Annular liquid sheets and its dynamics - A review

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.

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Instability of viscoelastic annular liquid sheets subjected to unrelaxed axial elastic tension

Journal of Non-Newtonian Fluid Mechanics ◽

10.1016/j.jnnfm.2013.04.002 ◽

2013 ◽

Vol 198 ◽

pp. 31-38 ◽

Cited By ~ 7

Author(s):

Li-Jun Yang ◽

Ming-Xi Tong ◽

Qing-Fei Fu

Keyword(s):

Liquid Sheets

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A Comprehensive Model to Predict Simplex Atomizer Performance

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/98-gt-441 ◽

1998 ◽

Cited By ~ 2

Author(s):

Y. Liao ◽

A. T. Sakman ◽

S. M. Jeng ◽

M. A. Jog ◽

M. Benjamin

Keyword(s):

Stability Analysis ◽

Film Thickness ◽

Linear Stability ◽

Linear Stability Analysis ◽

Liquid Fuel ◽

Density Ratio ◽

Liquid Sheet ◽

Unstable Wave ◽

Liquid Sheets ◽

Breakup Model

The performance of liquid fuel atomizer has direct effects on combustion efficiency, pollutant emission and stability. Pressure swirl atomizer, or simplex atomizer, is widely used in liquid fuel combustion devices in aircraft and power generation industry. A computational, experimental, and theoretical study is conducted to predict its performance. The Arbitrary-Lagrangian-Eulerian method with finite volume scheme is employed in the CFD model. Internal flow characteristics of the simplex atomizer as well as its performance parameters such as discharge coefficient, spray angle and film thickness are predicted. A temporal linear stability analysis is performed for cylindrical liquid sheets under 3-D disturbance. The model incorporates swirling velocity component, finite film thickness and radius which are essential features of conical liquid sheets emanating from simplex atomizers. It is observed that the relative velocity between liquid and gas phase, density ratio and surface curvature enhance the interfacial aerodynamic instability. As Weber number and density ratio increase, both the wave growth rate and the unstable wave number range increase. Combination of axial and swirling velocity components is more effective than single axial component for disintegration of liquid sheet. A breakup model for conical liquid sheet is proposed. Combining the breakup model with linear stability analysis, mean drop sizes are predicted. The theoretical results are compared with measurement data and agreement is very good.

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Surface Fluctuation Analysis for Turbulent Liquid Sheets

Fusion Science & Technology ◽

10.13182/fst04-a419 ◽

2004 ◽

Vol 45 (1) ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Samuel G. Durbin ◽

Timothy P. Koehler ◽

Jefferey J. R. Reperant ◽

Minami Yoda ◽

Said I. Abdel-Khalik ◽

...

Keyword(s):

Fluctuation Analysis ◽

Liquid Sheets ◽

Surface Fluctuation

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Atomization of acoustically forced liquid sheets

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.732 ◽

2019 ◽

Vol 880 ◽

pp. 653-683 ◽

Cited By ~ 1

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.

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