Droplet size distribution in a swirl airstream using in-line holography technique

Ade, Someshwar Sanjay and Kirar, Pavan Kumar and Chandrala, Lakshmana Dora and Sahu, Kirti Chandra (2023) Droplet size distribution in a swirl airstream using in-line holography technique. Journal of Fluid Mechanics, 954 (A39). ISSN 0022-1120

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Abstract

We investigate the morphology and size distribution of satellite droplets resulting from the interaction of a freely falling water droplet with a swirling airstream of different strengths by employing shadowgraphy and deep-learning-based digital in-line holography techniques. We found that the droplet exhibits vibrational, retracting bag and normal breakup phenomena for the no swirl, low and high swirl strengths for the same aerodynamic field. In the high-swirl scenario, the disintegrations of the nodes, rim and bag-film contribute to the number mean diameter, resulting in smaller satellite droplets. In contrast, in the low-swirl case, the breakup of the rim and nodes only contributes to the size distribution, resulting in larger droplets. The temporal variation of the Sauter mean diameter reveals that for a given aerodynamic force, a high swirl strength produces more surface area and surface energy than a low swirl strength. The theoretical prediction of the number-mean probability density of tiny satellite droplets under swirl conditions agrees with experimental data. However, for the low swirl, the predictions differ from the experimental results, particularly due to the presence of large satellite droplets. Our results reveal that the volume-weighted droplet size distribution exhibits two (bi-modal) and three (multi-model) peaks for low and high swirl strengths, respectively. The analytical model that takes into account various mechanisms, such as the nodes, rim and bag breakups, accurately predicts the shape and characteristic sizes of each mode for the case of high swirl strength.

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IITH Creators:

IITH Creators	ORCiD
Chandrala, Lakshmana Dora	UNSPECIFIED
Sahu, Kirti Chandra	http://orcid.org/0000-0002-7357-1141

Item Type:

Article

Uncontrolled Keywords:

Breakup/coalescence; Droplet size distributions; In-line holography; Low swirl; Morphology and size; Morphology distributions; Satellite droplets; Shadowgraphy; Size-distribution; Water droplets

Subjects:

Others > Mechanics
Materials Engineering > Materials engineering
Chemical Engineering

Divisions:

Department of Chemical Engineering
Department of Mechanical & Aerospace Engineering

Depositing User:

Mr Nigam Prasad Bisoyi

Date Deposited:

19 May 2023 11:56

Last Modified:

19 May 2023 11:56

URI:

http://raiithold.iith.ac.in/id/eprint/11510