High-speed 3D reconstruction of liquid surfaces in sprays

article in a collection out of WoS and Scopus

en

Accurately visualizing liquid breakups in sprays is important for a wide range of spray appli- cations as well as for understanding the process of liquid atomization. However, spray data are usually generated either from 2D imaging techniques or using point measurement approaches (using for example Phase Doppler Anemometry – PDA). Relatively few measurements have been performed in 3D which is necessary to obtain the complete characterization of a spray system and to understand how it is formed. In addition, the 3D imaging techniques that are currently available are usually based on time-averaged data and do not have the capability of 3D temporally-resolving fast liquid breakup phenomena. We have developed a novel technique called Fringe Projection – Laser Induced Fluorescence, FP-LIF, with the possibility of gener- ating snapshot 3D surface reconstructions of irregular liquid structures, such as liquid sheets, ligaments, blobs and other large liquid bodies. The advantage of this technique is that only a single camera is used for generating 3D data. In this article we push the technique one step forward by using a Photron SA-Z high-speed camera in order to obtain 3D reconstructions of liquid structures at 20 000 frame per seconds (fps). The technique is applied here for high- speed 3D reconstructions of liquid sheets generated from a pressure swirl atomizer. Such new type of data, presented here, are particularly relevant for the validation and improvement of computational spray models.

Accurately visualizing liquid breakups in sprays is important for a wide range of spray appli- cations as well as for understanding the process of liquid atomization. However, spray data are usually generated either from 2D imaging techniques or using point measurement approaches (using for example Phase Doppler Anemometry – PDA). Relatively few measurements have been performed in 3D which is necessary to obtain the complete characterization of a spray system and to understand how it is formed. In addition, the 3D imaging techniques that are currently available are usually based on time-averaged data and do not have the capability of 3D temporally-resolving fast liquid breakup phenomena. We have developed a novel technique called Fringe Projection – Laser Induced Fluorescence, FP-LIF, with the possibility of gener- ating snapshot 3D surface reconstructions of irregular liquid structures, such as liquid sheets, ligaments, blobs and other large liquid bodies. The advantage of this technique is that only a single camera is used for generating 3D data. In this article we push the technique one step forward by using a Photron SA-Z high-speed camera in order to obtain 3D reconstructions of liquid structures at 20 000 frame per seconds (fps). The technique is applied here for high- speed 3D reconstructions of liquid sheets generated from a pressure swirl atomizer. Such new type of data, presented here, are particularly relevant for the validation and improvement of computational spray models.

High-speed imaging 3D reconstruction liquid surfaces sprays Lasers Imaging Techniques

13.07.2020

Tecnico Lisboa

Lisbon

20th International Symposium on Applications of Laser and Imaging Techniques to Fluid Mechanics 2020

1–9

9