scholarly journals Conical Two-Phase Swirl Flow Atomizers—Numerical and Experimental Study

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1745
Author(s):  
Marek Ochowiak ◽  
Daniel Janecki ◽  
Andżelika Krupińska ◽  
Sylwia Włodarczak ◽  
Tomasz Wilk ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Gas Flow ◽  
Experimental Studies ◽  
Swirl Flow ◽  
Spray Angle ◽  
Operational Parameters ◽  
Two Phase ◽  
Additional Information ◽  
Swirl Chamber ◽  
Computational Fluid Dynamics Cfd

This paper presents the results of numerical simulations for the developed and discussed conical two-phase atomizers with swirl flow, differing in the ratio of the height of the swirl chamber to its diameter. Experiments were carried out for SAN-1 with HS/DS = 1 and SAN-2 with HS/DS = 4 atomizers. The study was conducted over a range of Reynolds number for liquid ReL = (1400; 5650) and for gas ReG = (2970; 9900). Numerical calculations were performed with the use of computational fluid dynamics (CFD), which were verified on the basis of experimental data. Based on the analysis of experimental studies and simulations results the influence of operational parameters and changes of the atomizer geometry on the generated spray was demonstrated. As the gas flow rate increased and the swirl chamber height decreased, the spray angle increased. Higher velocity values of the liquid and greater turbulence occur in the center of the spray. The flow inside the atomizer determines the nature of the spray obtained. The geometry of the swirl chamber influences the air core formed inside the atomizer, and this determines the atomization effect. The results of numerical simulations not only confirm the results of experimental studies, but also provide additional information on internal and external fluid flow.

Numerical Simulation of Bubble Formation in Co-Flowing Mercury

2008 ◽  
Author(s):  
Ashraf Ibrahim ◽  
Mark Wendel ◽  
David Felde ◽  
Bernard Riemer
Keyword(s):  
Acoustic Waves ◽  
Bubble Growth ◽  
Gas Flow ◽  
Bubble Formation ◽  
Science Center ◽  
Proton Radiography ◽  
Two Phase ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Bubble Sizes

In this work, we present computational fluid dynamics (CFD) simulations of helium bubble formation and detachment at a submerged needle in stagnant and co-flowing mercury. Since mercury is opaque, visualization of internal gas bubbles was done with proton radiography (pRad) at the Los Alamos Neutron Science Center (LANSCE2). The acoustic waves emitted at the time of detachment and during subsequent oscillations of the bubble were recorded with a microphone. The Volume of Fluid (VOF) model was used to simulate the unsteady two-phase flow of gas injection in mercury. The VOF model is validated by comparing detailed bubble sizes and shapes at various stages of the bubble growth and detachment, with the experimental measurements at 1.66 mg/min helium gas flow rate and different mercury velocities. The experimental and computational results show a two-stage bubble formation in stagnant mercury. The first stage involves growing bubble around the needle, and the second follows as the buoyancy overcomes wall adhesion. The comparison of predicted and measured bubble sizes and shapes at various stages of the bubble growth and detachment is in good agreement.

scholarly journals Experimental and Numerical Studies of Hydrodynamics of Gas Flow through Orthogonal Networks

2018 ◽  
Author(s):  
Grzegorz Wałowski
Keyword(s):  
Kinetic Energy ◽  
Dissipation Rate ◽  
Gas Flow ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Cfd Modeling ◽  
Numerical Studies ◽  
Isotropic Porous Material ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through

Simulation programs contain Computational Fluid Dynamics - CFD codes and are a useful tool used for gas flow through porous materials. Conducting numerical simulations allows for detailed analysis of hydrodynamic phenomena. The results of numerical modeling should always be verifiable based on experimental data. Only their compliance with the results of experimental tests is a determinant of the correctness of the applied method. As part of the work, experimental studies of hydrodynamics of gas flow through an isotropic porous material were carried out and numerical simulation for material of the same shape was used. In the CFD modeling Kolmogorov's hypothesis for the transport of kinetic energy of turbulence k and transport of dissipation rate of kinetic energy of turbulence ε was used.

scholarly journals Dynamics of dry spots in the liquid film moved by the gas flow in the mini-channel under intensive local heating

2018 ◽  
Vol 194 ◽  
pp. 01059
Author(s):  
Egor Tkachenko
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Gas Flow ◽  
Local Heating ◽  
Experimental Studies ◽  
Heater Surface ◽  
Two Phase ◽  
Heat Transfer Crisis ◽  
Typical Size ◽  
Dry Spot

Experimental studies of hydrodynamics and the heat transfer crisis were carried out for a two-phase stratified flow in a mini-channel with intensive heating from a heat source of 1x1 cm2. It has been established that as the heat flow increases, the total area of dry spots on the heater increases, but when a certain temperature of the heater surface reaches ≈100 °C, the area of dry spots begins to decrease. With the help of high-speed visualization (shooting speed 100000 frames per second), several stages of formation of a dry spot (a typical size of the order of 100 microns) were isolated. It was found that at a heat flux of 450 W/cm2 about 1 million dry spots per 1 second are formed and washed on the surface of the heater (1 cm2). The speed of the contact line when dry spot is forming reaches 10 m/s.

CFD STUDY OF CYCLONE PERFORMANCE: EFFECT OF INLET SECTION ANGLE AND PARTICLE SIZE DISTRIBUTION

2016 ◽  
Vol 78 (6-4) ◽  
Author(s):  
Ratchanon Piemjaiswang ◽  
Kongpob Ratanathammapan ◽  
Prapan Kunchonthara ◽  
Pornpote Piumsomboon ◽  
Benjapon Chalermsinsuwan
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Collection Efficiency ◽  
Solid Particles ◽  
Inlet Section ◽  
Two Phase ◽  
Performance Effect ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Angle ◽  
Numerical Simulation Technique

A numerical simulation technique was employed to model the two phase flow in cyclones using computational fluid dynamics (CFD). Three different inlet angles of cyclone, including 45, 0 and -45 degrees were compared to describe the efficiency of the conventional cyclone with the modified inlet angle ones. The results showed that the interaction between solid particles in dilute system could be neglected. The pressure drop was decreased when the inlet angle of the cyclone increased. The cyclone with 45 degrees inlet angle tended to have the lowest pressure drop. The collection efficiency was improved with 45 degrees inlet angle due to high swirling motion of gas flow. 

scholarly journals Numerical Study of Gravity Effects on Phase Separation in a Swirl Chamber

2016 ◽  
Author(s):  
Chao-Tsung Hsiao ◽  
Jingsen Ma ◽  
Georges L. Chahine
Keyword(s):  
Two Phase Flow ◽  
Numerical Study ◽  
Swirl Flow ◽  
Phase Flow ◽  
Cylinder Axis ◽  
Two Phase ◽  
Swirl Chamber ◽  
Gravity Effects ◽  
Acceleration Of Gravity ◽  
Phase Separator

The effects of gravity on a phase separator are studied numerically using an Eulerian/Lagrangian two-phase flow approach. The separator utilizes high intensity swirl to separate bubbles from the liquid. The two-phase flow enters tangentially a cylindrical swirl chamber and rotate around the cylinder axis. On earth, as the bubbles are captured by the vortex formed inside the swirl chamber due to the centripetal force, they also experience the buoyancy force due to gravity. In a reduced or zero gravity environment buoyancy is reduced or inexistent and capture of the bubbles by the vortex is modified. The present numerical simulations enable study of the relative importance of the acceleration of gravity on the bubble capture by the swirl flow in the separator. In absence of gravity, the bubbles get stratified depending on their sizes, with the larger bubbles entering the core region earlier than the smaller ones. However in presence of gravity, stratification is more complex as the two acceleration fields — due to gravity and to rotation — compete or combine during the bubble capture.

scholarly journals The Two-Phase Conical Swirl Atomizers: Spray Characteristics

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3416 ◽  
Author(s):  
Marek Ochowiak ◽  
Andżelika Krupińska ◽  
Sylwia Włodarczak ◽  
Magdalena Matuszak ◽  
Małgorzata Markowska ◽  
...  
Keyword(s):  
Flow Rate ◽  
Discharge Coefficient ◽  
Experimental Studies ◽  
Central Area ◽  
Spray Angle ◽  
Sauter Mean Diameter ◽  
Spray Characteristics ◽  
Two Phase ◽  
Mean Diameter ◽  
The Impact

This paper presents the results of experimental studies on two-phase conical swirl atomizers. The impact of various atomizer geometries and different operational parameters of the atomization process on the spray characteristics was investigated. The influence of the mixing chamber height HS to diameter DS ratio and the volumetric flow rates of liquid and gas on the discharge coefficient values, spray angle, droplet size expressed by Sauter mean diameter D32, volumetric and radial distributions of droplet diameters in the spray stream were determined. The analysis of results showed that the discharge coefficient values depend on the Reynolds number for liquid and gas and the atomizer geometry. The spray angle increases as the flow rate of liquid and gas increases depending on the applied atomizer construction. The Sauter mean diameter value is correlated with the geometric dimensions of the atomizer swirl chamber. The rapid increase in D32 occurs after exceeding the value HS/DS ≈ 3. The Sauter mean diameter also depends on the operating parameters. A central area of stream is filled with smaller sized droplets as the gas flow rate increases.

Two-Phase Flow Patterns and Pressure Drop Inside a Vertical Pipe Containing a Short Helical Tape Insert

2014 ◽  
Author(s):  
Wen Liu ◽  
Bofeng Bai
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Swirling Flow ◽  
Large Diameter ◽  
Experimental Studies ◽  
Flow Patterns ◽  
Swirl Flow ◽  
Phase Flow ◽  
Vertical Pipe ◽  
Two Phase

Swirling gas-liquid two-phase flow patterns and pressure drop in vertical pipes of a large diameter are widely present in practical applications but not well documented in experimental studies. This paper presented an experimental study on gas-liquid two phase flow patterns and pressure drop inside a vertical pipe of 62mm in inner diameter (ID) containing a helical tape insert. Experimental results were obtained in a vertical visualization test section with a length of 7m, liquid mass velocities ranging from 0.3 to 1000 kg/(m2·s), and gas mass velocities from 3.2 to 900kg/(m2·s). Considering the decay of the swirl flow, the swirling flow regime map at different cross sections (z/D = 16, 32 and 64) were concluded, and their effects on the pressure drop were investigated.

Numeric Simulation of Gas-Dynamic Processes in the Swirl Combustion Chamber in STAR-CCM+

2012 ◽  
Vol 241-244 ◽  
pp. 1271-1277
Author(s):  
Igor Kuksov ◽  
Sergey Mochalov ◽  
Vladimir Sarychev
Keyword(s):  
Gas Flow ◽  
Dynamic Processes ◽  
Cylinder Surface ◽  
Stationary Mode ◽  
Surface Zone ◽  
Two Phase ◽  
Swirl Chamber ◽  
Gas Dynamic ◽  
Swirl Combustion ◽  
Numeric Simulation

The paper examines the theoretical and practical aspects of modeling of gas-dynamic processes in the swirl chamber. The results of numerical computation of a swirling gas flow induced by two-row header in cylindrical chamber are presented. The description of two-phase flow model subject to the injection of particles is given. It is revealed that in stationary mode two characteristic zones are formed: axial zone of quasi-solid rotation and cylinder surface zone.

scholarly journals Experimental and CFD modelling of a Progressive Cavity Pump using overset unstructured mesh

2021 ◽  
Vol 321 ◽  
pp. 02014
Author(s):  
Deisy Becerra ◽  
Miguel Asuaje ◽  
Alexander Zambrano ◽  
Nicolás Ratkovich
Keyword(s):  
Gas Flow ◽  
High Efficiency ◽  
High Viscosity ◽  
Computational Domain ◽  
Cfd Model ◽  
Operational Parameters ◽  
Cfd Modelling ◽  
Two Phase ◽  
Artificial Lift ◽  
Phase Liquid

A Progressive Cavity Pump (PCP) is widely used in industry as an artificial lift method because of its high efficiency during the pumping of high viscosity fluids and two-phase liquid-gas flow slurries. However, modelling PCP through Computational Fluid Dynamics (CFD) is quite complicated since it requires a meshing algorithm and is computationally expensive. Therefore, this study's main objective is to develop a CFD model capable of predicting a progressive cavity pump's behavior by implementing the Overset Mesh, which includes the relative motion between the rotor and the stator. Overset meshes are used to discretize a computational domain with several different meshes that arbitrarily overlap each other. They are most useful because the rotor geometry can be enclosed in a fluid (background) region and set to different positions. The PCP analyzed in this study is a GRP 4.0-4000 208 TSL 1-2 mono-lobe, which contains an API J55 stainless steel rotor and stator handling four Newtonian fluids (water, oil API 11, oil API 22, and oil API 31) at three rotational speeds (100 rpm, 150 rpm, and 200 rpm). The experimental data presented in this paper was collected in the PCP experimental facility of the SLACOL BCP Group (Tenjo, Colombia). All the measurements were made using the CILA2S controller for artificial lifting in the underground and on the surface to determine the operational curves of flowrate, volumetric efficiency, torque, and power consumed. The CFD model implementation was developed on Star- CCM+ version 15.02-R8 of 2020 for laminar and turbulent regimens. The results obtained through this study show that it is unnecessary to program a structured mesh to capture a progressive cavity pump's performance since the operational parameters evaluated to have an accuracy of 10% concerning the experimental data.Similarly, capturing the viscous effect near the wall and the transversal y horizontal slip inside the cavities is possible. The flow rate obtained for higher viscosity oils is more significant for the same pressure differences for water with average volumetric efficiencies of 85%. Finally, the pressure increase per stage is homogeneous along the pump's entire length for all fluids evaluated

The influence of the Stokes and Archimedes forces on the stability of a two-phase flow

2003 ◽  
Vol 3 ◽  
pp. 266-270
Author(s):  
B.H. Khudjuyerov ◽  
I.A. Chuliev
Keyword(s):  
Spectral Method ◽  
Stability Region ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Stability Characteristic ◽  
Phase Flow ◽  
Two Phase ◽  
The Stability

The problem of the stability of a two-phase flow is considered. The solution of the stability equations is performed by the spectral method using polynomials of Chebyshev. A decrease in the stability region gas flow with the addition of particles of the solid phase. The analysis influence on the stability characteristic of Stokes and Archimedes forces.

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