Theoretical Analysis of Surface Waves on Liquid Jets in Crossflows with Deformation

2013 ◽  
Vol 681 ◽  
pp. 152-157
Author(s):  
Shao Lin Wang ◽  
Yong Huang ◽  
Fang Wang ◽  
Zhi Lin Liu
Keyword(s):  
Growth Rate ◽  
Theoretical Analysis ◽  
Surface Waves ◽  
Cross Section ◽  
Aerodynamic Force ◽  
Linear Instability ◽  
Wave Number ◽  
Liquid Jets ◽  
Liquid Jet ◽  
The Cross

Liquid jets in cross air flows are widely used and play an important role in propulsion systems, such as ramjet combustors. Surface waves on the liquid jets in gaseous crossflows have been observed in numerous experiments. Especially for lower gas Webber number, liquid jets breaks up due to the surface waves. However compared with injecting into gas coaxial flow, liquid jet will be deformed in crossflow due to the transverse aerodynamic force. Deformation of jet is investigated by analyzing stress force equilibrium of the cross-section. Though linear instability analysis, dispersion relation and growth rate of surface waves of liquid jet with deformation were derived. According to the present theoretical analysis, the cross-section shape can be deformed to stable ellipse only if the gas velocity was lower than 9m/s for 1mm diameter jet. The maximum growth rate of disturbances takes place at wave number 0.7 approximately, and it will decrease with increasing the jet diameter. The range of instable wave number will expand and the most instable wave number will grow for the deformed jets.

Linear Instability Analysis of an Annular Swirling Viscous Liquid Jet

2011 ◽  
Vol 66-68 ◽  
pp. 1556-1561 ◽  
Author(s):  
Kai Yan ◽  
Ming Lv ◽  
Zhi Ning ◽  
Yun Chao Song
Keyword(s):  
Viscous Liquid ◽  
Liquid Velocity ◽  
Aerodynamic Force ◽  
Numerical Procedure ◽  
Liquid Sheet ◽  
Linear Instability ◽  
Viscous Force ◽  
Liquid Jet ◽  
Instability Analysis ◽  
Linear Instability Analysis

A three-dimensional linear instability analysis was carried out for an annular swirling viscous liquid jet with solid vortex swirl velocity profile. An analytical form of dispersion relation was derived and then solved by a direct numerical procedure. A parametric study was performed to explore the instability mechanisms that affect the maximum spatial growth rate. It is observed that the liquid swirl enhances the breakup of liquid sheet. The surface tension stabilizes the jet in the low velocity regime. The aerodynamic force intensifies the developing of disturbance and makes the jet unstable. Liquid viscous force holds back the growing of disturbance and the makes the jet stable, especially in high liquid velocity regime.

scholarly journals Effects of Asymmetric Gas Distribution on the Instability of a Plane Power-Law Liquid Jet

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1854 ◽  
Author(s):  
Jin-Peng Guo ◽  
Yi-Bo Wang ◽  
Fu-Qiang Bai ◽  
Fan Zhang ◽  
Qing Du
Keyword(s):  
Power Law ◽  
Liquid Velocity ◽  
Linear Instability ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Critical Curves ◽  
Jet Breakup ◽  
Plane Jets ◽  
Gas Space ◽  
Aerodynamic Asymmetry

As a kind of non-Newtonian fluid with special rheological features, the study of the breakup of power-law liquid jets has drawn more interest due to its extensive engineering applications. This paper investigated the effect of gas media confinement and asymmetry on the instability of power-law plane jets by linear instability analysis. The gas asymmetric conditions mainly result from unequal gas media thickness and aerodynamic forces on both sides of a liquid jet. The results show a limited gas space will strengthen the interaction between gas and liquid and destabilize the power-law liquid jet. Power-law fluid is easier to disintegrate into droplets in asymmetric gas medium than that in the symmetric case. The aerodynamic asymmetry destabilizes para-sinuous mode, whereas stabilizes para-varicose mode. For a large Weber number, the aerodynamic asymmetry plays a more significant role on jet instability compared with boundary asymmetry. The para-sinuous mode is always responsible for the jet breakup in the asymmetric gas media. With a larger gas density or higher liquid velocity, the aerodynamic asymmetry could dramatically promote liquid disintegration. Finally, the influence of two asymmetry distributions on the unstable range was analyzed and the critical curves were obtained to distinguish unstable regimes and stable regimes.

Experimental Characterization of Intrinsic Properties Associated With Air-Assisted Liquid Jet and Liquid Sheet

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
K. Balaji ◽  
V. Sivadas ◽  
Vishnu Radhakrishna ◽  
Khushal Ashok Bhatija ◽  
K. Sai Charan
Keyword(s):  
High Speed ◽  
Liquid Sheet ◽  
Interfacial Instability ◽  
Wave Number ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Experimental Characterization ◽  
Interfacial Wave ◽  
Visualization Techniques

The present study focuses on experimental characterization of interfacial instability pertinent to liquid jet and liquid sheet in the first wind-induced zone. To accomplish this objective, the interfacial wave growth rate, critical wave number, and breakup frequency associated with air-assisted atomizer systems were extracted by utilizing high-speed flow visualization techniques. For a range of liquid to gas velocities tested, nondimensionalization with appropriate variables generates the corresponding correlation functions. These functions enable to make an effective comparison between interfacial wave developments for liquid jet and sheet configurations. It exhibits liquid sheets superiority over liquid jets in the breakup processes leading to efficient atomization.

Curved Non-Newtonian Liquid Jets With Surfactants

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Jamal Uddin ◽  
Stephen P. Decent
Keyword(s):  
Free Surface ◽  
Shear Thickening ◽  
Linear Instability ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Long Wavelength ◽  
Droplet Sizes ◽  
Wavelength Approximation ◽  
Steady Solutions ◽  
Linear Instability Analysis

Applications of the breakup of a liquid jet into droplets are common in a variety of different industrial and engineering processes. One such process is industrial prilling, where small spherical pellets and beads are generated from the rupture of a liquid thread. In such a process, curved liquid jets produced by rotating a perforated cylindrical drum are utilized to control drop sizes and breakup lengths. In general, smaller droplets are observed as the rotation rate is increased. The addition of surfactants along the free surface of the liquid jet as it emerges from the orifice provides a possibility of further manipulating breakup lengths and droplet sizes. In this paper, we build on the work of Uddin et al. (2006, “The Instability of Shear Thinning and Shear Thickening Liquid Jets: Linear Theory,” ASME J. Fluids Eng., 128, pp. 968–975) and investigate the instability of a rotating liquid jet (having a power law rheology) with a layer of surfactants along its free surface. Using a long wavelength approximation we reduce the governing equations into a set of one-dimensional equations. We use an asymptotic theory to find steady solutions and then carry out a linear instability analysis on these solutions.

The Determinants of Idiosyncratic Volatility

2017 ◽  
Vol 25 (4) ◽  
pp. 509-545
Author(s):  
Jaeuk Khil ◽  
Song Hee Kim ◽  
Eun Jung Lee
Keyword(s):  
Growth Rate ◽  
Time Series ◽  
Cross Section ◽  
Growth Rates ◽  
Idiosyncratic Volatility ◽  
Return Volatility ◽  
Firm Level ◽  
Cross Sectional ◽  
Asset Growth ◽  
The Cross

We investigate the cross-sectional and time-series determinants of idiosyncratic volatility in the Korean market. In particular, we focus on the empirical relation between firms’ asset growth rate and idiosyncratic stock return volatility. We find that, in the cross-section, companies with high idiosyncratic volatility tend to be small and highly leveraged, have high variance of ROE and Market to Book ratio, high turnover rate, and pay no dividends. Furthermore, firms with extreme (either high positive or negative) asset growth rates have high idiosyncratic return volatility than firms with moderate growth rates, suggesting the V-shaped relation between asset growth rate and idiosyncratic return volatility. We find that the V-shaped relation is robust even after controlling for other factors. In time-series, we find that firm-level idiosyncratic volatility is positively related to the dispersion of the cross-sectional asset growth rates. As a result, this study is contributed to show that the asset growth is the most important predictor of firm-level idiosyncratic return volatility in both the cross-section and the time-series in the Korean stock market. In addition, we show how the effect of risk factors varies with industries.

THEORETICAL ANALYSIS OF SURFACE WAVES ON A ROUND LIQUID JET IN A GASEOUS CROSSFLOW

2014 ◽  
Vol 24 (1) ◽  
pp. 23-40 ◽  
Author(s):  
Shaolin Wang ◽  
Y. Huang ◽  
Z. L. Liu
Keyword(s):  
Theoretical Analysis ◽  
Surface Waves ◽  
Liquid Jet

Linear Instability Analysis of an Annular Liquid Sheet With Inner and Outer Gas Flow

2009 ◽  
Author(s):  
Fathollah Ommi ◽  
Seid Askari Mahdavi ◽  
S. Mostafa Hosseinalipour ◽  
Ehsan Movahednejad
Keyword(s):  
Growth Rate ◽  
Dispersion Equation ◽  
Liquid Sheet ◽  
Linear Instability ◽  
Wave Number ◽  
Unstable Wave ◽  
Instability Analysis ◽  
Air Stream ◽  
Linear Instability Analysis ◽  
Air Streams

A linear instability analysis of an inviscid annular liquid sheet emanating from an atomizer subjected to inner and outer swirling air streams has been carried out. The dimensionless dispersion equation that governs the instability is derived. The dispersion equation solved by Numerical method to investigate the effects of the liquid-gas swirl orientation on the maximum growth rate and its corresponding unstable wave number that it produces the finest droplets. To understand the effect of air swirl orientation with respect to liquid swirl direction, four possible combinations with both swirling air streams with respect to the liquid swirl direction have been considered. Results show that at low liquid swirl Weber number a combination of co-inner air stream and counter-outer air stream has the largest most unstable wave number and shortest breakup length. The combination of inner and the outer air stream co-rotating with the liquid has the highest growth rate.

Deformation and Surface Waves Properties of Round Nonturbulent Liquid Jets in Gaseous Crossflow

2005 ◽  
Author(s):  
C.-L. Ng ◽  
K. A. Sallam ◽  
H. M. Metwally ◽  
C. Aalburg
Keyword(s):  
Surface Waves ◽  
Weber Number ◽  
Computational Study ◽  
Density Ratio ◽  
Three Dimensional ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Liquid Viscosity ◽  
Fluent Software ◽  
Wave Properties

A computational study of the deformation and surface wave properties of nonturbulent round liquid jets in gaseous crossflow is described. The objective of the study was to consider effects of liquid viscosity, liquid/gas density ratio, and crossflow Weber number that are representative of practical sprays. Three-dimensional computations of the deformation of round liquid jets in gaseous crossflow were carried out using FLUENT software utilizing its Volume of Fluid (VOF) module. The computations were evaluated satisfactorily based on earlier measurements of the properties of nonturbulent round liquid jets in crossflow (liquid jet deformation and surface waves) and revealed three-dimensional properties of the surface waves that could not be observed by previous measurements that were taken from the side of the jet.

Capillary Instability of Liquid Jets Issuing From Elliptic Nozzles

2010 ◽  
Author(s):  
Ghobad Amini ◽  
Ali Dolatabadi
Keyword(s):  
Surface Tension ◽  
Growth Rate ◽  
Aspect Ratio ◽  
Stokes Equations ◽  
Practical Importance ◽  
Nozzle Geometry ◽  
Navier Stokes ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Breakup Mechanism

Breakup of a liquid jet issuing from an orifice is one of the classical problems in fluid dynamics due to its theoretical and practical importance. The main application of the process is in spray and droplet formation, which is of interest in the combustion in liquid-fuelled engines, ink-jet printers, coating systems, medical equipment, and irrigation device. The complexity of the breakup mechanism is due to the large number of parameters involved such as the design of injection nozzle, and thermodynamic states of both liquid and gas. In addition, different combinations of surface tension, inertia, and aerodynamic forces acting on the jet, define main breakup regimes. Effects of nozzle geometry on the behavior of liquid jets have been overlooked in the literature. Elliptic jets have never been investigated theoretically since mostly circular jets or liquid sheets have been analyzed; while experiments have shown that by using elliptical nozzles, entrainment and air mixing of fuel in combustion will be increased. In this article, instability of an elliptic liquid jet under the effect of inertia, viscous, and surface tension forces has been studied using temporal linear analyses. The effects of the gravity and the surrounding gas have been neglected. 1-D Cosserat equation (directed curve) has been used which can be considered as simplified form of Navier-Stokes equations. Results are comparable with classical Rayleigh mode of circular jet when the aspect ratio (ratio of major to minor axis) is one. Growth rate of instability on an elliptic liquid jet under various conditions has been compared with those of a circular jet. Results show that in comparison with a circular jet, the elliptic jet is more unstable and by increasing the aspect ratio the instability grows faster. In addition, similar to the circular case, the effect of viscosity is diminishing the growth rate for the elliptic jet.

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