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

Atomization of acoustically forced liquid sheets

2019 ◽  
Vol 880 ◽  
pp. 653-683 ◽  
Author(s):  
Sandip Dighe ◽  
Hrishikesh Gadgil
Keyword(s):  
Acoustic Field ◽  
Cutoff Frequency ◽  
Liquid Sheet ◽  
Liquid Jets ◽  
Liquid Sheets ◽  
Aerodynamic Interaction ◽  
Transverse Acoustic ◽  
External Acoustic Field ◽  
Acoustic Forcing ◽  
Sheet Breakup

Atomization of a smooth laminar liquid sheet produced by the oblique impingement of two liquid jets and subjected to transverse acoustic forcing in quiescent ambient is investigated. The acoustic forcing perturbs the liquid sheet perpendicular to its plane, thereby setting up a train of sinuous waves propagating radially outwards from the impingement point. These sheet undulations grow as the wave speed decreases towards the edge of the sheet and the sheet characteristics, like intact length and mean drop size, reduce drastically as compared to the natural breakup. Our observations show that the effect of the acoustic field is perceptible over a continuous range of forcing frequencies. Beyond a certain forcing frequency, called the cutoff frequency, the effect of the external acoustic field ceases. The cutoff frequency is found to be an increasing function of the Weber number. Our measurements of the characteristics of spatially amplifying sinuous waves show that the instabilities responsible for the natural sheet breakup augment in the presence of external forcing. Combining the experimental observations and measurements, we conclude that the linear theory of aerodynamic interaction (Squire’s theory) (Squire, Brit. J. Appl. Phys., vol. 4 (6), 1953, pp. 167–169) predicts the important features of this phenomenon reasonably well.

Liquid sheet instability in the presence of acoustic forcing

2007 ◽  
Author(s):  
Aditya Sanjay Mulmule ◽  
Mahesh Tirumkudulu ◽  
N Ananthkrishnan ◽  
K Ramamurthy
Keyword(s):  
Liquid Sheet ◽  
Acoustic Forcing

Effect of Weber Number on Disintegration of Liquid Sheet With Co-Flowing Gas

2014 ◽  
Author(s):  
Mohammad Ali ◽  
Mohammed S. Mayeed ◽  
A. K. M. Sadrul Islam ◽  
M. Quamrul Islam
Keyword(s):  
Weber Number ◽  
Gaseous Medium ◽  
Normal Force ◽  
Surface Force ◽  
Liquid Sheet ◽  
Navier Stokes ◽  
Stokes Systems ◽  
Sheet Breakup ◽  
Surface Tension Forces ◽  
Moving Liquid

The disturbances on the surface of a moving liquid sheet in a moving gaseous medium are studied to analyze the dynamics and breakup of the liquid sheet with co-flowing gas. The problem, composed of the Navier-Stokes systems associated with surface tension forces, is solved by the Volume of Fluid (VOF) technique with a Continuum Surface Force (CSF) manner artificially smoothing the discontinuity present at the interface. The investigation provides the insights into the dynamics and breakup processes. The inlet velocities of liquid and gas are determined by liquid and gas Weber number, respectively. It is found that the disturbances occurred by the gas Weber number controls the instability process for the liquid sheet breakup. The results show that there is a range of gas Weber number for the occurrence of droplet. In this range, the gas Weber number causes an aerodynamic normal force at the tip of the liquid sheet which is able to form a droplet from the tip of the liquid sheet. Below that range of gas Weber number, the aerodynamic normal force at the tip of the sheet is too low to produce a droplet and above the range, the aerodynamic normal force stretches the liquid sheet too much and no droplet occurs.

scholarly journals Physics of Breakup in Liquid Column and Sheet

2011 ◽  
Vol 8 (2) ◽  
pp. 59
Author(s):  
M. Ali ◽  
M. Q. Islam ◽  
M. Khadem
Keyword(s):  
Surface Tension ◽  
Shear Force ◽  
Aerodynamic Force ◽  
Surface Tension Force ◽  
Liquid Sheet ◽  
Capillary Waves ◽  
Liquid Column ◽  
Capillary Instabilities ◽  
Sheet Breakup ◽  
Moving Liquid

 The details on breakup processes of liquid column and sheet are numerically investigated to provide the physics of the capillary instabilities and formation of liquid drops. Two cases are used: A numerical analysis on the capillary instabilities and breakup processes of a cylindrical liquid column and a moving liquid sheet in a moving gaseous medium to analyze the dynamics and breakup of the liquid sheet. The problem, composed of the Navier-Stokes systems associated with surface tension forces, is solved by the Volume of Fluid (VOF) technique with a Continuum Surface Force (CSF) to artificially smooth the discontinuity present at the interface. The results show that before disintegration of the liquid the capillary waves become unstable and the source of making the wave unstable is inherently developed by the system. The investigation of moving liquid sheet showed that the two modes of forces for liquid stretching exists: shear force causing the stretching of liquid by shear velocity and drag force causing the stretching of liquid by gas velocity ahead of the tip of the liquid sheets. Stretching of liquid by shear force causes the protrusion of liquid from the tip of liquid sheet and the surface tension force causes the tip of the sheet to make it round. It can also be revealed that the aerodynamic force at the tip of the sheet plays an important role to continue the stretching of sheet and controls the formation of droplet with the occurrence of sheet breakup. 

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.

DUAL-MODE LINEAR ANALYSIS OF TEMPORAL INSTABILITY FOR POWER-LAW LIQUID SHEET

2016 ◽  
Vol 26 (4) ◽  
pp. 319-347 ◽  
Author(s):  
Han-Yu Deng ◽  
Feng Feng ◽  
Xiao-Song Wu
Keyword(s):  
Power Law ◽  
Linear Analysis ◽  
Liquid Sheet ◽  
Dual Mode ◽  
Temporal Instability

ELECTROHYDRODYNAMIC INSTABILITY OF LIQUID SHEET SATURATING POROUS MEDIUM WITH INTERFACIAL SURFACE CHARGES

2013 ◽  
Vol 23 (2) ◽  
pp. 165-191
Author(s):  
Mohamed F. El-Sayed ◽  
M. H. M. Moussa ◽  
Ahmed A. A. Hassan ◽  
N. M. Hafez
Keyword(s):  
Porous Medium ◽  
Liquid Sheet ◽  
Surface Charges ◽  
Electrohydrodynamic Instability ◽  
Interfacial Surface

HOLOGRAPHY EXPERIMENTS IN THE BREAKUP REGION OF A LIQUID SHEET FORMED BY TWO IMPINGING JETS

1995 ◽  
Vol 5 (4-5) ◽  
pp. 387-402 ◽  
Author(s):  
B. S. Kang ◽  
Y. B. Shen ◽  
D. Poulikakos
Keyword(s):  
Impinging Jets ◽  
Liquid Sheet
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