF light sheet imaging in comparison with the
traditional shadowgraphy and laser sheet Mie scattering. The proposed approach seems to be promising as a future
tool for detailed analysis of complex turbid two-phase flows systems.

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How to cite

APA:

Berrocal, E., Miranda, M., Conrad, C., Püls, J., Arnold, C.L., Wensing, M., & Linne, M. (2018). Two-photon fluorescence laser sheet imaging for analyzing turbid two-phase flows: Application to transient atomizing sprays. In Proceedings of the 19th International Symposium on Applications of Laser and Imaging Techniques to Fluid Mechanics. Lisbon.

MLA:

Berrocal, Edouard, et al. "Two-photon fluorescence laser sheet imaging for analyzing turbid two-phase flows: Application to transient atomizing sprays." Proceedings of the 19th International Symposium on Applications of Laser and Imaging Techniques to Fluid Mechanics, Lisbon 2018.

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