Experimental Study of Primary Atomization Characteristics of Sonic Air-Assist Atomizers

Sikka, Raghav; Vågsæther, Knut; Bjerketvedt, Dag; Lundberg, Joachim

doi:10.3390/app112110444

Cited by 3 publications

(1 citation statement)

References 21 publications

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“…Using a CMOS-based Photron SA-Z high-speed camera, shadowgraph imaging was performed at 21,000 frames per second (fps) with a shutter speed of ∼50 µsec. The experimental setup is explained in more detail (Sikka et al 27 ) The schematic diagram for the shadowgraph setup is shown in Figure 2.…”

Section: Methodsmentioning

confidence: 99%

Atomization characteristics of a bluff body-assisted sonic twin-fluid atomizer

Sikka

Vågsæther

Bjerketvedt

et al. 2022

International Journal of Spray and Combustion Dynamics

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This study examines the gas dynamic effect and atomization behaviour of the sonic bluff body-assisted twin-fluid atomizer with three distinct geometry configurations based on cone distances (Lc) as 6.0 mm, 8.0 mm, and 10.0 mm. The atomization characteristics of these atomizers employing a 280 µm annular liquid sheet with a central bluff body (cone) are compared based on a range of air and liquid flow rates. The spray-bluff body impacted secondary atomization was characterized through volume-normalized droplet size distribution (DSD) & cumulative droplet distribution, excentricity plots, Sauter mean diameter (SMD), and relative span factor (Δ). When plotted for a given liquid flow rate, the DSD & cumulative droplet distribution becomes more uniform with the increase in the airflow rate independent of the cone distance (Lc). Excentricity plots exhibited high excentricity droplets at the spray centreline and a large fraction of nearly spherical droplets at off-centre spray locations. SMD and RSF (Δ) showed opposite trends when plotted against the air-to-liquid ratio (ALR) as SMD increases while RSF decreases with radial locations, respectively. When plotted for all radial locations, Sauter mean diameter (D32) and relative span factor (Δ) show a cluster formation. Larger SMD values correspond to lower RSF (Δ) values and vice-versa.

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Section: Methodsmentioning

confidence: 99%

Atomization characteristics of a bluff body-assisted sonic twin-fluid atomizer

Sikka

Vågsæther

Bjerketvedt

et al. 2022

International Journal of Spray and Combustion Dynamics

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Large-eddy simulation, convective instability, and modal causality of coaxial supersonic air–water jets considering a swirl effect

Weigand

2023

Physics of Fluids

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An annular liquid sheet sheared by a coaxial supersonic gas stream with a swirling effect is investigated using Large Eddy Simulation. Despite its wide applications in aerospace and medical devices, the instability and spatial characters have been barely investigated due to the high complexity under supersonic condition. Unlike the conventional use of the temporal dynamic mode decomposition (DMD), DMD is applied in the axial direction to evaluate the transient convective instability. The high-velocity cases show significantly stronger instability in the nozzle near-field. However, swirling has only marginal effects on the convective instability. In addition, proper orthogonal decomposition (POD) extracts the essential spatial topology of velocity, momentum, and pressure fields. Pulsatile and flapping instabilities are observed in the gas flow, where liquid flow demonstrates the schrink/expansion as well as the flapping instabilities. In addition, all POD modes of the pressure field take the form of coherent wavepacket structures, and their wavelength and spatial forms of the wavepackets are dependent on the gas flow speed rather than the swirling. Time coefficients of the leading POD modes of momentum and pressure fields show an interesting correlation. Hence, the causal–effect relationship between these leading modes of momentum and pressure field is quantified via transfer entropy from the information theory. The transfer entropy from the pressure field to the momentum field is generally higher than vice versa, and this trend is enhanced by the swirling in the low-velocity condition.

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Instability of viscous annular liquid film jet under high air-to-fluid velocity rate

Shi

2024

J. Phys.: Conf. Ser.

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Based on the surface wave dispersion relation equation of viscous annular liquid film jet established by the research group in the early stage, a dispersion relation equation calculation program is written according to Mathematica. A linear stability analysis is carried out for the high air-fluid velocity ratio viscous annular liquid film jet entering a compressible gas medium environment. The relationship between the surface wave growth rate of an annular liquid film jet and the surface wave number under different characteristic parameters is obtained. The connection based on the dominant wave’s growth rate or the dominant wave’s number with dimensionless parameters such as air-fluid velocity rate, air-fluid density rate, Weber number of liquid, liquid Reynolds number, and gas Mach number was analyzed. The consequences reveal that under the high air-fluid velocity ratio, the increase of the above dimensionless parameters promotes the fragmentation course of the annular liquid film jet. Moreover, the augment of the air-fluid velocity rate has the greatest influence on the stability of the viscous annular liquid film jet. In contrast, the Reynolds number of the liquid has less influence than the reliability of the annular liquid film jet. Linear stability analysis under this condition lays the foundation for the prediction model of the most unstable parameters of annular liquid film jet in practical engineering applications.

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Experimental Study of Primary Atomization Characteristics of Sonic Air-Assist Atomizers

Cited by 3 publications

References 21 publications

Atomization characteristics of a bluff body-assisted sonic twin-fluid atomizer

Atomization characteristics of a bluff body-assisted sonic twin-fluid atomizer

Large-eddy simulation, convective instability, and modal causality of coaxial supersonic air–water jets considering a swirl effect

Instability of viscous annular liquid film jet under high air-to-fluid velocity rate

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