Insight into instabilities in burning droplets

Miglani, Ankur and Basu, Saptarshi and Kumar, Ranganathan (2014) Insight into instabilities in burning droplets. In: PHYSICS OF FLUIDS, 26 (3).

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Abstract

The complex multiscale physics of nano-particle laden functional droplets in a reacting environment is of fundamental and applied significance for a wide variety of applications ranging from thermal sprays to pharmaceutics to modern day combustors using new brands of bio-fuels. Formation of homogenous nucleated bubbles at the superheat limit inside vaporizing droplets (with or without nanoparticles) represents an unstable system. Here we show that self-induced boiling in burning functional pendant droplets can produce severe volumetric shape oscillations. Internal pressure build-up due to ebullition activity ejects bubbles from the droplet domain causing undulations on the droplet surface and oscillations in bulk. Through experiments, we establish that the degree of droplet deformation depends on the frequency and intensity of these bubble expulsion events. In a distinct regime of single isolated bubble residing in the droplet, however, pre-ejection transient time is identified by Darrieus-Landau evaporative instability, where bubble-droplet system behaves as a synchronized driver-driven system with bulk bubble-shape oscillations being imposed on the droplet. The agglomeration of nanophase additives modulates the flow structures within the droplet and also influences the bubble inception and growth leading to different levels of instabilities. (C) 2014 AIP Publishing LLC.

Item Type:	Journal Article
Publication:	PHYSICS OF FLUIDS
Publisher:	AMER INST PHYSICS
Additional Information:	Copyright for this article belongs to the AMER INST PHYSICS, USA
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	03 Jun 2014 08:46
Last Modified:	03 Jun 2014 08:46
URI:	http://eprints.iisc.ac.in/id/eprint/49145

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