scholarly journals Energy equilibrium analysis in the effervescent atomization

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 925-932
Author(s):  
Runze Duan ◽  
Ziwei Feng ◽  
Hongbin Duan ◽  
Huiru Qu ◽  
Liting Tian ◽  
...  
Keyword(s):  
Surface Tension ◽  
Flow Characteristics ◽  
Equilibrium Analysis ◽  
Liquid Viscosity ◽  
Sauter Mean Diameter ◽  
Mean Diameter ◽  
Compressed Gas ◽  
Energy Equilibrium ◽  
Swirl Atomizer ◽  
Gas Expansion

Abstract In this paper, the flow characteristics and energy equilibrium analysis of the effervescent atomization had been investigated theoretically and experimentally. The effect of the gas–liquid rate (GLR from 0.04 to 0.15) on the atomization stability was revealed. When the GLR was small, the atomization was unstable. The atomization was gradually stable with an increase in the GLR. The optimal atomization region can be obtained. The Sauter mean diameter (SMD) of the droplets was measured by the phase Doppler analyzer. The SMD decreases with an increase in the GLR. The energy equilibrium analysis was investigated for the swirl atomizer theoretically and experimentally. The results show that the energy dissipation terms are mainly compressed gas expansion, liquid viscosity dissipation, and resistance losses. However, the ratio of the spray kinetic energy and the surface tension energy to the total energy is small.

Bubble Entrapment in Sprayed Films

2014 ◽  
Author(s):  
A. Dalili ◽  
S. Chandra ◽  
J. Mostaghimi ◽  
H. T. Charles Fan ◽  
J. C. Simmer
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
The Other ◽  
Bubble Motion ◽  
Sauter Mean Diameter ◽  
Glass Substrates ◽  
Buoyancy Forces ◽  
Mean Diameter ◽  
Imagej Software ◽  
Bubble Movement

A compressed air sprayer was used to spray model paint onto two glass substrates at the same time. Afterwards, one glass substrate was placed on a LED light source and still photographs were taken from the top using a DSLR camera with a timer system. The other substrate was put on a balance to record weight. Pictures and weight measurements were taken at 5 second intervals for 15 minutes. The sprayed film thickness was varied. The pictures were analyzed using ImageJ software. Bubble Count vs. Time, Sauter Mean Diameter (SMD) of Bubbles vs. Time as well as Weight vs. Time was plotted. It was seen that the pace of weight loss was faster for thinner films. The rate of bubble escape also depended on film thickness. It took a longer time for thicker films to lose the bubbles entrapped in them. In the first 30 seconds, large bubbles escaped due to buoyancy forces and afterwards surface-tension driven flows became dominant. There was also a lot of bubble movement in thicker films. The effect of gravity was studied as well. Gravity did not affect the bubble escape rate since a downward facing film had the same bubble count as an upward facing film confirming that bubble motion was not due to buoyancy forces alone. However, the SMD of bubbles in a downward facing film was larger than an upward facing film. Buoyancy is not a factor in bubble escape from the downward facing film and only surface-tension driven flows play a role.

Numerical investigation of the full-cone spray structure and characteristics provided by a jet-swirl atomizer

2019 ◽  
Vol 233 (15) ◽  
pp. 5788-5800 ◽  
Author(s):  
Mohammad Amin Hassani ◽  
Abbas Elkaie ◽  
Maziar Shafaee
Keyword(s):  
Spray Parameters ◽  
Sauter Mean Diameter ◽  
Spray Cone ◽  
Spray Tip Penetration ◽  
Spray Structure ◽  
Mean Diameter ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Breakup Model ◽  
Good Agreement

Jet-swirl atomizers are one of the pressure-swirl atomizers that produce full-cone spray. Although many hollow-cone pressure-swirl sprays have been studied, characteristic investigation of pressure-swirl full-cone sprays are limited to a few experimental, analytical, and numerical works where each of them investigate some of the main spray parameters. The few existing numerical studies are limited to calculate the coefficient of discharge and spray cone angle. Current numerical study investigate a newly developed jet-swirl atomizer with pressure-swirl full-cone spray, which considers other important full-cone spray characteristics including Sauter mean diameter, D10, and spray tip penetration along with the spray structure. In this study, a full-cone spray based on a newly developed jet-swirl injector is numerically simulated and analyzed using sprayFoam solver in the OpenFOAM 4.1 software. The existing code of the solver is developed and its dictionary is modified. The C+ + Sauter mean diameter and D10 codes on the cross-sectional surface are developed and this feature is added to the sprayFoam solver. The pre-published experimental and current work numerical results were in good agreement. In the simulation process, blob sheet model is used for the spray primary breakup. Two models including Taylor analogy breakup and Reitz–Diwakar have been used for the secondary breakup of the developed jet-swirl atomizer. This work shows that the results of the Reitz–Diwakar model are close to that of the Taylor analogy breakup model. The time-varying results of Sauter mean diameter, D10, and spray tip penetration are found to be in good agreement in both models. The results show that the Reitz–Diwakar model is stabilized somewhat later than the Taylor analogy breakup model. The simulated spray structure shows that the density of droplets is higher in the spray center region and this density is gradually reduced through the radial direction. The results along the radius show that the diameter of the droplets becomes larger while moving away from the center of the spray.

scholarly journals Effect of the two-phase hybrid mode of effervescent atomizer on the atomization characteristics

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 960-965
Author(s):  
Liansheng Liu ◽  
Na Pei ◽  
Ruolin Zhao ◽  
Liang Tian ◽  
Runze Duan ◽  
...  
Keyword(s):  
Cone Angle ◽  
Great Influence ◽  
Design Parameters ◽  
Sauter Mean Diameter ◽  
Hybrid Mode ◽  
Two Phase ◽  
Mean Diameter ◽  
Effervescent Atomizer ◽  
Atomization Characteristics ◽  
Swirl Atomizer

Abstract In this paper, the atomization characteristics of an effervescent atomizer were investigated. The velocity, Sauter Mean Diameter (SMD) and atomization cone angle of the droplets were measured using the Phase Doppler Analyzer (PDA) to discuss the effect of different design parameters. The results showed that the atomization was unstable at a small Gas-Liquid Rate (GLR) while the atomization proved gradually by increasing the GLR. The optimal atomization region was at a GLR=0.1. In the atomization process, there existed a typical velocity distribution for the swirl atomizer. The design parameters of atomizer provided a great influence on the Sauter Mean Diameter (SMD) and atomization cone angle. The experiment results showed that some droplets had negative velocities.

scholarly journals A Computational Fluid Dynamics-based Correlation to Predict Droplet Sauter Mean Diameter for Σ− Yliq Atomization Model in Pressure Swirl Atomizer

2021 ◽  
Vol 6 (7) ◽  
pp. 69-76
Author(s):  
Sherry K. Amedorme ◽  
Joseph Apodi
Keyword(s):  
Fluid Dynamics ◽  
Fuel Injection ◽  
Liquid Velocity ◽  
Operating Conditions ◽  
Sauter Mean Diameter ◽  
Design Variables ◽  
Mean Diameter ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Liquid atomization is crucial to ensure efficient combustion as it is an inherent part of the injector system. The combustion of fuels relies on effective atomization to increase the surface area of the fuel and consequently achieve high rates of mixing and evaporation. Pressure swirl atomizers are inexpensive and reliable type of atomizer for fuel injection owing to its superior atomization characteristics and relatively simple geometry. The Sauter mean diameter (SMD) of atomizer contributes significantly to the combustion chamber performance. This paper presents a two-step strategy to predict droplet SMD for atomisation model in pressure swirl atomizer through the combination of experimentally validated Computation Fluid Dynamics (CFD) and Optimal Latin Hypercubes (OLHC) Design of Experiments (DoE) techniques. A three-dimensional Eulerian two-phase CFD model is developed to account for liquid and gas phases as a single continuum with high-density variation at large Reynolds and Weber numbers and validated against experimental measurements, before being employed to carry out a parametric study involving operating conditions and fluid properties of the pressure swirl atomizer. The atomizer is then represented in terms of four design variables, namely liquid viscosity, liquid velocity, surface tension and atomizer exit diameter. An 87-point OLHC DoE is constructed within the design variables space using a permutation genetic algorithm resulting in an accurate SMD prediction. Results show the newly developed SMD prediction is found to be superior compared with existing correlations and indicate significant improvement in the droplets SMD.

scholarly journals The effect of viscosity and surface tension on inkjet printed picoliter dots

RSC Advances ◽  
2019 ◽  
Vol 9 (54) ◽  
pp. 31708-31719 ◽  
Author(s):  
Sarah Krainer ◽  
Chris Smit ◽  
Ulrich Hirn
Keyword(s):  
Surface Tension ◽  
Inkjet Printing ◽  
Liquid Viscosity

In this study, we investigated the effect of liquid viscosity and surface tension for inkjet printing on porous cellulose sheets.

scholarly journals Atomization Quality of Twin Fluid Atomizers for Gas Turbines

1982 ◽  
Author(s):  
M. M. Elkotb ◽  
M. A. Elsayed Mahdy ◽  
M. E. Montaser
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Gas Turbines ◽  
Cone Angle ◽  
Droplet Size Distribution ◽  
Diameter Ratio ◽  
Air Pressure ◽  
Sauter Mean Diameter ◽  
Flow Number ◽  
Mean Diameter

A detailed investigation of the effect of nozzle/needle diameter ratio, normal fuel area, swirler degree, air pressure, fuel pressure on flow number, cone angle and droplet size distribution of external mixing twin fluid atomizers is given in this paper. Forty atomizers have been constructed to prevent mutual effect of various parameters. Flow number and cone angle are found to increase with nozzle/diameter ratio, and to decrease with the increase of air pressure. Optimum fuel flow is obtained at swirler angle 30-deg, while cone angle increases with increase of swirler angle. Sauter mean diameter decreases with the increase of air pressure and decrease of fuel pressure. Suitable functions are derived for droplet size distribution, Sauter mean diameter, and flow number. They are suitable to predict the geometry of the atomizer and to be used also in a prediction model for the calculation of fuel concentration and heat release.

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