Liquid jet breakup and spray formation with annular swirl air

Soni, Surendra Kumar; Kolhe, Pankaj

doi:10.1016/j.ijmultiphaseflow.2020.103474

Cited by 23 publications

(10 citation statements)

References 51 publications

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“…on the right-hand side of the swirler, the droplet experiences a co-flow configuration (as indicated by the downward velocity vectors in figure 9e-h). As noted in the introduction, a few researchers have previously used high-speed photography and PIV techniques to explore the features of swirl flow from a nozzle, albeit without droplets (Merkle et al 2003;Rajamanickam & Basu 2017;Kumar & Sahu 2019;Patil & Sahu 2021;Soni & Kolhe 2021). They also reported a similar flow field.…”

Section: Droplet Trajectorymentioning

confidence: 98%

“…The critical Weber numbers (transition from vibrational to bag breakup) in various configurations, as reported in earlier investigations. Kumar & Sahu 2019;Patil & Sahu 2021;Soni & Kolhe 2021), however, have examined the characteristics of swirl flow in the absence of droplets using high-speed imaging and particle image velocimetry (PIV) techniques.…”

Section: Introductionmentioning

confidence: 99%

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An experimental investigation of droplet morphology in swirl flow

et al. 2022

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The interaction of a droplet with a swirling airstream is investigated experimentally using shadowgraphy and particle image velocimetry techniques. In swirl flow, the droplet experiences oppose-flow, cross-flow and co-flow conditions depending on its ejection location, the velocity of the airstream and the swirl strength, which results in distinct droplet morphologies as compared with the straight airflow situation. We observe a new breakup phenomenon, termed as ‘retracting bag breakup’, as the droplet encounters a differential flow field created by the wake of the swirler's vanes and the central recirculation zone in swirl airflow. A regime map demarcating the various modes, such as no breakup, vibrational breakup, retracting bag breakup and bag breakup modes, is presented for different sets of dimensionless parameters influencing the droplet morphology and its trajectory. In contrast to the straight flow, the swirl flow promotes the development of the Rayleigh–Taylor instability, enhancing the stretching factor in the droplet deformation process, resulting in a larger number of fingers on the droplet's surface. In order to gain physical insight, a modified theoretical analysis based on the Rayleigh–Taylor instability is proposed for the swirl flow. The experimental behaviour of droplet deformation phenomena in swirl flow conditions can be determined by modifying the stretching factor in the theoretical model.

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Section: Droplet Trajectorymentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

An experimental investigation of droplet morphology in swirl flow

et al. 2022

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“…Moreover, to our knowledge, no one has previously investigated the droplet size distribution under swirl airstream, even though such a situation is frequently encountered during rainfall (Lewellen, Lewellen & Xia 2000; Haan et al. 2017) and in many industrial applications (Soni & Kolhe 2021; Candel et al. 2014).…”

Section: Introductionmentioning

confidence: 99%

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

Ade

Kirar²,

Chandrala³

et al. 2023

J. Fluid Mech.

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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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“…This distance is characterised by the breakup length and the magnitude of this parameter closely relates to the characteristics of the spray. The parameters involved are discussed by Soni and Kolhe [9]. The nozzle of an injector can have different shapes.…”

Section: Introductionmentioning

confidence: 99%

Modelling and Validating the Spray Characteristics of a Co-axial Twin-Fluid Atomizer Using OpenFOAM

Sathishkumar

Rao

Pradeep

et al. 2022

ARFMTS

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Today, the applications of sprays cover a wide range of fields. Their role in internal combustion engines is instrumental in maintaining higher engine efficiency. A deeper understanding of the liquid-gas phase interaction in sprays is crucial to the atomization process. The methods and models used in the simulations have their challenges due to the various discretization schemes and solutions used. To develop and validate the computational models, well defined experimental data is required. In the present work, spray characteristics were studied numerically through OpenFOAM. As the spray characteristics are closely linked with the liquid breakup length, this study focuses on the primary breakup phenomena and the breakup length of the liquid jet emanating from the twin-fluid co-axial flow atomizer. Numerical simulations were performed for a wide range of initial conditions and the breakup length of the spray was validated against the experimental observed by Sivadas et al., [26]. These simulations were carried out using a Eulerian based VOF solver that models the fluid as a continuum. K-Epsilon model was used to predict the turbulent nature of the spray. The air and water velocities were varied between 19.0 to 31.3 m/s and 0.7 to 1.8 m/s respectively. The proposed model was able to predict the computed breakup length within 20% of the experimental values. The present model can be further extended to test for a co-axial swirl injector to predict finer spray formation.

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Liquid jet breakup and spray formation with annular swirl air

Cited by 23 publications

References 51 publications

An experimental investigation of droplet morphology in swirl flow

An experimental investigation of droplet morphology in swirl flow

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

Modelling and Validating the Spray Characteristics of a Co-axial Twin-Fluid Atomizer Using OpenFOAM

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