Drift of Droplets from Air-Induction Nozzles

2019 ◽  
Vol 62 (6) ◽  
pp. 1683-1687
Author(s):  
Scott L. Post
Keyword(s):  
Aerodynamic Drag ◽  
Numerical Models ◽  
Liquid Sheet ◽  
Pure Liquid ◽  
Liquid Density ◽  
Liquid Droplets ◽  
Pesticide Application ◽  
Spray Density ◽  
Droplet Sizes ◽  
Moving Liquid

Abstract. For more than 20 years, air-induction or air-inclusion (AI) nozzles have had increased use for pesticide application due to their drift reduction capabilities. The pressure drop created by the pre-orifice and the venturi chamber results in a slower-moving liquid sheet exiting the main orifice, which in turn results in larger droplet sizes, which are less prone to drift. However, two additional factors somewhat mitigate the advantage of larger droplets from AI nozzles: the lower initial spray jet momentum from AI nozzles (compared to standard nozzles of the same flow rating at the same pressure) means that droplets from AI nozzles are more affected by lateral crosswind, and the lower effective liquid density of droplets from AI nozzles due to the presence of air inclusions means that AI droplets are more affected by aerodynamic drag than pure liquid droplets of comparable sizes from standard nozzles. In this work, theoretical and numerical models are developed to quantify these effects and develop tools for accurate drift prediction from sprayers using AI nozzles. The reduction in spray density due to the presence of air inclusions is in the range of 12% to 36%. This reduction in density affects the aerodynamic drift of the spray droplets, with the result that a droplet with 30% air inclusions would have the drift characteristics of a normal droplet with 20% smaller diameter. HighlightsSprays from air induction (AI) nozzles typically contain 12% to 36% air inclusions by volume.A droplet with 30% air inclusions would have the same drift characteristics as a water droplet of 20% smaller diameter.An analytical model is developed to predict the drift distances of small droplets. Keywords: Air induction, Droplet size, Nozzles, Pesticides, Sprayers.

Nucleation During the Solidification of Atomized Droplets Catalyzed by Spherically-Shaped Oxide Particles

1986 ◽  
Vol 80 ◽  
Author(s):  
Matthew R. Libera ◽  
Gregory B. Olson ◽  
John B. Vander Sande
Keyword(s):  
Oxide Particle ◽  
Rare Earth Oxide ◽  
Pure Liquid ◽  
Liquid Droplets ◽  
Particle Size Distributions ◽  
Pure Liquid Iron ◽  
Droplet Sizes ◽  
Oxide Substrate ◽  
Oxide Particles ◽  
Substrate Particle

AbstractNucleation temperatures are calculated for the case of solidification in atomized metal droplets where spherical substrate particles act as nucleation catalysts. Following the method of Fletcher, the effect of substrate size on catalytic potency is illustrated, and the model is applied to the nucleation of bcc solid from pure, liquid iron containing oxide substrate particles as catalysts. Supercooling data from the literature are used to determine wetting angles for alumina, silica, and rare-earth oxide. Oxide particle-size distributions are then used to predict the supercooling behavior of atomized liquid droplets based on the probability that a given size of droplet will contain a particular size of substrate particle. A transition size regime is found separating droplet sizes undergoing very small and very large supercoolings, respectively. This is discussed in terms of the types and number densities of inclusions present during atomization of the melt.

Nonlinear instability of plane liquid sheets

2000 ◽  
Vol 406 ◽  
pp. 281-308 ◽  
Author(s):  
SEYED A. JAZAYERI ◽  
XIANGUO LI
Keyword(s):  
Weber Number ◽  
Density Ratio ◽  
Perturbation Expansion ◽  
Liquid Sheet ◽  
Fundamental Wave ◽  
Liquid Density ◽  
Initial Amplitude ◽  
Nonlinear Stability Analysis ◽  
Liquid Sheets ◽  
Breakup Time

A nonlinear stability analysis has been carried out for plane liquid sheets moving in a gas medium at rest by a perturbation expansion technique with the initial amplitude of the disturbance as the perturbation parameter. The first, second and third order governing equations have been derived along with appropriate initial and boundary conditions which describe the characteristics of the fundamental, and the first and second harmonics. The results indicate that for an initially sinusoidal sinuous surface disturbance, the thinning and subsequent breakup of the liquid sheet is due to nonlinear effects with the generation of higher harmonics as well as feedback into the fundamental. In particular, the first harmonic of the fundamental sinuous mode is varicose, which causes the eventual breakup of the liquid sheet at the half-wavelength interval of the fundamental wave. The breakup time (or length) of the liquid sheet is calculated, and the effect of the various flow parameters is investigated. It is found that the breakup time (or length) is reduced by an increase in the initial amplitude of disturbance, the Weber number and the gas-to-liquid density ratio, and it becomes asymptotically insensitive to the variations of the Weber number and the density ratio when their values become very large. It is also found that the breakup time (or length) is a very weak function of the wavenumber unless it is close to the cut-off wavenumbers.

scholarly journals 2D and 3D numerical modelling of internal flow of Pressure-swirl atomizer

2019 ◽  
Vol 213 ◽  
pp. 02055
Author(s):  
Milan Maly ◽  
Jaroslav Slama ◽  
Marcel Sapik ◽  
Jan Jedelsky
Keyword(s):  
Numerical Models ◽  
Internal Flow ◽  
Liquid Sheet ◽  
Spray Cone ◽  
Air Core ◽  
Swirl Velocity ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
2D And 3D ◽  
Pressure Swirl Atomizer

This paper compares 2D axisymmetric and 3D numerical models used to predict the internal flow of a pressure-swirl atomizer using a commercial software Ansys Fluent 18.1. The computed results are compared with experimental data in terms of spray cone angle (SCA), discharge coefficient (CD), internal air-core dimensions and swirl velocity profile. The swirl velocity was experimentally studied using a Laser Doppler Anemometry in a scaled transparent model of the atomizer. The internal air-core was visualized at high temporal and spatial resolution by a high-speed camera with backlit illumination. The internal flow was numerically treated as transient two-phase flow. The gas-liquid interface was captured with Volume of Fluid scheme. The numerical solver used both laminar and turbulent approach. Turbulence was modelled using k-ε, k-ω, Reynolds Stress model (RSM) and coarse Large Eddy Simulation (LES). The laminar solver was capable to predict all the parameters with an error less than 5% compared with the experimental results in both 2D and 3D simulation. However, it overpredicted the velocity of the discharged liquid sheet. The LES model performed similarly to the laminar solver, but the liquid sheet velocity was 10% lower. The two-equation models k-ε and k-ω overpredicted the turbulence viscosity and the internal air-core was not predicted.

Linear stability analysis of an electrified incompressible liquid sheet streaming into a compressible ambient gas

2016 ◽  
Vol 231 (10) ◽  
pp. 1849-1858 ◽  
Author(s):  
Yuxin Liu ◽  
Chaojie Mo ◽  
Lujia Liu ◽  
Qingfei Fu ◽  
Lijun Yang
Keyword(s):  
Stability Analysis ◽  
Electric Field ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Density Ratio ◽  
Sheet Thickness ◽  
Liquid Sheet ◽  
Wave Number ◽  
Liquid Density ◽  
Ambient Gas

This article presents the linear stability analysis of an electrified liquid sheet injected into a compressible ambient gas in the presence of a transverse electric field. The disturbance wave growth rates of sinuous and varicose modes were determined by solving the dispersion relation of the electrified liquid sheet. It was determined that by increasing the Mach number of the ambient gas from subsonic to transonic, the maximum growth rate and the dominant wave number of the disturbances were increased, and the increase was greater in the presence of the electric field. The electrified liquid sheet was more unstable than the non-electrified sheet. The increase of both the gas-to-liquid density ratio and the electrical Euler number accelerated the breakup of the liquid sheet for both modes; while the ratio of distance between the horizontal electrode and the liquid-sheet-to-sheet thickness had the opposite effect. High Reynolds and Weber numbers accelerated the breakup of the electrified liquid sheet.

Modeling the Effects of Various Liquid Droplet Sizes in Acoustic Deliquification Techniques

2021 ◽  
Author(s):  
Eiman Al Munif ◽  
Ahmed Alrashed ◽  
Kanat Karatayev ◽  
Jennifer Miskimins ◽  
Yilin Fan
Keyword(s):  
Fluid Dynamics ◽  
Natural Gas ◽  
Computational Time ◽  
Liquid Droplets ◽  
Gas Wells ◽  
Air Velocity ◽  
Liquid Loading ◽  
Artificial Lift ◽  
Tool Surface ◽  
Droplet Sizes

Abstract Liquid loading is a major challenge in natural gas wells. Enhancing the production in liquid loading natural gas wells using an acoustic liquid atomizer tool is proposed as a possible artificial lift method. The effect of different droplet sizes on the transport efficiency and the performance of the proposed technique during production are studied using Computational Fluid Dynamics (CFD) simulation. Also, the liquid behavior and fluid dynamics after applying the atomization mechanism are reviewed. In the model, the tool is placed axially in the middle of the gas/air flowing wellbore. To reduce computational time, the tool and pipe are cut symmetrically. The pipe diameter is 4 in, and the four injectors diameters are each 0.04 in. The orientation of the injectors is set to 90° with the sprayers facing sideways, while water liquid droplets are injected from the tool surface into the air flow at angles from 45° to the flow direction. Unstructured hybrid mesh is used to allow the cells to assemble freely within the complex geometry. Sensitivity tests were conducted with droplet sizes ranging between 30-300 µm. The CFD results showed that water liquid droplets of size 30 µm followed the pathway along the tool surface due to the low mass of the droplets and high air velocity. This phenomenon is called wall impingement and occurs where the droplets are very small and clustering on the wall. The 200 and 300 µm water liquid droplets kept their inertial high chaotic movements in all directions within the computational fluid domain due to the increased weight of the droplets. These larger sized droplets withstand the backpressure from high turbulent air velocity and tend to keep their inertial turbulent movement. This research presents a set of CFD results to further evaluate acoustic atomization as a possible artificial lift technique. This technique has never been commercially applied in the oil and gas industry, and continued evaluation of such methods is a vital addition to the industry as it brings the potential for new lower cost artificial lift technologies. If completely developed, this technique can bring a cost-effective solution compared to conventional artificial lift methods.

Instability of a moving liquid sheet in the presence of acoustic forcing

2010 ◽  
Vol 22 (2) ◽  
pp. 022101 ◽  
Author(s):  
Aditya S. Mulmule ◽  
Mahesh S. Tirumkudulu ◽  
K. Ramamurthi
Keyword(s):  
Liquid Sheet ◽  
Acoustic Forcing ◽  
Moving Liquid

Linear Instability of Liquid Sheets Subjected to a Transverse Electric Field

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Xiao Cui ◽  
Qing-Fei Fu ◽  
Lijun Yang ◽  
Luo Xie ◽  
Bo-Qi Jia
Keyword(s):  
Growth Rate ◽  
Liquid Sheet ◽  
Linear Instability ◽  
Wave Number ◽  
Perfect Conductor ◽  
Liquid Density ◽  
Dielectric Model ◽  
Leaky Dielectric Model ◽  
Leaky Dielectric ◽  
Gas To Liquid

Abstract A temporal linear instability analysis was performed for a liquid sheet moving around the inviscid gas in transverse electrical field. The fluid was described by the leaky-dielectric model, which is more complex and more comparable to the liquid electrical properties than existing models. As a result, the sinuous and the varicose modes exist, in which the dimensionless dispersion relation between wave number and temporal growth rate can be derived as a 3 × 3 matrix. According to this relationship, the effects of liquid properties on sheet instability were performed. It was concluded that, as the electrical Euler number (Eu), the ratio of gas-to-liquid density (ρ), Weber number (We), Reynolds number (Re), and the relative relaxation time (τ) increased, the instability of the sheet was enhanced. This work also compared the leaky-dielectric model with the perfect conductor model and found that the unstable growth rate in the leaky-dielectric model was higher than the one in the perfect conductor model. Moreover, as the ratio of gas-to-liquid improved, this difference decreased. Finally, an energy approach was adopted to investigate the instability mechanism for the two models.

Absolute and convective instability of a liquid sheet

1990 ◽  
Vol 220 ◽  
pp. 673-689 ◽  
Author(s):  
S. P. Lin ◽  
Z. W. Lian ◽  
B. J. Creighton
Keyword(s):  
Weber Number ◽  
Convective Instability ◽  
Density Ratio ◽  
Sheet Thickness ◽  
Surface Tension Force ◽  
Liquid Sheet ◽  
Inertia Force ◽  
Liquid Density ◽  
Gas To Liquid ◽  
Density Ratios

The linear stability of a viscous liquid sheet in the presence of ambient gas is investigated. It is shown that there are two independent modes of instability, sinuous and varicose. The large-time asymptotic amplitude of sinuous disturbances is found to be bounded but non-vanishing for all calculated values of Reynolds numbers and the gas-to-liquid density ratios when the Weber number is greater than one half. The Weber numberWeis defined as the ratio of the surface tension force to the inertia force per unit area of the gas–liquid interface. WhenWeis smaller than one half, the sinuous mode is stable if the gas-to-liquid density ratio is zero, otherwise it is convectively unstable. The varicose mode is always convectively unstable unless the density ratio,Q, is zero. Then it is asymptotically stable. The spatial growth rate of the varicose mode is smaller than that of the sinuous mode for the same flow parameters. The wavelength of the most amplified waves in both modes is found to scale with the product of the sheet thickness andQ/We. It is shown, by use of the energy equation, that the mechanism of instability is a capillary rupture whenWe[ges ] 0.5, and the convective instability is due to the interfacial pressure fluctuation whenWe< 0.5.

The Properties of Liquid Phase Embryos at the Intersections of Plane Solid Surfaces

1952 ◽  
Vol 5 (4) ◽  
pp. 618
Author(s):  
RG Wylie
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Boundary Line ◽  
Pure Liquid ◽  
Liquid Droplets ◽  
Free Energies ◽  
Different Types ◽  
Kinetics Of

In order to calculate the probabilities of nucleation of liquid droplets at different types of site on a solid surface, the properties of embryonic droplets which may exist in complete thermodynamic equilibrium at those sites must be known. The general properties of liquid embryos formed on a plane solid surface, or at lines or points of intersection of plane solid surfaces, are considered. It is shown that, although an edge free energy associated with the boundary line may substantially affect the properties -of embryos at small contact angles, the effect is probably not large, for embryos of the sizes of interest, when the contact angle is larger than about π/4. The areas, volumes, total surface free energies, and free energies of formation are found for embryos at these sites as functions of the contact angle, any edge free energies being neglected. The extension to the formation of bubbles at plane solid surfaces in a pure liquid is indicated. The results are applied in a following paper to the kinetics of condensation of a vapour at an imperfect crystalline surface.

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