Numerical Analyses of Fluid Dynamics of an Atomization Configuration

2002 ◽  
Vol 17 (1) ◽  
pp. 156-166 ◽  
Author(s):  
Q. Xu ◽  
D. Cheng ◽  
G. Trapaga ◽  
N. Yang ◽  
E.J. Lavernia
Keyword(s):  
Gas Flow ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Ambient Pressure ◽  
Delivery Tube ◽  
Compression Waves ◽  
Pressure Region ◽  
High Kinetic Energy ◽  
Dynamic Techniques ◽  
Liquid Delivery

Computational fluid dynamic techniques were used to analyze the gas flow behavior of a typical atomization configuration. The calculated results are summarized as follows. The atomization gas flow at the atomizer's exit may be either subsonic at ambient pressure or sonic at an underexpanded condition, depending on the magnitude of the inlet gas pressure. When the atomization gas separates to become a free annular gas jet, a closed recirculating vortex region is formed between the liquid delivery tube and the annular jet's inner boundary. Upon entering the atomization chamber, an underexpanded sonic gas flow is further accelerated to supersonic velocity during expansion. This pressure adjustment establishes itself in repetitive expansion and compression waves. A certain protrusion of the liquid delivery tube is crucial to obtain a stable subatmospheric pressure region at its exit. The vortex flow under the liquid delivery tube tends to transport liquid metal to the high kinetic energy gas located outside the liquid delivery tube, thereby leading to an efficient atomization.

Modeling of Flow Fields of Different Delivery Chamfers in Spray Forming Process

2014 ◽  
Vol 789 ◽  
pp. 554-559
Author(s):  
Yang Liu ◽  
Zhou Li ◽  
Guo Qing Zhang ◽  
Wen Yong Xu
Keyword(s):  
Flow Field ◽  
Gas Flow ◽  
Fluid Dynamic ◽  
Metal Flow ◽  
Spray Forming ◽  
Operating Pressure ◽  
Delivery Tube ◽  
Forming Process ◽  
Atomization Process ◽  
Sharp Point

The computational fluid dynamic (CFD) software was used to calculate the velocity field in atomization chamber of spray forming equipment. The relationship between melt flow rates, gas aspiration of the atomizer and operating pressure are complex, and the above mentioned parameters are closely related to the atomization process. The influences of different delivery chamfers on gas flow field, which is determined by atomizer structure, were analyzed. Using K-epsilon model with a symmetrical domain, the gas dynamic of different delivery chamfer conditions were investigated. The results indicate that the sharp point of delivery tube causes detachment of flow field, and 56°, 45° and 34° chamfer conditions have same diffusion angle. Gas was aspirated from delivery tube when chamfer was 0°, which is beneficial to liquid metal flow in atomization process.

G106 Fluid dynamic study on radial gas flow behavior in a disk shape planar SOFC channel(1)

2006 ◽  
Vol 2006 (0) ◽  
pp. _G106-a_
Author(s):  
Yoshitaka MUKAI ◽  
Kazumi TSUNODA ◽  
Kazuma SATO ◽  
Motoyasu SASAKI
Keyword(s):  
Gas Flow ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Dynamic Study

scholarly journals G106 Fluid dynamic study on radial gas flow behavior in a disk shape planar SOFC channel(2)

2006 ◽  
Vol 2006 (0) ◽  
pp. _G106-1_-_G106-4_
Author(s):  
Yoshitaka MUKAI ◽  
Kazumi TSUNODA ◽  
Kazuma SATO ◽  
Motoyasu SASAKI
Keyword(s):  
Gas Flow ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Dynamic Study

Multicode Prediction of the Influence of the Exhaust System on the Performance of a Turbocharged Engine

2002 ◽  
Vol 124 (3) ◽  
pp. 695-701 ◽  
Author(s):  
G. Chiatti ◽  
O. Chiavola
Keyword(s):  
Gas Flow ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Engine Performance ◽  
Exhaust System ◽  
One Dimensional ◽  
Fast Processing ◽  
Dimensional Models ◽  
Three Dimensional Models

A multicode approach, based on the simultaneous use of zero-dimensional, one-dimensional, and three-dimensional models, has been developed and tested, and is here applied to predict the thermodynamic and fluid dynamic phenomena that characterize the unsteady gas flow propagation along the exhaust system of a turbocharged four-cylinder engine. The investigation is carried out by applying each model in a different region of the geometry, allowing to obtain detailed information of the flow behavior in complex elements, such as junctions, avoiding the significant limitations that a one-dimensional scheme always introduces, as well as fast processing typical of one-dimensional and zero-dimensional models, devoted to the analysis of ducts and volumes. The effect of the influence of different configurations of the exhaust system on the engine performance is analyzed.

scholarly journals Multiphasic Study of Fluid-Dynamics and the Thermal Behavior of a Steel Ladle during Bottom Gas Injection Using the Eulerian Model

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1082
Author(s):  
Antonio Urióstegui-Hernández ◽  
Pedro Garnica-González ◽  
José Ángel Ramos-Banderas ◽  
Constantin Alberto Hernández-Bocanegra ◽  
Gildardo Solorio-Díaz
Keyword(s):  
Heat Exchange ◽  
Thermal Behavior ◽  
Gas Flow ◽  
Fluid Dynamic ◽  
Steel Slag ◽  
Scale Model ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Steel Ladle ◽  
Physical Scale

In this work, the fluid dynamic and thermal behavior of steel was analyzed during argon gas stirring in a 140-t refining ladle. The Eulerian multiphase mathematical model was used in conjunction with the discrete ordinates (DO) thermal radiation model in a steel-slag-argon system. The model was validated by particle image velocimetry (PIV) and the analysis of the opening of the oil layer in a physical scale model. The effect of Al2O3 and Mg-C as a refractory in the walls was studied, and the Ranz-Marshall and Tomiyama models were compared to determine the heat exchange coefficient. The results indicated that there were no significant differences between these heat exchange models; likewise, the radiation heat transfer model adequately simulated the thermal behavior according to plant measurements, finding a thermal homogenization time of the steel of 2.5 min for a gas flow of 0.45 Nm3·min−1. Finally, both types of refractory kept the temperature of the steel within the ranges recommended in the plant; however, the use of Al2O3 had better heat retention, which would favor refining operations.

Un-Shocked High Amplitude Standing Waves in Wave-Shaped Resonators

2012 ◽  
Author(s):  
Dion Savio Antao ◽  
Bakhtier Farouk
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Ambient Pressure ◽  
Standing Waves ◽  
High Amplitude ◽  
Prime Mover ◽  
Non Linear ◽  
Resonator System ◽  
Cylindrical Resonators ◽  
Linear Nature

A numerical study of non-linear, high amplitude standing waves in non-cylindrical circular resonators is reported here. These waves are shock-less and can generate peak acoustic overpressures that can exceed the ambient pressure by three/four times its nominal value. A high fidelity compressible computational fluid dynamic model is used to simulate the phenomena in cylindrical and arbitrarily shaped axisymmetric resonators. A right circular cylinder and frustum of cone are the two geometries studied. The model is validated using past numerical and experimental results of standing waves in cylindrical resonators. The non-linear nature of the harmonic response of the frustum of cone resonator system is investigated for two different working fluids (carbon dioxide and argon) operating at various values of piston amplitude. The high amplitude non-linear oscillations demonstrated can be used as a prime mover in a variety of applications including thermoacoustic cryocooling.

scholarly journals Squeezing Force of the Magnetorheological Fluid Isolating Damper for Centrifugal Fan in Nuclear Power Plant

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Jin Huang ◽  
Ping Wang ◽  
Guochao Wang
Keyword(s):  
Nuclear Power ◽  
Theoretical Foundation ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Magnetorheological Fluid ◽  
Centrifugal Fan ◽  
Parallel Channel ◽  
Mr Fluid ◽  
Mr Fluids ◽  
Control Devices

Magnetorheological (MR) disk-type isolating dampers are the semi-active control devices that use MR fluids to produce controllable squeezing force. In this paper, the analytical endeavor into the fluid dynamic modeling of an MR isolating damper is reported. The velocity and pressure distribution of an MR fluid operating in an axisymmetric squeeze model are analytically solved using a biviscosity constitutive model. Analytical solutions for the flow behavior of MR fluid flowing through the parallel channel are obtained. The equation for the squeezing force is derived to provide the theoretical foundation for the design of the isolating damper. The result shows that with the increase of the applied magnetic field strength, the squeezing force is increased.

Study of Gas Flow in Micronozzles Using an Unstructured DSMC Method

2009 ◽  
Author(s):  
Ehsan Roohi ◽  
Masoud Darbandi ◽  
Vahid Mirjalili
Keyword(s):  
Boundary Layer ◽  
Knudsen Number ◽  
Gas Flow ◽  
Subsonic Flow ◽  
Flow Behavior ◽  
Boundary Layer Separation ◽  
Back Pressure ◽  
Viscous Force ◽  
Dsmc Method ◽  
Wide Range

The current research uses an unstructured direct simulation Monte Carlo (DSMC) method to numerically investigate supersonic and subsonic flow behavior in micro convergent–divergent nozzle over a wide range of rarefied regimes. The current unstructured DSMC solver has been suitably modified via using uniform distribution of particles, employing proper subcell geometry, and benefiting from an advanced molecular tracking algorithm. Using this solver, we study the effects of back pressure, gas/surface interactions (diffuse/specular reflections), and Knudsen number, on the flow field in micronozzles. We show that high viscous force manifesting in boundary layers prevents supersonic flow formation in the divergent section of nozzles as soon as the Knudsen number increases above a moderate magnitude. In order to accurately simulate subsonic flow at the nozzle outlet, it is necessary to add a buffer zone to the end of nozzle. If we apply the back pressure at the outlet, boundary layer separation is observed and a region of backward flow appears inside the boundary layer while the core region of inviscid flow experiences multiple shock-expansion waves. We also show that the wall boundary layer prevents forming shocks in the divergent part. Alternatively, Mach cores appear at the nozzle center followed by bow shocks and an expansion region.

Behavior of Radial Incompressible Flow in Pneumatic Dimensional Control Systems

2003 ◽  
Vol 125 (5) ◽  
pp. 843-850 ◽  
Author(s):  
G. Roy ◽  
D. Vo-Ngoc ◽  
D. N. Nguyen ◽  
P. Florent
Keyword(s):  
Gas Flow ◽  
Flow Behavior ◽  
Pressure Gauge ◽  
Axisymmetric Flow ◽  
Low Pressure ◽  
Industrial Applications ◽  
Nozzle Geometry ◽  
Machined Surface ◽  
Flow Area ◽  
Simpler Algorithm

The application of pneumatic metrology to control dimensional accuracy on machined parts is based on the measurement of gas flow resistance through a restricted section formed by a jet orifice placed at a small distance away from a machined surface. The backpressure, which is sensed and indicated by a pressure gauge, is calibrated to measure dimensional variations. It has been found that in some typical industrial applications, the nozzles are subject to fouling, e.g., dirt and oil deposits accumulate on their frontal areas, thus requiring more frequent calibration of the apparatus for reliable service. In this paper, a numerical and experimental analysis of the flow behavior in the region between an injection nozzle and a flat surface is presented. The analysis is based on the steady-state axisymmetric flow of an incompressible fluid. The governing equations, coupled with the appropriate boundary conditions, are solved using the SIMPLER algorithm. Results have shown that for the standard nozzle geometry used in industrial applications, an annular low-pressure separated flow area was found to exist near the frontal surface of the nozzle. The existence of this area is believed to be the cause of the nozzle fouling problem. A study of various alternate nozzle geometries has shown that this low-pressure recirculation area can be eliminated quite readily. Well-designed chamfered, rounded, and reduced frontal area nozzles have all reduced or eliminated the separated recirculation flow area. It has been noted, however, that rounded nozzles may adversely cause a reduction in apparatus sensitivity.

scholarly journals Thermos-Solid-Gas Coupling Dynamic Model and Numerical Simulation of Coal Containing Gas

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xiao Fukun ◽  
Meng Xin ◽  
Li Lianchong ◽  
Liu Jianfeng ◽  
Liu Gang ◽  
...  
Keyword(s):  
Principal Stress ◽  
Dynamic Model ◽  
Gas Flow ◽  
Flow Behavior ◽  
Coupling Model ◽  
Gas Pressure ◽  
Permeability Model ◽  
Gas Seepage ◽  
Coupling Dynamic ◽  
Coupling Dynamic Model

Based on gas seepage characteristics and the basic thermo-solid-gas coupling theory, the porosity model and the dynamic permeability model of coal body containing gas were derived. Based on the relationship between gas pressure, principal stress and temperature, and gas seepage, the thermo-solid-gas coupling dynamic model was established. Initial values and boundary conditions for the model were determined. Numerical simulations using this model were done to predict the gas flow behavior of a gassy coal sample. By using the thermo-solid-gas coupling model, the gas pressure, temperature, and principal stress influence, the change law of the pressure field, displacement field, stress field, temperature field, and permeability were numerically simulated. Research results show the following: (1) Gas pressure and displacement from the top to the end of the model gradually reduce, and stress from the top to the end gradually increases. The average permeability of the Y Z section of the model tends to decrease with the rise of the gas pressure, and the decrease amplitude slows down from the top of the model to the bottom. (2) When the principal stress and temperature are constant, the permeability decreases first and then flattens with the gas pressure. The permeability increases with the decrease of temperature while the gas pressure and principal stress remain unchanged.

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