Modes of atomization in biofuel droplets induced by a focused laser pulse. (1st May 2022)

• Record Type: Journal Article
• Authors: Jagadale, Vishal S.; Rao, D. Chaitanya Kumar; Deshmukh, Devendra; Hanstorp, Dag; Mishra, Yogeshwar Nath
• Is Part Of: Fuel. Volume 315(2022)
• Publication Date: 2022-05-01
• Subjects: Biofuels -- Droplet atomization -- Nanosecond laser -- Ligament-mediated breakup; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.123190
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: Three distinct breakup modes in biofuel droplets are induced by a focused nanosecond laser pulse. The dominant modes of breakup are via air entrapment, sheet breakup, and catastrophic breakup. The RME-Ethanol emulsions undergo efficient fragmentation compared to pure liquid droplets. Abstract: Single droplet fragmentation of different liquids is essential for the fundamental understanding and augmenting of the atomization process involved in several industrial processes. Most importantly, there is a need to increase our understanding of the atomization of biofuels in combustion devices such as gas turbines and internal combustion engines. In this work, we describe and compare the laser-induced fragmentation of ethanol, Rapeseed Methyl Ester (RME), and their emulsions. We use a nanosecond laser pulse of various laser energies to fragment droplets. Acoustic levitation is used for non-contact manipulation of an isolated single droplet, and the fragmentation sequences are recorded using two high-speed cameras. Three breakup modes are observed: Droplet rupture and air entrapment, sheet breakup, and prompt/catastrophic fragmentation. At lower laser energy, air entrapment inside the droplet occurs. Sheet breakup and catastrophic breakup are observed for droplets of RME emulsions. The ligament-mediated atomization via Rayleigh-Plateau instability and the resulting secondary droplets are studied in detail. The breakup of RME-Ethanol emulsions results in the formation of small secondary droplets compared to pure liquid droplets.