Experimental Study on Secondary Breakup of Droplets at Low Density Ratios

Prakash, SR and Boggavarapu, P and Ravikrishna, RV (2021) Experimental Study on Secondary Breakup of Droplets at Low Density Ratios. In: UNSPECIFIED.

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Abstract

Secondary breakup of droplets has been extensively studied to understand the mechanism of disintegration of droplets subjected to aerodynamic forces. Most of the experimental studies involve density ratios (R = �liq / �gas) greater than 500. However, the practical engine sprays encounter R < 100. On the other hand, some of the numerical investigations are carried out at R < 50. Thus, the current study aims to conduct single drop breakup experiments at density ratios < 500 to fill gaps in the literature. The experiments are performed in a high-pressure chamber (� 10 bar) with optical access which houses both the mono-disperse drop generator and a contoured nozzle to produce the required air jet. Elevating the chamber pressure to 10 bar results in lower R (up to ~75) and the aerodynamic Weber number (We) is varied by controlling the air jet velocity. Two different liquids and drop sizes are employed to verify the veracity of the observed results. It is observed that a lower density ratio causes the critical Weber number to have a slightly lower magnitude (We ~ 9.4) resulting in earlier disintegration of droplets. All the breakup regimes observed at atmospheric pressure are also observed at lower density ratios. A new breakup structure is observed to occur intermittently along with bag and bag-stamen breakup modes in the form of �reverse-hat�. As the density ratio reduces the mode-changeovers are observed to occur at lower Weber numbers. On a log-log graph of density ratio vs. Weber number, the reduction in mode-changeover Weber number reduces almost linearly. The present study has thrown more light on the effect of low density ratios on secondary breakup, parts of which have been grey areas in the existing literature. © 2021 ICLASS 2021 - 15th Triennial International Conference on Liquid Atomization and Spray Systems. All Rights Reserved.

Item Type:	Conference Paper
Publication:	ICLASS 2021 - 15th Triennial International Conference on Liquid Atomization and Spray Systems
Publisher:	ILASS - Europe, Institute for Liquid Atomization and Spray Systems
Additional Information:	The copyright for this article belongs to The university of Edinburg
Keywords:	Aerodynamics; Atmospheric pressure; Disintegration; Drop breakup; Jets, 'current; Aerodynamic forces; Air jet; Breakup regimes; Density ratio; High pressure; Lower density; Numerical investigations; Secondary breakup; Weber numbers, Atomization
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	04 Mar 2024 05:18
Last Modified:	04 Mar 2024 05:18
URI:	https://eprints.iisc.ac.in/id/eprint/84098

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