Parametric Study of Primary Breakup of Turbulent Liquid Jets in Crossflow: Role of Weber number

2010 ◽  
Author(s):  
Madhusudan Pai ◽  
Ivan Bermejo-Moreno ◽  
Olivier Desjardins ◽  
Heinz Pitsch
Keyword(s):  
Parametric Study ◽  
Weber Number ◽  
Liquid Jets ◽  
Primary Breakup

On the Breakup Process of Round Liquid Jets in Gaseous Crossflows at Low Weber Number

2013 ◽  
Author(s):  
Shao-lin Wang ◽  
Yong Huang ◽  
Fang Wang ◽  
Zhi-lin Liu ◽  
Lei Liu
Keyword(s):  
Weber Number ◽  
High Speed ◽  
Droplet Diameter ◽  
Liquid Jets ◽  
Breakup Process ◽  
Ohnesorge Number ◽  
Propulsion Systems ◽  
Momentum Ratio ◽  
Breakup Length ◽  
Primary Breakup

Liquid jets in cross air flows are widely used and play an important role in propulsion systems, such as ramjet combustors. In this paper, experiments were carried out to investigate the properties of the primary breakup of liquid jets in subsonic transverse airflows at low Weber number. The test ranges included crossflow Weber numbers of 0.5–6.7, liquid-to-gas momentum ratios of 3–120, and Ohnesorge number of 0.0086. Four different injectors with diameter 0.4mm, 0.5mm, 0.6mm and 1mm have been used. A high speed camera was used to observe the jet column breakup process. Results show that the surface wavelength decreases not only with the increase of the gas Weber number but also with the increase of the momentum ratio. The breakup length decreases with the increase of the gas Weber number, in addition to its increase with the increase of the momentum ratio. The droplet diameter decreases with the increase of both the gas Weber number and momentum ratio, although the gas Weber number will dominate the breakup process. The surface wavelength, breakup length, and droplet diameter were also analyzed with to obtain semi-theoretical correlations.

PRIMARY BREAKUP OF ROUND AERATED-LIQUID JETS IN SUPERSONIC CROSSFLOWS

2006 ◽  
Vol 16 (6) ◽  
pp. 657-672 ◽  
Author(s):  
K. A. Sallam ◽  
C. Aalburg ◽  
G. M. Faeth ◽  
K.-C. Lin ◽  
C. D. Carter ◽  
...  
Keyword(s):  
Liquid Jets ◽  
Primary Breakup

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 Breakup of the Water Sheet Formed by Two Liquid Impinging Jets

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Yakang Xia ◽  
Lyes Khezzar ◽  
Shrinivas Bojanampati ◽  
Arman Molki
Keyword(s):  
Weber Number ◽  
Reynolds Numbers ◽  
Impinging Jets ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Impingement Angle ◽  
Number Range ◽  
Breakup Length ◽  
Sheet Breakup ◽  
Visualization Experiments

Flow visualization experiments are carried out to study the flow regimes and breakup length of the water sheet generated by two impinging liquid jets from an atomizer made of two identical tubes 0.686 mm in diameter. These experiments cover liquid jet Reynolds numbers based on the pipe diameter in the range of 1541 to 5394. The effects of the jet velocities and impingement angle between the two jets on the breakup performance are studied. Four spray patterns are recognized, which are presheet formation, smooth sheet, ruffled sheet, and open-rim sheet regimes. Water sheet breakup length is found to be consistent with previous experimental and theoretical results in the lower Weber number (based on water jet diameter and velocity) range. In the relatively high Weber number range, the breakup length tends to a constant value with increasing Weber number, and some discrepancies between experimental and theoretical predictions do exist. Measured water sheet area increases with increasing liquid jet Reynolds numbers and impingement angle within the range of the current study.

Comparative study on interfacial oscillations of rectangular and elliptical liquid jets

2020 ◽  
Vol 234 (7) ◽  
pp. 1272-1286 ◽  
Author(s):  
Amin Jaberi ◽  
Mehran Tadjfar
Keyword(s):  
Aspect Ratio ◽  
Weber Number ◽  
High Speed ◽  
Nozzle Geometry ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Aspect Ratios ◽  
Water Jets ◽  
Switching Phenomenon ◽  
Axis Switching

The instability characteristics and flow structures of water jets injected from rectangular and elliptical nozzles with aspect ratios varying from 2 to 6 were experimentally studied and compared. Shadowgraph technique was employed for flow visualization, and structures on the liquid jet surface were captured using high speed photography. It was found that disturbances originating from the nozzle geometry initially perturbed the liquid column, and then, at high jet velocities, disturbances generated within the flow dominated the jet surface. It was also found that rectangular nozzles introduced more disturbances into the flow than the elliptical ones. The characteristic parameters of axis-switching phenomenon including wavelength, frequency, and amplitude were measured and compared. Axis-switching wavelength was found to increase linearly with Weber number. Also, the wavelengths of rectangular jets were longer than the elliptical jets. Further, the frequency of axis-switching was shown to be reduced with increase of both Weber number and aspect ratio. It was observed that the axis-switching amplitude increased monotonically, reached a peak, and then decreased gradually. It was also found that the axis-switching amplitude varied with Weber number. At lower values of Weber number, the rectangular nozzles had higher amplitude than the elliptical nozzles. However, at higher values of Weber number, this relation was reversed, and the elliptical nozzles had the higher axis-switching amplitudes. This reversal Weber number decreased with the orifice aspect ratio. The reversal Weber number for aspect ratio of 4 was about 289, and it had decreased to 144 for the aspect ratio of 6.

scholarly journals Effects of Nanoparticle Additives on Spray Characteristics of Liquid Jets in Gaseous Crossflow

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1574
Author(s):  
Weidong Shi ◽  
Fengyu Li ◽  
Qizhao Lin ◽  
Guofeng Fang ◽  
Liang Chen ◽  
...  
Keyword(s):  
High Performance ◽  
Liquid Jets ◽  
Pure Liquid ◽  
Fracture Position ◽  
Transition Mechanism ◽  
Basic Fluid ◽  
Jet Trajectory ◽  
Primary Breakup ◽  
Transverse Injection ◽  
Nanoparticle Additives

Nanofluids are attracting attention as future energy carriers owing to their high performance for improving combustion and heat transfer. In this study, the macroscopic characteristics of nanofluid jets in a subsonic gaseous crossflow were investigated by focusing on the influence of nanoparticle additives on the breakup process. Based on a distribution map of the image grayscale standard deviation, we propose an improved method to process transverse injection shadowgraphs. A simplified model of the transition mechanism from column breakup to surface breakup at a small Weber number was established. The effects of nanoparticles on the jet trajectory and column fracture position were analyzed according to the deviations from the pure liquid. To interpret the effects of the nanoparticles, a new nondimensional parameter was introduced into the empirical correlation of the column fracture position. The results indicated that at low concentrations of nanoparticles, the surface tension of the nanofluids increased slightly, while the viscosity increased significantly (by up to 23%). These changes in the physical properties had little effect on the breakup regimes or jet trajectory. Moreover, the nanoparticles promoted cavitation inside the liquid column, resulting in an additional primary breakup mode for the nanofluids. Consequently, the length of the column fracture was reduced by up to 20% compared with that of the basic fluid.

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