scholarly journals Study of liquid jet instability by confocal microscopy

2012 ◽  
Vol 83 (7) ◽  
pp. 073104 ◽  
Author(s):  
Lisong Yang ◽  
Leanne J. Adamson ◽  
Colin D. Bain
Keyword(s):  
Confocal Microscopy ◽  
Liquid Jet ◽  
Jet Instability

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.

Liquid Jet Instability and Atomization in a Coaxial Gas Stream

2000 ◽  
Vol 32 (1) ◽  
pp. 275-308 ◽  
Author(s):  
J. C. Lasheras ◽  
E. J. Hopfinger
Keyword(s):  
Liquid Jet ◽  
Jet Instability

Model for the initiation of atomization in a high-speed laminar liquid jet

2014 ◽  
Vol 757 ◽  
pp. 665-700 ◽  
Author(s):  
Akira Umemura
Keyword(s):  
Shear Layer ◽  
Nozzle Exit ◽  
High Speed ◽  
Capillary Waves ◽  
Liquid Jet ◽  
Nozzle Wall ◽  
Jet Instability ◽  
Circular Nozzle ◽  
Layer Flow ◽  
Liquid Shear

AbstractA laminar water jet issuing at high speed from a short circular nozzle into air exhibits various instability features at different distances from the nozzle exit. Near the exit, the effects of gaseous friction and pressure are relatively weak. Deformation of the jet surface in this region is mainly due to the instability of a thin liquid shear layer flow, which relaxes from the velocity profile produced by the nozzle wall. In this paper, a model for this type of instability based on linear stability analysis is investigated to describe the process initiating the formation of liquid ligaments disintegrating into fine droplets near the nozzle exit. The modelling comprises identifying unstable waves excitable in the liquid shear layer and exploring a self-destabilizing mechanism by which unstable waves responsible for the formation of liquid ligaments are naturally reproduced from the upstream-propagating capillary waves produced by the growth of the unstable waves themselves. An expression for the location of ligament formation onset is derived that can be compared with experiments. The model also explains changes in jet instability features away from the nozzle exit and for very short nozzles.

Experiments on liquid jet instability

1970 ◽  
Vol 40 (3) ◽  
pp. 495-511 ◽  
Author(s):  
E. F. Goedde ◽  
M. C. Yuen
Keyword(s):  
Wave Number ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Audio Frequency ◽  
Linear Effect ◽  
Jet Instability ◽  
Non Linear ◽  
Linear Effects ◽  
The Difference ◽  
Time Sequences

The capillary instability of vertical liquid jets of different viscosities have been examined by imposing audio-frequency disturbances. Real time sequences of photographs allow a direct measurement of growth rates of disturbances of various wavelengths. Results show that in general non-linear effects dominate the growth processes. This is in agreement with Yuen's analysis. The growth rate of the difference between the neck and the swell, however, agrees well with the linearized analysis of Rayleigh and Chandrasekhar. The non-linear effect causes a liquid jet to disintegrate into drops with ligaments in between. The sizes of the ligaments decrease with increasing wave-number. The subsequent roll up of the ligament into droplet, the eventual coalescing of the droplet with the main drop and drop oscillation have also been studied.

A non-linear model for the atomization of a swirling viscous liquid jet

2008 ◽  
Vol 222 (11) ◽  
pp. 2137-2145
Author(s):  
E A Ibrahim ◽  
T L Williams
Keyword(s):  
Viscous Liquid ◽  
Numerical Solutions ◽  
Mathematical Formulation ◽  
Wave Number ◽  
Liquid Jet ◽  
Jet Instability ◽  
Viscous Forces ◽  
Swirl Injectors ◽  
Satellite Drops ◽  
Surface Disturbances

The instability and consequent atomization of a swirling viscous liquid jet emanated into gaseous surroundings and subjected to periodical surface disturbances is modelled and investigated. The theoretical analysis is based on a simplified mathematical formulation of the continuity and momentum equations in their conservative forms. Numerical solutions of the governing equations along with appropriate initial and boundary conditions are obtained through a robust finite-difference scheme. The computations yield real-time evolution of the interfacial profile and subsequent breakup characteristics of the liquid jet. It is found that the jet disintegrates into main and satellite drops, under all the conditions considered in the present study. The swirl enhances the instability of the jet and causes radial stretching of the main drops, whereas the satellite drops exhibit axial elongation. Increasing viscosity hinders jet instability and leads to main and satellite drop deformations that are similar to those produced by the swirl. The sizes of both main and satellite drops are diminished at higher disturbance wave numbers. A greater swirl strength induces a higher dominant wave number, and hence a reduced size of resultant main and satellite drops. Larger satellite drops and smaller main drops are produced as viscous forces are increased. The present model could be used as a guide for designing swirl injectors.

scholarly journals On the thermal instability of supercavitating liquid jet surrounded by coaxial rotary gas

2021 ◽  
Vol 37 ◽  
pp. 551-565
Author(s):  
Ming Lü ◽  
Zhi Ning
Keyword(s):  
Mathematical Model ◽  
Temperature Gradient ◽  
Thermal Instability ◽  
Dominant Frequency ◽  
Liquid Jet ◽  
Liquid Temperature ◽  
Jet Instability ◽  
Jet Stability ◽  
Effects Of Temperature ◽  
The Mathematical Model

Abstract Based on the jet stability theory, under the conditions of gas rotation, fluid compressibility and supercavitation, this paper gives the mathematical model describing the thermal instability of supercavitating liquid jet surrounded by a coaxial rotary gas, and the corresponding numerical method for solving the mathematical model is proposed and verified by the data in reference. Then, this paper analyzes the effects of gas–liquid temperature differences and temperature gradients on jet instability, and studies the thermal stability of supercavitating jet. The results show that the maximum disturbance growth rate, the dominant frequency and the maximum disturbance wave numbers increase linearly with the increase of gas–liquid temperature differences. The existence of temperature gradient inside the jet makes the effects of temperature differences on jet instability more obvious. The temperature gradient will inhibit the effect of supercavitation on jet instability, while gas–liquid temperature difference will promote the effect of supercavitation on jet instability.

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