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.

Experimental investigation on fluid structure and full-cone spray characteristics of a jet-swirl atomizer using shadowgraph technique

2021 ◽  
pp. 095441002110376
Author(s):  
Mazyar Shafaee ◽  
Abbas Elkaie ◽  
Mohammad Amin Hassani
Keyword(s):  
Nozzle Exit ◽  
Uniform Structure ◽  
Spray Parameters ◽  
Number Density ◽  
Spray Characteristics ◽  
Spray Cone ◽  
Fluid Structure ◽  
Spray Density ◽  
Mean Diameter ◽  
Swirl Atomizer

Full-cone spray is quite important in spray cooling and catalytic combustion applications; however, it is not extensively studied. Besides, the liquid spray is relatively a non-uniform structure especially along longitudinal axis which includes different sizes and distribution of droplets. The few published experimental studies are limited to calculate some of the spray characteristics on a certain plane located downstream of the nozzle exit. Therefore, the spray parameters representing fluid structure, droplets mean diameter, and their distribution in different cross sections from nozzle exit are considered in this study. Accordingly, a jet-swirl atomizer with pressure-swirl full-cone spray is investigated where all important full-cone spray characteristics are considered at different planes from nozzle exit. The spray images are obtained with a shadowgraph technique and are analyzed to obtain the Sauter mean diameter (SMD), D10, and droplet size distribution along with the spray structure, spray cone angle, and discharge coefficient. The experimental results are verified based on the pre-published numerical studies on the same atomizer. The experimental and numerical results show good agreement. Moreover, the results show that the SMD is increased by moving away from center of spray to its edges, and the droplets number density is increased in central regions. The increased droplets number density leads to the greater external forces which create smaller droplets. In contrast, larger particles exist in peripheral parts due to the less droplets concentration. Furthermore, and far away from the exit nozzle, the SMD values are decreased due to the increased aerodynamic forces and oscillations. The droplets dispersion including spray density in radial and axial directions is also observed using spray density images.

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.

Experimental Study of Superheated Kerosene Jet Fuel Sprays From a Pressure-Swirl Nozzle

2017 ◽  
Author(s):  
Shaji S. Manipurath
Keyword(s):  
Laser Sheet ◽  
Cone Angle ◽  
Test Facility ◽  
Chamber Pressure ◽  
Engine Fuel ◽  
Fuel Temperature ◽  
Solid Cone ◽  
Spray Cone ◽  
Spray Structure ◽  
Pressure Swirl

The development of higher thermal stability fuels and the development of onboard fuel deoxygenation systems may permit the preheating of fuel up to about 755 K before the onset of pyrolysis. At a sufficiently high fuel temperature for a given combustion chamber pressure, the flash vaporization of liquid or supercritical state fuel can ensue upon injection into the chamber. The performance of standard aviation turbine engine fuel nozzles, designed for mechanically breaking up liquid sprays, may thus be significantly altered by the employment of severely preheated fuel. An evaluation of heated and superheated Jet A-1 sprays from a pressure-swirl atomizer was implemented in a purpose-built test facility. Laser sheet imaging of the spray yielded simultaneous axial cross-sectional maps of Mie-scatter and fluorescence signals. In addition, particle image velocimetry was also used to measure the spray droplet velocity-field. The results indicated that increasing the fuel’s dimensionless level of superheat ΔT* from −1.8 to 0.6 yielded significant changes in the spray structure; specifically, finer droplet sizes, a more uniform dropsize distribution across the spray, increased spray cone angle till about ΔT* = −0.8 followed by a contraction thereafter, marginally increased spray penetration, and significantly higher localised near nozzle tip droplet velocities. The measurements supported the hypothesis that the initial hollow-cone spray structure evolves to a near solid-cone structure with a central vapour core as the fuel is superheated.

scholarly journals Spray and atomization characteristics of gas-centered swirl coaxial injectors

2016 ◽  
Vol 9 (2) ◽  
pp. 127-140 ◽  
Author(s):  
Rahul Anand ◽  
PR Ajayalal ◽  
Vikash Kumar ◽  
A Salih ◽  
K Nandakumar
Keyword(s):  
Rocket Engine ◽  
Cone Angle ◽  
Spray Angle ◽  
Rocket Engines ◽  
Sauter Mean Diameter ◽  
Swirl Number ◽  
Spray Cone ◽  
Mean Diameter ◽  
Atomization Characteristics ◽  
Coaxial Injector

To achieve uniform and efficient combustion in a rocket engine, a fine uniform spray is needed. The same is achieved by designing an injector with good atomization characteristics. Gas-centered swirl coaxial (GCSC) injector elements have been preferred recently in liquid rocket engines because of an inherent capability to dampen the pressure oscillations in the thrust chamber. The gas-centered swirl coaxial injector chosen for this study is proposed to be used in a semi-cryogenic rocket engine operating with oxidizer rich hot exhaust gases from the pre-burner and liquid kerosene as fuel. In this paper, nine different configurations of gas-centered swirl coaxial injector, sorted out by studying the spray angle and coefficient of discharge with swirl number varying from 9 to 20 and recess ratio of 0.5, 1, and 1.5 are investigated for their atomization characteristics. Spray uniformity, spray cone angle, and droplet size in terms of Sauter mean diameter and mass median diameter are studied at various momentum flux ratios for all configurations. Sauter mean diameter is almost independent of recess ratio, whereas cone angle was inversely proportional to the recess ratio. A finer atomization was observed for injectors of high swirl number but the pressure drop also increased to achieve the same flow rate. An injector of medium swirl number and recess ratio of 1.5 is deemed most fit for above-mentioned application.

scholarly journals Spray structure of a pressure-swirl atomizer for combustion applications

2012 ◽  
Vol 25 ◽  
pp. 01010 ◽  
Author(s):  
Lukas Durdina ◽  
Jan Jedelsky ◽  
Miroslav Jicha
Keyword(s):  
Spray Structure ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

scholarly journals 2D and 3D numerical modelling of internal flow of Pressure-swirl atomizer

2019 ◽  
Vol 213 ◽  
pp. 02055
Author(s):  
Milan Maly ◽  
Jaroslav Slama ◽  
Marcel Sapik ◽  
Jan Jedelsky
Keyword(s):  
Numerical Models ◽  
Internal Flow ◽  
Liquid Sheet ◽  
Spray Cone ◽  
Air Core ◽  
Swirl Velocity ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
2D And 3D ◽  
Pressure Swirl Atomizer

This paper compares 2D axisymmetric and 3D numerical models used to predict the internal flow of a pressure-swirl atomizer using a commercial software Ansys Fluent 18.1. The computed results are compared with experimental data in terms of spray cone angle (SCA), discharge coefficient (CD), internal air-core dimensions and swirl velocity profile. The swirl velocity was experimentally studied using a Laser Doppler Anemometry in a scaled transparent model of the atomizer. The internal air-core was visualized at high temporal and spatial resolution by a high-speed camera with backlit illumination. The internal flow was numerically treated as transient two-phase flow. The gas-liquid interface was captured with Volume of Fluid scheme. The numerical solver used both laminar and turbulent approach. Turbulence was modelled using k-ε, k-ω, Reynolds Stress model (RSM) and coarse Large Eddy Simulation (LES). The laminar solver was capable to predict all the parameters with an error less than 5% compared with the experimental results in both 2D and 3D simulation. However, it overpredicted the velocity of the discharged liquid sheet. The LES model performed similarly to the laminar solver, but the liquid sheet velocity was 10% lower. The two-equation models k-ε and k-ω overpredicted the turbulence viscosity and the internal air-core was not predicted.

Experimental Investigations of Spray Characteristics of a Pressure-Swirl Atomizer

2019 ◽  
Vol 234 (5) ◽  
pp. 643-654 ◽  
Author(s):  
Xiongjie Fan ◽  
Cunxi Liu ◽  
Yong Mu ◽  
Haitao Lu ◽  
Jinhu Yang ◽  
...  
Keyword(s):  
Surface Wave ◽  
Liquid Film ◽  
Fuel Temperature ◽  
Spray Characteristics ◽  
Spray Cone ◽  
Breakup Length ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
The Impact ◽  
Pressure Swirl Atomizer

Spray characteristics of a pressure-swirl atomizer are investigated using high-speed shadowgraph technique under different pressure drops (Δ P) and fuel temperatures ( T). An image processing method is developed using MATLAB. The results illustrate that the mass flow rate climbs with the increase of Δ P, while the discharge coefficient ( Cd) decreases firstly and then climbs with the increase of Δ P. Δ P has larger effect on the cone angle relative to fuel temperature. With the increase of Δ P, the shape of liquid film changes from ‘onion’ to ‘tulip’ and finally be fully developed spray cone. Meanwhile, the surface of liquid film becomes smoother with the increase of Δ P. The average breakup length climbs, then decreases to nearly a constant value with the increase of Δ P, which is induced by the “Impact wave,” surface wave, and turbulent energy. There are little differences on the shape of the liquid film under different temperatures, and temperature has different influence on breakup length under different Δ P. Both the fuel temperature and Δ P have significant impact on the surface wavelength ( λ) and velocities ( U, V) of surface wave. The width of fuel stream becomes larger with the increase of Δ P and fuel temperature. The results can further deepen the understanding of spray characteristics of pressure-swirl atomizer.

Numerical Analysis of Pressure Swirl Atomizer

2015 ◽  
Vol 798 ◽  
pp. 190-194
Author(s):  
Mehmet Kahraman ◽  
Guven Komurgoz ◽  
Ibrahim Ozkol
Keyword(s):  
Cone Angle ◽  
Computational Cost ◽  
Internal Flow ◽  
Combustion Engines ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Atomization quality of liquids has a great importance on the performance of combustion engines. In this study the internal flow phenome of pressure swirl atomizer is investigated by using numerical method. The design of swirl atomizer is performed based on the requested atomizer characteristics which are sauter mean diamer (SMD), spray cone angle and break up length. Prediction and understanding of liquid film dynamics in the atomizer inside are the fundamental ways to explore atomizer performance. The purpose of this study is to estimate the air core size and film thickness in pressure swirl atomizer by setting single phase numeric computations. This article concludes that the CFD validated swirl atomizer design can be achieved with the lower computational cost using stream function methodology.

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.

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