Numerical Simulation of the Two-Phase Flow in Novel Combined Top and Corner Spray Degassing Tank for Aluminum Melt

2012 ◽  
Vol 510 ◽  
pp. 790-794
Author(s):  
Hui Sun ◽  
Zhi Yong Zhou
Keyword(s):  
Two Phase Flow ◽  
Volume Fraction ◽  
Fluid Model ◽  
Flow Behavior ◽  
Phase Flow ◽  
Gas Velocity ◽  
Two Phase ◽  
Aluminum Melt ◽  
Two Fluid Model ◽  
Gas Liquid Flow

The Eulerian two-fluid model incorporated with the multiple reference frame approach is adopted to predict the gas-liquid two-phase flow in the novel combined top and corner spray degassing tank for aluminum melt. The influence of different parameters, such as gas velocity or hole areas at the tank corners on the gas-liquid flow behavior is also investigated. Results show that little gas emerges near the wall of tank equipped with traditional rotating spray degasser. Using the combined top and corner spray degasser, the distribution of bubbles in the tank, especially near the tank wall, is improved significantly, which advantages the hydrogen removal. With the increasing gas velocity or hole areas at the tank corners, the width of ring zone with low gas volume fraction decreases, and thus enhances the effect of hydrogen removal.

scholarly journals Natural modes of the two-fluid model of two-phase flow

2021 ◽  
Vol 33 (3) ◽  
pp. 033324
Author(s):  
Alejandro Clausse ◽  
Martín López de Bertodano
Keyword(s):  
Two Phase Flow ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Phase ◽  
Natural Modes ◽  
Two Fluid Model ◽  
Two Fluid

A Physically Based, One-Dimensional Two-Fluid Model for Direct Contact Condensation of Steam Jets Submerged in Subcooled Water

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
David Heinze ◽  
Thomas Schulenberg ◽  
Lars Behnke
Keyword(s):  
Direct Contact ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional ◽  
Two Fluid Model ◽  
Contact Condensation ◽  
Two Fluid

A simulation model for the direct contact condensation of steam in subcooled water is presented that allows determination of major parameters of the process, such as the jet penetration length. Entrainment of water by the steam jet is modeled based on the Kelvin–Helmholtz and Rayleigh–Taylor instability theories. Primary atomization due to acceleration of interfacial waves and secondary atomization due to aerodynamic forces account for the initial size of entrained droplets. The resulting steam-water two-phase flow is simulated based on a one-dimensional two-fluid model. An interfacial area transport equation is used to track changes of the interfacial area density due to droplet entrainment and steam condensation. Interfacial heat and mass transfer rates during condensation are calculated using the two-resistance model. The resulting two-phase flow equations constitute a system of ordinary differential equations, which is solved by means of the explicit Runge–Kutta–Fehlberg algorithm. The simulation results are in good qualitative agreement with published experimental data over a wide range of pool temperatures and mass flow rates.

Eulerian Two-Phase Flow Modeling of Steam Direct Contact Condensation for the Fukushima Accident Investigation

2014 ◽  
Author(s):  
Marco Pellegrini ◽  
Giulia Agostinelli ◽  
Hidetoshi Okada ◽  
Masanori Naitoh
Keyword(s):  
Two Phase Flow ◽  
Volume Fraction ◽  
Fluid Model ◽  
Fluid Dynamic ◽  
Interfacial Region ◽  
Phase Flow ◽  
Two Phase ◽  
Fukushima Accident ◽  
Average Cell Size ◽  
Average Cell

Steam condensation is characterized by a relatively large interfacial region between gas and liquid which, in computational fluid dynamic (CFD) analyses, allows the creation of a discretized domain whose average cell size is larger than the interface itself. For this reason generally one fluid model with interface tracking (e.g. volume of fluid method, VOF) is employed for its solution in CFD, since the solution of the interface requires a reasonable amount of cells, reducing the modeling efforts. However, for some particular condensation applications, requiring the computation of long transients or the steam ejected through a large number of holes, one-fluid model becomes computationally too expensive for providing engineering information, and a two-fluid model (i.e. Eulerian two-phase flow) is preferable. Eulerian two-phase flow requires the introduction of closure terms representing the interactions between the two fluids in particular, in the condensation case, drag and heat transfer. Both terms involve the description of the interaction area whose definition is different from the typical one adopted in the boiling analyses. In the present work a simple but effective formulation for the interaction area is given based on the volume fraction gradient and then applied to a validation test case of steam bubbling in various subcooling conditions. It has been shown that this method gives realistic values of bubble detachment time, bubble penetration for the cases of interest in the nuclear application and in the particular application to the Fukushima Daiichi accident.

scholarly journals Numerical analysis of pressure fluctuation in a multiphase rotodynamic pump with air–water two-phase flow

2019 ◽  
Vol 74 ◽  
pp. 18 ◽  
Author(s):  
Wenwu Zhang ◽  
Zhiyi Yu ◽  
Yongjiang Li ◽  
Jianxin Yang ◽  
Qing Ye
Keyword(s):  
Pressure Fluctuation ◽  
Two Phase Flow ◽  
Guide Vane ◽  
Fluid Model ◽  
Pure Water ◽  
Maximum Amplitude ◽  
Phase Flow ◽  
Two Phase ◽  
Rotor Stator Interaction ◽  
Two Fluid Model

Pressure fluctuation in single-phase pumps has been studied widely, while less attention has been paid to research on multiphase pumps that are commonly used in the petroleum chemical industry. Therefore, this study investigates the pressure fluctuation for a multiphase rotodynamic pump handling air–water two-phase flow. Simulations based on the Euler two-fluid model were carried out using ANSYS_CFX16.0 at different Inlet Gas Void Fractions (IGVFs) and various flow rate values. Under conditions of IGVF = 0% (pure water) and IGVF = 15%, the accuracy of the numerical method was tested by comparing the experimental data. The results showed that the rotor–stator interaction was still the main generation driver of pressure fluctuation in gas–liquid two-phase pumps. However, the fluctuation near the impeller outlet ascribe to the rotor–stator interaction was weakened by the complex gas–liquid flow. For the different IGVF, the variation trend of fluctuation was similar along the streamwise direction. That is, the fluctuation in the impeller increased before decreasing, while in the guide vane it decreased gradually. Also, the fluctuation in the guide vane was generally greater than for the impeller and the maximum amplitude appeared in the vicinity of guide vane inlet.

scholarly journals CFD Simulation of Polydispersed Bubbly Two-Phase Flow around an Obstacle

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
E. Krepper ◽  
P. Ruyer ◽  
M. Beyer ◽  
D. Lucas ◽  
H.-M. Prasser ◽  
...  
Keyword(s):  
Size Distribution ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Size Distribution Function ◽  
Phase Flow ◽  
Two Phase ◽  
Ansys Cfx ◽  
Two Fluid Model ◽  
Drag And Lift

This paper concerns the model of a polydispersed bubble population in the frame of an ensemble averaged two-phase flow formulation. The ability of the moment density approach to represent bubble population size distribution within a multi-dimensional CFD code based on the two-fluid model is studied. Two different methods describing the polydispersion are presented: (i) a moment density method, developed at IRSN, to model the bubble size distribution function and (ii) a population balance method considering several different velocity fields of the gaseous phase. The first method is implemented in the Neptune_CFD code, whereas the second method is implemented in the CFD code ANSYS/CFX. Both methods consider coalescence and breakup phenomena and momentum interphase transfers related to drag and lift forces. Air-water bubbly flows in a vertical pipe with obstacle of the TOPFLOW experiments series performed at FZD are then used as simulations test cases. The numerical results, obtained with Neptune_CFD and with ANSYS/CFX, allow attesting the validity of the approaches. Perspectives concerning the improvement of the models, their validation, as well as the extension of their applicability range are discussed.

A NUMERICAL STUDY OF TWO-PHASE FLOW USING A TWO-DIMENSIONAL TWO-FLUID MODEL

2004 ◽  
Vol 45 (10) ◽  
pp. 1049-1066 ◽  
Author(s):  
Moon-Sun Chung ◽  
Seung-Kyung Pak ◽  
Keun-Shik Chang
Keyword(s):  
Two Phase Flow ◽  
Numerical Study ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Two Fluid Model ◽  
Two Fluid

Numerical Simulation of the Two-Phase Flow in Centrifugal Pump Impellers

2002 ◽  
Author(s):  
Rudolf Schilling ◽  
Moritz Frobenius
Keyword(s):  
Centrifugal Pump ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Fluid Model ◽  
Numerical Procedure ◽  
Phase Flow ◽  
Two Phase ◽  
Simulation Tools ◽  
Total Wear ◽  
Small Volume Fraction

The numerical simulations of three types of two-phase flow in centrifugal pump impellers are described. First, the liquid-solid particle flow is modeled by an Euler-Lagrangeian approach assuming a mass concentration less than 5% and particle diameters being less than 1000 microns. The empirical erosion model to predict the local and total wear is calibrated by measurements. Second, the influence of the relative air contents on the head-drop is simulated assuming a relatively small volume fraction and applying a simple one-fluid model. The mixture is characterized by a common density depending on the flow field. Finally, the cavitating flow is studied by implementing the Rayleigh equation into the numerical procedure describing the transient process of bubble growth and collapse. The developed simulation tools are applied to predict the three types of two-phase flows in impellers. Within the defined ranges of application the simulation results agree fairly well with the experimental data.

Sign in / Sign up

Export Citation Format

Share Document