Condensation on Coherent Turbulent Liquid Jets: Part I—Experimental Study

1989 ◽  
Vol 111 (4) ◽  
pp. 1068-1074 ◽  
Author(s):  
S. Kim ◽  
A. F. Mills
Keyword(s):  
Surface Tension ◽  
High Speed ◽  
Reynolds Numbers ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Turbulence Level ◽  
Jet Breakup ◽  
Glass Tubes ◽  
Initial Turbulence ◽  
Jet Velocities

Condensation on coherent turbulent liquid jets was investigated experimentally in order to obtain a data base for the liquid side heat transfer coefficient. Jet breakup was identified by means of high-speed photography. Nozzles were formed from smooth and roughened glass tubes to define the initial turbulence level in the jets. Jet diameters of 3–7 mm and lengths of 2–12 cm were tested at jet velocities of 1.4–12 m/s giving Reynolds numbers of 6000–40,000. Viscosity and surface tension were varied by using ethanol, and water from 277–300 K, as test liquids. The Stanton number was found to be essentially independent of jet diameter, but to decrease with length to the power of −0.57, velocity to the power of −0.20, surface tension to the power of −0.30, and viscosity to the power of −0.1.

Simulation of jet velocity in the melt-blowing process using the coupled air–polymer model

2018 ◽  
Vol 89 (16) ◽  
pp. 3221-3233 ◽  
Author(s):  
Xibo Hao ◽  
Hui Huang ◽  
Yongchun Zeng
Keyword(s):  
High Speed ◽  
Flow Model ◽  
Processing Parameters ◽  
High Speed Photography ◽  
Critical Factors ◽  
Polymer Model ◽  
Melt Blowing ◽  
Two Phase ◽  
Jet Velocity ◽  
Jet Velocities

The polymer jet velocity is one of the most basic and critical factors in the melt-blowing process and has always been difficult to measure online. Much effort has been made on the numerical prediction of the jet velocity. However, little work has involved the complex interaction between the air flow and the polymer. Here, the Level-Set method is used to develop the coupled air–polymer two-phase flow model, and to simulate the polymer jet motion in the melt-blowing process considering the coupled effect of the air and polymer. Meanwhile, high-speed photography is adopted in the experiments to verify the simulation results. The x- and y-components of the jet velocities and the whipping amplitude of the jet motion are discussed. The rapid increase of jet velocity and the decrease of jet diameter show that most attenuation of the polymer jet occurred within a distance close to the die (10 mm). Based on the model, the effects of the processing parameters on the jet velocity are examined numerically.

High-Speed Photography of Liquid Jets

1975 ◽  
pp. 442-447 ◽  
Author(s):  
D. A. Gorham ◽  
J. E. Field
Keyword(s):  
High Speed ◽  
Liquid Jets ◽  
High Speed Photography

Hydraulic Performance and Jet Breakup Characteristics of the Impact Sprinkler with Circular and Non-circular Nozzles

2019 ◽  
Vol 35 (6) ◽  
pp. 911-924 ◽  
Author(s):  
Yue Jiang ◽  
Hong Li ◽  
Chao Chen ◽  
Lin Hua ◽  
Daming Zhang
Keyword(s):  
High Speed ◽  
Cone Angle ◽  
Hydraulic Performance ◽  
High Speed Photography ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Circular Jets ◽  
Square Jets ◽  
The Impact

HighlightsThe hydraulic performance of the impact sprinkler with circular and non-circular nozzles were measured.A High-Speed Photography (HSP) technique was employed to extract the jet breakup process of the impact sprinkler.Two index equations of jet characteristic lengths and equivalent diameters of non-circular nozzles were fitted. Abstract. An experiment was carried out to investigate the hydraulic performance of an impact sprinkler by using circular and non-circular nozzles. A High-Speed Photography (HSP) technique was employed to extract the breakup process and flow behavior of low-intermediate pressure water jets issued from the different types of orifices. These orifices were selected by the principle of equal flowrate with the same pressure. Moreover, two characteristic lengths: the jet breakup length and the initial amplitude of surface wave were measured. It was found that the sprinkler with circular nozzles produced the largest radius of throw followed by square nozzles and regular triangular nozzles when the cone angle of nozzle and pressure were unchanged, while the sprinkler with regular triangular nozzle had the best variation trend of water distribution and combination uniformity coefficient. Regular triangular jets exhibited a higher degree in breakup and the shortest breakup length compared with the square jets and the circular jets. The initial amplitudes of surface waves of regular triangular jets were larger than the square jets and the circular jets with the same cone angle. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular orifices were fitted with a relative error of less than 10%, which means the fitting formulas were accurate. Keywords: Breakup length, Fitting formula, Hydraulic performance, Initial amplitude, Non-circular jets.

Flow Characteristics of Rectangular Liquid Jets Injected Into Low Subsonic Crossflow

2019 ◽  
Author(s):  
M. Tadjfar ◽  
A. Jaberi ◽  
R. Shokri
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Combustion Efficiency ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Aspect Ratios ◽  
Jet Trajectory ◽  
Wide Range ◽  
Circular Holes ◽  
Subsonic Crossflow

Abstract Perpendicular injection of liquid jets into gaseous crossflow is well-known as an effective way to obtain good mixing between liquid fuel and air crossflow. Mostly, injectors with circular holes were used as the standard method of fuel spraying. However, recently a great attention to injectors with non-circular holes has emerged that aims to improve the quality of fuel mixing and consequently combustion efficiency. In the present work, rectangular injectors with different aspect ratios varying from 1 to 4 were experimentally studied. Using a wind tunnel with maximum air velocity of 42 m/s, tests were performed for a wide range of flow conditions including liquid-to-air momentum ratios of 10, 20, 30 and 40. Backlight shadowgraphy and high speed photography were employed to capture the instantaneous physics of the liquid jets discharged into gaseous crossflow. The flow physics of the rectangular liquid jets were investigated by means of flow visualizations. Different regimes of flow breakup including capillary, arcade, bag and multimode were observed for rectangular jets. Moreover, a new technique was used to calculate the trajectory of the liquid jets. It was shown the nozzle’s shape has no significant effect on jet trajectory. Also, the momentum ratio was found to has a profound effect on jet trajectory.

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.

Experimental Investigation on Flow and Breakup of Two-Dimensional Liquid Jets

2019 ◽  
Author(s):  
Amin Jaberi ◽  
Mehran Tadjfar
Keyword(s):  
High Speed ◽  
Volume Flow Rate ◽  
Quantitative Description ◽  
Sheet Thickness ◽  
Liquid Jets ◽  
Liquid Jet ◽  
High Speed Photography ◽  
Two Dimensional ◽  
Aspect Ratios ◽  
Wide Range

Abstract Studying of injectors with non-circular geometries has recently come to the spotlight of researchers as a potential technique to improve the liquid injection characteristics of different systems. In this work, the flow physics and breakup of two-dimensional liquid jets issued from flat slits into still air were experimentally investigated. Three injectors with aspect ratios of 30, 60 and 90 and thickness of 0.35 mm were manufactured to obtain two-dimensional liquid flow at the nozzle exit. The tests were performed for a wide range of volume flow rate, varying from 10 L/h to 240 L/h. Backlight shadowgraphy and high speed photography were employed to capture the flow dynamics of the jets. In order to capture every detail of the flow, photos of the liquid jet were taken from two views with 90° from each other. Using the visualizations, different regimes of the jet flow were explored and a regime map was proposed to distinguish these regimes based on the non-dimensional parameters of the liquid jet. Moreover, quantitative description of the main features of jet flows were obtained using an in-house image processing program. Measurements of different parameters including convergence length, maximum width, breakup length, sheet thickness to name a few, were conducted.

Experimental Study on Jet Breakup Morphologies and Jet Characteristic Parameters of Non-circular Nozzles under Low-intermediate Pressures

2019 ◽  
Vol 35 (4) ◽  
pp. 617-632
Author(s):  
Yue Jiang ◽  
Hong Li ◽  
Lin Hua ◽  
Daming Zhang ◽  
Zakaria Issaka
Keyword(s):  
Surface Wave ◽  
High Speed ◽  
Flow Behavior ◽  
Initial Section ◽  
Droplet Formation ◽  
High Speed Photography ◽  
Breakup Length ◽  
Jet Breakup ◽  
Circular Jets ◽  
Pressure Water

Abstract. A High-Speed Photography (HSP) technique was used to investigate the breakup process and flow behavior of low-intermediate pressure water jets issued from square and triangular shaped nozzles. The non-circular orifices were designed based on the principle of equal flowrate with the same pressure in relation to the circular orifice. The breakup morphologies and boundary structures of the jets were studied under different nozzles and working pressures. Two forms of droplet formation and the process of droplet formation, in addition to the jet breakup lengths, initial amplitudes of surface waves and jet diffusion angles of different nozzles were evaluated. It was found that the jet presented a good continuity and fluidity in the initial section, and the fluid bands gradually appeared due to the air resistance and the jet break up as the disturbance intensifies. The degree of jet breakup was enhanced with the increase of pressure and cone nozzle angle. The random appearance of the fluid band structures and the dactylitic textures near the nozzles for non-circular jets appeared earlier than those produced by the circular jets. The small satellite droplets with different shapes and sizes were seen inside and outside the jet interface. Triangular jets exhibited the shortest breakup length, the initial amplitude of surface wave, and the diffusion angle of the jet at the same pressure were largest compared with square and circular jets. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular nozzles were fitted with a relative error of less than 10%, which means the fitting formulas are accurate. Keywords: Breakup length, High-speed photography, MATLAB simulation, Non-circular nozzle, Surface wave amplitude.

Influence of Jet Velocity on Jet Breakup in Immiscible Liquid-Liquid Systems

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Chi M Phan ◽  
Geoffrey M Evans
Keyword(s):  
Droplet Size ◽  
High Speed ◽  
Immiscible Liquid ◽  
Linear Instability ◽  
Liquid Jets ◽  
Instability Analysis ◽  
Jet Breakup ◽  
Liquid Systems ◽  
Jet Velocity ◽  
Simplified Solution

The breakup of a laminar liquid jet is the underling phenomena used to generate emulsions in micro-scale devices. Jet breakup is induced by the most unstable disturbance growing on the jet surface, and linear instability analysis can be utilized to predict the resultant droplet size. Previously, instability analysis has been applied to stationary jets at intermediate Re only. This study investigates the influence of the jet velocity on the jet breakup at low Re number. The breakups of moving liquid jets were monitored using a high speed camera. The jet diameter, jet breakup length and resultant droplet sizes were strongly influenced by jet velocity. In addition to a simplified solution, a linear analysis for a moving jet was developed to determine the resultant droplet size. It was found that the full analysis is required to correctly predict the droplet size at low Re number.

Flow Development of a Liquid Sheet Issued Into Low-Speed Airstream

2020 ◽  
Author(s):  
Amin Jaberi ◽  
Mehran Tadjfar
Keyword(s):  
High Speed ◽  
Liquid Sheet ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Low Speed ◽  
Liquid Sheets ◽  
Flow Development ◽  
Flow Feature ◽  
Subsonic Crossflow ◽  
Jet Characteristics

Abstract In this study, a liquid sheet with an aspect ratio of 90 and a thickness of 0.35 was experimentally investigated when issued into a low-speed subsonic crossflow. High speed photography and shadowgraphy technique were employed to capture the instantaneous physics of the liquid sheet. Flow visualizations were used to investigate the flow development of the liquid sheet. It was found that this flow exhibited a completely different flow structure than circular or other non-circular liquid sheets. It was found that the liquid sheet developed a concave-like shape in the presence of the transverse airstream. This phenomenon, named as inflated sheet, was absent in regular circular liquid jets injected into gaseous crossflow. It was revealed the inflated sheet was the main feature of the liquid sheet that made the jet characteristics unique. The flow feature of the inflated sheet structure and its alteration with flow condition was fully examined. Moreover, the width and trajectory of the liquid sheet were quantitatively studied at different Weber numbers and for the constant momentum ratio of 40. It was found that the fluid width could be a useful parameter to distinguish different regimes of the flow.

INTERACTION OF TWO DIFFERENTLY SIZED BUBBLES IN A FREE FIELD

2012 ◽  
Vol 19 ◽  
pp. 180-184
Author(s):  
LUP WAI CHEW ◽  
BOO CHEONG KHOO ◽  
EVERT KLASEBOER ◽  
SIEW-WAN OHL
Keyword(s):  
High Speed ◽  
Free Field ◽  
Real Life ◽  
Separation Distance ◽  
Liquid Jets ◽  
Size Difference ◽  
High Speed Photography ◽  
Distinct Region ◽  
Bubble Interactions ◽  
Multiple Bubbles

The interaction between two different sized (spark created, non-equilibrium) bubbles is studied by using high speed photography. The bubble size ranges from 2 to 7 mm. The experimental results are compared to that of the similar sized bubbles reported in the literature. Interestingly, all the four major behaviors of bubble-bubble interactions (i.e. 'bubble-collapsed' induced liquid jets directed away from each other, liquid jets directed towards each other, bubble coalescence and the 'catapult' effect) are observed which bear much similarity to that found for similar sized bubbles' interaction. The main parameters studied/varied are the size of the bubbles, the dimensionless separation distance and the phase difference between the two bubbles. The results obtained are consistent with the cases of similar sized bubbles reported in the literature, with each type of behavior occupying a distinct region in the graphical plot. This indicates that the results for the (special) similar sized bubbles can be generalized to cases with different sized bubbles. Many of the real life applications such as cavitations corrosions often involve bubbles with significant size difference, thus the present findings are useful in predicting the behavior of multiple bubbles in many situations.

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