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.

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.

Semi-Empirical Correlation to Predict the Sauter Mean Diameter of the Pressure-Swirl Atomizer

2013 ◽  
Author(s):  
Wei Xiao ◽  
Yong Huang
Keyword(s):  
Weber Number ◽  
Droplet Diameter ◽  
Empirical Correlation ◽  
Sauter Mean Diameter ◽  
Operation Condition ◽  
Wide Range ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Semi Empirical ◽  
Pressure Swirl Atomizer

In this study, experiments have been performed to investigate effects of pressure-swirl atomizer geometry on SMD. Different pressure-swirl atomizers were applied to study the effect of geometry on the SMD. Based on the experimental results, an empirical correlation was obtained to relate SMD with the Weber number characterized by film thickness. Meanwhile, a semi-empirical model which was improved from the surface wave breakup theory was established to predict the SMD of pressure-swirl atomizers. The model provides the droplet diameter as a function of atomizer geometry, operation condition and liquid properties. It is proved that the model is qualified for predicting SMD of pressure-swirl atomizers among wide range.

Investigation of Spray Formation and Turbulent Droplet Transport in High Momentum Jet Stabilized Combustor Injection Systems

2020 ◽  
Author(s):  
Dominik Schäfer ◽  
Fabian Hampp ◽  
Oliver Lammel ◽  
Manfred Aigner
Keyword(s):  
Mass Flow ◽  
Gas Turbines ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Air Flow ◽  
High Momentum ◽  
Droplet Distribution ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Abstract This work investigates the influence of coaxial air flow on droplet distribution, velocity, and size generated by a pressure-swirl atomizer. The experiments were performed inside a generic test section with large optical access at atmospheric conditions. The flow conditions replicate the mixing duct sections of high momentum jet stabilized combustors for gas turbines, e.g. high axial air velocities without swirl generation and high preheat temperatures. High momentum jet stabilized combustors based on the FLOX® burner concept are used successfully in gas turbines due to its fuel and load flexibility and very low pollutant emissions. In previous and ongoing studies, different model combustors have been under investigation mainly with the focus of broadening fuel flexibility and operational limits. Operation with different liquid fuel injection systems in high pressure experiments showed a significant impact from the injector shape and injection strategy on the fuel air mixing behavior, the flame position and stability, and thus NOx emissions. This experiment will give a more detailed understanding of the turbulent mixing and interaction of primary and secondary atomization with the surrounding air in such burners. The setup will also allow for the testing of different injection systems for various burner configurations by the variation of injection type, location, fuel, and air flow properties. In the present experiments a pressure-swirl atomizer was set to a constant pressure drop and mass flow. Liquid fuel was replaced by deionized water due to safety concerns. The coaxial air mass flow was preheated up to 473 K and set to bulk velocities of 20 m/s, 50 m/s, and 80 m/s. Particle Image Velocimetry (PIV) was used to characterize the flow field downstream of the point of injection. The droplet size and velocity distributions were quantified by double frame shadow imaging combined with a long-distance microscope with a resolution below 1 μm per pixel. Moreover, the formation of ligaments as well as primary spray break-up was visualized. The results show a significant change of the spatial droplet distribution with increasing co-flow velocity for a given atomizer geometry. The spray cone angle widens at high co-flow velocities due to the formation of a pronounced recirculation zone behind the backward facing step of the injector near the nozzle orifice. This also leads to a change in the initial droplet momentum and the spatial distribution of large droplets. Smaller droplets are concentrated to the center of the spray due to turbulent transport. These findings assist the ongoing developments of liquid fuel injection systems for high momentum jet based combustors and provide validation data for numerical simulations of primary and secondary atomization.

Effect of Dimensionless Numbers on Air Core Diameter of Pressure-Swirl Atomizer

2020 ◽  
Vol 899 ◽  
pp. 22-28
Author(s):  
Zulkifli Abdul Ghaffar ◽  
Salmiah Kasolang ◽  
Ahmad Hussein Abdul Hamid ◽  
Mohd Syazwan Firdaus Mat Rashid
Keyword(s):  
Performance Test ◽  
Operating Conditions ◽  
Spray Angle ◽  
Dimensionless Numbers ◽  
Flow Area ◽  
Core Diameter ◽  
Air Core ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Air core is an important parameter in pressure swirl atomizer since formation of air core determines the thickness of the discharged liquid sheet and the effective flow area of nozzle discharge. This consequently will affect the coefficient of discharge and the spray angle. This study conducted for the investigation of the relation between dimensionless numbers on the air core diameter. Dimensionless numbers are helpful aid for the quantification of independent parameters involving atomizer design and operating conditions simultaneously. Reynolds number, Re and orifice-to-swirl chamber diameter ratio, N are the dimensionless numbers selected for this study. Despite of the availability of study on the effect of dimensionless numbers on air core diameter, more study requires especially for smaller N. An experimental test-rig was constructed to conduct the performance test of the atomizer. Acquired images were analyzed using image-processing software. It was found that N has more significant effect on the change of air core diameter compared to Re. However, it is observed that at Re = 40000, N = 0.07 produces almost similar air core diameter with N = 0.25 at Re < 20000. In contrast, with N = 0.5, air core diameter produces are larger even at Re < 20000. Hence, it can be concluded that both Re and N are important parameters in characterizing the air core diameter in pressure-swirl atomizer.

scholarly journals Experimental and Analytical Investigation on the Variation of Spray Characteristics Along Radial Distance Downstream of a Pressure Swirl Atomizer

1986 ◽  
Vol 108 (3) ◽  
pp. 473-478 ◽  
Author(s):  
Y. H. Zhao ◽  
W. M. Li ◽  
J. S. Chin
Keyword(s):  
Drop Size ◽  
Laser Light ◽  
Radial Distance ◽  
Analytical Investigation ◽  
Laser Light Scattering ◽  
Sauter Mean Diameter ◽  
Spray Characteristics ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

The variation of spray characteristics (Sauter Mean Diameter and Rosin-Rammler drop-size distribution parameter) downstream of a pressure swirl atomizer along radial distance has been measured by laser light scattering technology. An analytical model has been developed that is capable of predicting the variation of spray characteristics along radial distance. A comparison between the prediction and experimental data shows excellent agreement. It shows that the spray model proposed, although relatively simple, is correct and can be used with some expansion and modification to predict more complicated spray systems.

INTERNAL AND NEAR-NOZZLE FLOW OF A PRESSURE-SWIRL ATOMIZER UNDER VARIED FUEL TEMPERATURE

2007 ◽  
Vol 17 (6) ◽  
pp. 529-550 ◽  
Author(s):  
Seoksu Moon ◽  
Choongsik Bae ◽  
Essam F. Abo-Serie ◽  
Jaejoon Choi
Keyword(s):  
Nozzle Flow ◽  
Fuel Temperature ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Study of pressure swirl atomizer with tangential input at design point and outside of design point

2020 ◽  
Vol 32 (12) ◽  
pp. 127113
Author(s):  
Kiumars Khani Aminjan ◽  
Balaram Kundu ◽  
D. D. Ganji
Keyword(s):  
Design Point ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

Studies on air core size in a simplex pressure-swirl atomizer

2017 ◽  
Vol 42 (29) ◽  
pp. 18649-18657 ◽  
Author(s):  
Zhilin Liu ◽  
Yong Huang ◽  
Lei Sun
Keyword(s):  
Core Size ◽  
Air Core ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

A Numerical Approach for the Simulation of Internal Nozzle Flow in a Pressure Swirl Atomizer Using Different Turbulent Models and Towards an Effective Inlet Weber Number

2013 ◽  
Author(s):  
Ahmadreza Abbasi Baharanchi ◽  
Seckin Gokaltun ◽  
Shahla Eshraghi
Keyword(s):  
Weber Number ◽  
Computational Cost ◽  
Internal Flow ◽  
Numerical Approach ◽  
Reynolds Stress Model ◽  
Multiphase Model ◽  
Vof Model ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer

VOF Multiphase model is used to simulate the flow inside a pressure-swirl-atomizer. The capability of the Reynolds Stress Model and variants of the K-ε and K-ω models in modeling of turbulence has been investigated in the commercial computational fluid dynamics (CFD) software FLUENT 6.3. The Implicit scheme available in the volume-of-fluid (VOF) model is used to calculate the interface representation between phases. The atomization characteristics have been investigated as well as the influence of the inlet swirl strength of the internal flow. The numerical results have been successfully validated against experimental data available for the computed parameters. The performance of the RNG K-ε model was found to be satisfactory in reducing the computational cost and introducing an effective Weber number for the flow simulated in this study.

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