DETECTION OF AERODYNAMIC EFFECTS IN LIQUID JET BREAKUP AND DROPLET FORMATION

1999 ◽  
Vol 9 (4) ◽  
pp. 331-342 ◽  
Author(s):  
Michael P. Moses ◽  
Steven H. Collicott ◽  
Stephen D. Heister
Keyword(s):  
Droplet Formation ◽  
Liquid Jet ◽  
Jet Breakup

DROPLET FORMATION FROM A THIN HOLLOW LIQUID JET WITH A CORE AIR FLOW

2005 ◽  
Vol 15 (5) ◽  
pp. 469-488 ◽  
Author(s):  
Chul Jin Choi ◽  
Sang Yong Lee
Keyword(s):  
Air Flow ◽  
Droplet Formation ◽  
Liquid Jet

Simulation of Laminar Liquid Jets in Gaseous Crossflow Before the Onset of Primary Breakup

2011 ◽  
Author(s):  
C.-L. Ng ◽  
K. A. Sallam
Keyword(s):  
Experimental Data ◽  
Fuel Injection ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Jet Breakup ◽  
Primary Breakup ◽  
Density Ratios ◽  
First Time ◽  
Two Sides ◽  
Reduced Pressures

The deformation of laminar liquid jets in gaseous crossflow before the onset of primary breakup is studied motivated by its application to fuel injection in jet afterburners and agricultural sprays, among others. Three crossflow Weber numbers that represent three different liquid jet breakup regimes; column, bag, and shear breakup regimes, were studied at large liquid/gas density ratios and small Ohnesorge numbers. In each case the liquid jet was simulated from the jet exit and ended before the location where the experimental data indicated the onset of breakup. The results show that in column and bag breakup, the reduced pressures along the sides of the jet cause the liquid to move to the sides of the jet and enhance the jet deformation. In shear breakup, the flattened upwind surface pushes the liquid towards the two sides of the jet and causing the gaseous crossflow to separate near the edges of the liquid jet thus preventing further deformation before the onset of breakup. It was also found out that in shear breakup regime, the liquid phase velocity inside the liquid jet was large enough to cause onset of ligament formation along the jet side, which was not the case in the column and bag breakup regimes. In bag breakup, downwind surface waves were observed to grow along the sides of the liquid jet triggered a complimentary experimental study that confirmed the existence of those waves for the first time.

scholarly journals Stability of a Viscous Liquid Jet in a Coaxial Twisting Compressible Airflow

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 918
Author(s):  
Li-Mei Guo ◽  
Ming Lü ◽  
Zhi Ning
Keyword(s):  
Viscous Liquid ◽  
Axial Velocity ◽  
Liquid Velocity ◽  
Velocity Ratio ◽  
Dominant Mode ◽  
Liquid Jet ◽  
Axisymmetric Mode ◽  
Jet Instability ◽  
Jet Stability ◽  
Jet Breakup

Based on the linear stability analysis, a mathematical model for the stability of a viscous liquid jet in a coaxial twisting compressible airflow has been developed. It takes into account the twist and compressibility of the surrounding airflow, the viscosity of the liquid jet, and the cavitation bubbles within the liquid jet. Then, the effects of aerodynamics caused by the gas–liquid velocity difference on the jet stability are analyzed. The results show that under the airflow ejecting effect, the jet instability decreases first and then increases with the increase of the airflow axial velocity. When the gas–liquid velocity ratio A = 1, the jet is the most stable. When the gas–liquid velocity ratio A > 2, this is meaningful for the jet breakup compared with A = 0 (no air axial velocity). When the surrounding airflow swirls, the airflow rotation strength E will change the jet dominant mode. E has a stabilizing effect on the liquid jet under the axisymmetric mode, while E is conducive to jet instability under the asymmetry mode. The maximum disturbance growth rate of the liquid jet also decreases first and then increases with the increase of E. The liquid jet is the most stable when E = 0.65, and the jet starts to become more easier to breakup when E = 0.8425 compared with E = 0 (no swirling air). When the surrounding airflow twists (air moves in both axial and circumferential directions), given the axial velocity to change the circumferential velocity of the surrounding airflow, it is not conducive to the jet breakup, regardless of the axisymmetric disturbance or asymmetry disturbance.

Jet Breakup and Droplet Formation in Immiscible Liquid-Liquid System

2016 ◽  
Author(s):  
Shimpei Saito ◽  
Yuzuru Iwasawa ◽  
Yutaka Abe ◽  
Akiko Kaneko ◽  
Tetsuya Kanagawa ◽  
...  
Keyword(s):  
Weber Number ◽  
Droplet Diameter ◽  
Droplet Formation ◽  
Liquid System ◽  
Immiscible Liquid ◽  
Satellite Droplet ◽  
Breakup Length ◽  
Jet Breakup ◽  
Fundamental Process ◽  
Median Diameter

Mitigative measures against the event of a core disruptive accident (CDA) are of the importance from the viewpoint of safety of a sodium-cooled fast reactor (SFR). If the CDA occurs, the so-called post-accident heat removal must be surely achieved. The present study focuses on the scenario that the molten materials are injected into the lower plenum as jets. The jet breakup behavior during the CDA will be very complicated. Therefore, a specialized study on the fundamental process during the jet breakup is believed to be an effective approach. The aim of this paper is to understand the fundamental process of hydrodynamic interaction of jet breakup and droplet formation Using the immiscible liquid-liquid system, water and silicon oil as the test fluids, visualization via high-speed videography was performed. From the visualization results, the breakup length and droplet diameter were measured by image processing. The experimental data were scaled with ambient Weber number. When the Weber number was smaller than 1, the droplet diameter was close to the nozzle diameter, and distribution of droplet size was not observed. When the Weber number exceeded 1, the breakup length became longer and the generated droplet diameter possessed a distribution with two peaks due to satellite droplet formation. In both cases, the droplet formed at the leading edge of jet. In case that Weber number is around 100, the droplets were formed by entrainment of interfacial wave at jet side. From the mass median diameter data, we can see that the increase of the Weber number caused the decrease of median diameter and the increase of the width of the distribution.

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.

scholarly journals Breakup Processes and Droplet Characteristics of Liquid Jets Injected into Low-Speed Air Crossflow

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 676
Author(s):  
Lingzhen Kong ◽  
Tian Lan ◽  
Jiaqing Chen ◽  
Kuisheng Wang ◽  
Huan Sun
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Weber Number ◽  
Droplet Size Distribution ◽  
Droplet Velocity ◽  
Liquid Jet ◽  
Outlet Section ◽  
Low Speed ◽  
Jet Breakup ◽  
Breakup Mode

The breakup processes and droplet characteristics of a liquid jet injected into a low-speed air crossflow in the finite space were experimentally investigated. The liquid jet breakup processes were recorded by high-speed photography, and phase-Doppler anemometry (PDA) was employed to measure the droplet sizes and droplet velocities. Through the instantaneous image observation, the liquid jet breakup mode could be divided into bump breakup, arcade breakup and bag breakup modes, and the experimental regime map of primary breakup processes was summarized. The transition boundaries between different breakup modes were found. The gas Weber number (Weg) could be considered as the most sensitive dimensionless parameter for the breakup mode. There was a Weg transition point, and droplet size distribution was able to change from the oblique-I-type to the C-type with an increase in Weg. The liquid jet Weber number (Wej) had little effect on droplet size distribution, and droplet size was in the range of 50–150 μm. If Weg > 7.55, the atomization efficiency would be very considerable. Droplet velocity increased significantly with an increase in Weg of the air crossflow, but the change in droplet velocity was not obvious with the increase in Wej. Weg had a decisive effect on the droplet velocity distribution in the outlet section of test tube.

Liquid jet breakup: A new method for the preparation of poly lactic-co-glycolic acid microspheres

2019 ◽  
Vol 137 ◽  
pp. 140-147 ◽  
Author(s):  
Yulong Xia ◽  
Meng Yuan ◽  
Mo Chen ◽  
Jin Li ◽  
Tianyuan Ci ◽  
...  
Keyword(s):  
Glycolic Acid ◽  
New Method ◽  
Liquid Jet ◽  
Jet Breakup

Experimental Investigation of Liquid Jet Breakup in a Cross Flow of a Swirling Air Stream

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari ◽  
Saadat Syed ◽  
Jeffery A. Lovett
Keyword(s):  
Experimental Investigation ◽  
Momentum Flux ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Penetration Behavior

This paper presents the results of an experimental investigation of liquid jet breakup in a cross flow of air under the influence of swirl (swirl numbers 0 and 0.2) at a fixed air flow Mach number 0.12 (typical gas turbine conditions). The experiments have been conducted for various liquid to air momentum flux ratios (q) in the range of 1 to 25. High speed (@ 500 fps) images of the jet breakup process are captured and those images are processed using matlab to obtain the variation of breakup length and penetration height with momentum flux ratio. Using the high speed images, an attempt has been made to understand the physics of the jet breakup process by identification of breakup modes—bag breakup, column breakup, shear breakup, and surface breakup. The results show unique breakup and penetration behavior which departs from the continuous correlations typically used. Furthermore, the images show a substantial spatial fluctuation of the emerging jet resulting in a wavy nature related to effects of instability waves. The results with 15 deg swirl show reduced breakup length and penetration related to the nonuniform distribution of velocity that offers enhanced fuel atomization in swirling fuel nozzles.

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