Experimental Investigation on Air-Solid Two-Phase Mixture Discharge under AC Voltage

2011 ◽  
Vol 383-390 ◽  
pp. 4955-4961
Author(s):  
Wen Jun Yao ◽  
Zheng Hao He ◽  
He Ming Deng
Keyword(s):  
Gas Flow ◽  
Volume Fraction ◽  
Fundamental Problem ◽  
Solid Particles ◽  
Two Phase ◽  
The Common ◽  
Phase Mixture ◽  
Multi Phase ◽  
Inception Voltage ◽  
Statistical Rule

Multi-phase mixture (MPM) discharge has the common characteristics of randomness with air but more complex. How about the statistical rule of MPM discharge ? This is not only a fundamental problem for discharge research, but it has its own strong applied and practical characteristics. The air-solid two-phase mixtures(ASTPM) are employed to study and carry out some experiments for investigating the development and breakdown of MPM discharge under AC voltage. The results from experimental data show that the AC breakdown voltage and corona-inception voltage will drop when the solid particles are added to the discharge chamber with different permittivity and volume fraction. And there is no influence in gas flow and the corona current.

Tracking the Rheological Behavior Change of a Fresh Granular-Cement Paste Material to a Granular Material Based on DEM

2012 ◽  
Vol 446-449 ◽  
pp. 3803-3809
Author(s):  
Hooman Hoornahad ◽  
Eduard A. B. Koenders
Keyword(s):  
Numerical Simulation ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Analytical Techniques ◽  
Fluid Models ◽  
Continuum Approach ◽  
Two Phase ◽  
The Common ◽  
Phase Models ◽  
Multi Phase

The common approach to describe the rheological behavior of a granular-paste material relies on a description of the motion within the frame of continuum mechanics. However, since a granular-paste system cannot be considered as a homogeneous continuous fluid its behavior should not be estimated by common fluid models, such as Bingham or Herschell Bulkley models. Therefore, a continuum approach is not considered the best option to study the phase effects of a multi-phase material and its corresponding rheological behavior. In this particular case analytical techniques based on the multi-phase models are required. A more appropriate approach is to consider a granular-paste material as a two phase model that accounts for the effect of the gradually decreasing the volume fraction of the pasty phase until getting to zero value on the rheological behavior of the material. In this investigation, a cone test is used to evaluate the rheological behavior of a granular mix where a discrete element method (DEM) is considered as a basis of the numerical simulation.

EQUILIBRIUM VELOCITY DISTRIBUTION FUNCTIONS FOR A KINETIC MODEL OF TWO-PHASE FLOWS

1995 ◽  
Vol 05 (02) ◽  
pp. 191-211 ◽  
Author(s):  
LIONEL SAINSAULIEU
Keyword(s):  
Velocity Distribution ◽  
Gas Flow ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Velocity Distribution Function ◽  
Distribution Functions ◽  
Solid Particles ◽  
Navier Stokes ◽  
Two Phase ◽  
Entropy Balance

We consider a cloud of solid particles in a gas flow. The cloud is described by a probability density function which satisfies a kinetic equation. The gas flow is modeled by Navier-Stokes equations. The two phases exchange momentum and energy. We obtain the entropy balance of the gas flow and deduce some bounds for the volume fraction of the gas phase. Writing the entropy balance for the dispersed phase enables one to determine the particles equilibrium velocity distribution function when the gas flow is known.

Interaction of Shock and Expansion Wave With Solid Particles in Supersonic Flows

2002 ◽  
Author(s):  
Ali Dolatabadi ◽  
Javad Mostaghimi ◽  
Valerian Pershin
Keyword(s):  
Mach Number ◽  
Flow Regime ◽  
Drag Force ◽  
Gas Flow ◽  
Volume Fraction ◽  
Supersonic Flows ◽  
Operating Conditions ◽  
Solid Particles ◽  
Process Efficiency ◽  
Two Phase

Interaction of solid particles with shock and expansions in supersonic flows is analyzed. In this analysis, a dense cloud of solid particulates is modeled by using a fully Eulerian approach. The dispersed flow and the gas flow were considered in the Eulerian frame whereby most of the physical aspects of the gas-particle flow can be incorporated. In addition to the momentum and energy exchanges in the form of source terms appearing in the governing equations, the two phases were strongly coupled by considering the volume fraction of the particulate phase in the equations. The simulation performed for a High Velocity Oxy-Fuel (HVOF) process under typical operating conditions in which the powder loading is high and the two-phase flow is not dilute near the injection port. The simulations showed large variations in the flow regime in the region that most of the particles exist. Unlike the results corresponding to the Lagrangian approach, the flow becomes subsonic near the centerline and the drag force decreases significantly since the relative Mach number is small. The validation experiments showed that the variation of flow regime by changing the relative Mach number could significantly change the particle drag force, and consequently process efficiency.

scholarly journals Gas holdup in a reciprocating plate bioreactor: Non-Newtonian - liquid phase

2002 ◽  
Vol 56 (5) ◽  
pp. 198-203 ◽  
Author(s):  
Olivera Naseva ◽  
Ivica Stamenkovic ◽  
Ivana Bankovic-Ilic ◽  
Miodrag Lazic ◽  
Vlada Veljkovic ◽  
...  
Keyword(s):  
Gas Flow ◽  
Volume Fraction ◽  
Methyl Cellulose ◽  
Gas Holdup ◽  
Degree Of Polymerization ◽  
Operating Conditions ◽  
Solid Particles ◽  
Flow Index ◽  
Two Phase ◽  
Vibration Rate

The gas holdup was studied in non-newtonian liquids in a gas-liquid and gas-liquid-solid reciprocating plate bioreactor. Aqueous solutions of carboxy methyl cellulose (CMC; Lucel, Lucane, Yugoslavia) of different degrees of polymerization (PP 200 and PP 1000) and concentration (0,5 and 1%), polypropylene spheres (diameter 8.3 mm; fraction of spheres: 3.8 and 6.6% by volume) and air were used as the liquid, solid and gas phase. The gas holdup was found to be dependent on the vibration rate, the superficial gas velocity, volume fraction of solid particles and Theological properties of the liquid ohase. Both in the gas-liquid and gas-liquid-solid systems studied, the gas holdup increased with increasing vibration rate and gas flow rate. The gas holdup was higher in three-phase systems than in two-phase ones under otter operating conditions being the same. Generally the gas holdup increased with increasing the volume fraction of solid particles, due to the dispersion action of the solid particles, and decreased with increasing non-Newtonian behaviour (decreasing flow index) i.e. with increasing degree of polymerization and solution concentration of CMC applied, as a result of gas bubble coalescence.

Vortex Simulation for Behavior of Solid Particles Falling in Air

2011 ◽  
Author(s):  
Hisanori Yagami ◽  
Tomomi Uchiyama
Keyword(s):  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Air Flow ◽  
Three Dimensional ◽  
Particle Diameter ◽  
Vortex Method ◽  
Solid Particles ◽  
Particle Volume ◽  
Two Phase ◽  
Spherical Region

The behavior of small solid particles falling in an unbounded air is simulated. The particles, initially arranged within a spherical region in a quiescent air, are made to fall, and their fall induces the air flow around them, resulting in the gas-particle two-phase flow. The particle diameter and density are 1 mm and 7.7 kg/m3 respectively. A three-dimensional vortex method proposed by one of the authors is applied. The simulation demonstrates that the particles are accelerated by the induced downward air flow just after the commencement of their fall. It also highlights that the particles are whirled up by a vortex ring produced around the downward air flow after the acceleration. The effect of the particle volume fraction at the commencement of the fall is also explored.

scholarly journals Computational investigation of liquid-solid slurry flow through an expansion in a rectangular duct

2014 ◽  
Vol 62 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Volume Fraction ◽  
Particle Density ◽  
Fluid Model ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Rectangular Duct ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Two Fluid Model ◽  
Two Fluid

Abstract The flow of a mixture of liquid and solid particles at medium and high volume fraction through an expansion in a rectangular duct is considered. In order to improve the modelling of the phenomenon with respect to a previous investigation (Messa and Malavasi, 2013), use is made of a two-fluid model specifically derived for dense flows that we developed and implemented in the PHOENICS code via user-defined subroutines. Due to the lack of experimental data, the two-fluid model was validated in the horizontal pipe case, reporting good agreement with measurements from different authors for fully-suspended flows. A 3D system is simulated in order to account for the effect of side walls. A wider range of the parameters characterizing the mixture (particle size, particle density, and delivered solid volume fraction) is considered. A parametric analysis is performed to investigate the role played by the key physical mechanisms on the development of the two-phase flow for different compositions of the mixture. The main focuses are the distribution of the particles in the system and the pressure recovery

A HIERARCHICAL MODEL FOR MULTI-PHASE FRACTAL MEDIA

Fractals ◽  
2010 ◽  
Vol 18 (01) ◽  
pp. 53-64 ◽  
Author(s):  
MAOFEI MEI ◽  
BOMING YU ◽  
JIANCHAO CAI ◽  
LIANG LUO
Keyword(s):  
Distribution Function ◽  
Pore Space ◽  
Fractal Dimensions ◽  
Solid Particles ◽  
Two Phase ◽  
Fractal Media ◽  
Proposed Model ◽  
Three Phase ◽  
Multi Phase ◽  
Good Agreement

The size distributions of solid particles and pores in porous media are approximately hierarchical and statistically fractals. In this paper, a model for single-phase fractal media is constructed, and the analytical expressions for area, fractal dimension and distribution function for solid particles are derived. The distribution function of solid particles obtained from the proposed model is in good agreement with available experimental data. Then, a model for approximate two-phase fractal media is developed. Good agreement is found between the predicted fractal dimensions for pore space from the two-phase fractal medium model and the existing measured data. A model for approximate three-phase fractal media is also presented by extending the obtained two-phase model.

Studies of Vibration-Induced Multi-Phase Fluid Phenomena and Pulsating Heat Pipe Performance Under Microgravity

2003 ◽  
Author(s):  
Masahiro Kawaji
Keyword(s):  
Space Shuttle ◽  
Space Station ◽  
Heat Pipes ◽  
Solid Particles ◽  
Protein Crystals ◽  
Microgravity Environment ◽  
Pulsating Heat Pipe ◽  
Two Phase ◽  
Theoretical Investigations ◽  
Multi Phase

High quality semi-conductor and protein crystals can be grown in space by utilizing the microgravity environment in which natural convection and sedimentation effects are suppressed. But some vibrations exist on space platforms such as Space Shuttle and International Space Station that can induce crystal and fluid motions, affecting the quality of the crystals grown in space. Since the effects of small vibrations (called g-jitter) on crystal growth are not yet precisely known in space, experimental and theoretical investigations are being conducted to better understand the vibration effects on the motion of protein crystals and solid particles in liquid-filled cells. Another topic under investigation is the operation of pulsating heat pipes under microgravity. A recent experiment performed on a parabolic airplane has shown the positive effect of reduced gravity on the pulsating motion of vapour-liquid two-phase flow and heat transport in pulsating heat pipes.

A Test Study of 50% Lightning Impulse Breakdown Voltage on Rod-Plane Gap with Two-Phase Mixture of Gas and Solid Particles

2007 ◽  
Vol 9 (6) ◽  
pp. 695-697 ◽  
Author(s):  
He Zhenghao ◽  
Xu Huaili ◽  
Bai Jing ◽  
Yu Fusheng ◽  
Hu Feng ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Solid Particles ◽  
Two Phase ◽  
Test Study ◽  
Lightning Impulse ◽  
Phase Mixture

Three-Dimensional Numerical Simulation of Convective Melting of Solid Particles in a Fluid

1999 ◽  
Author(s):  
Y. L. Hao ◽  
Y.-X. Tao
Keyword(s):  
Volume Fraction ◽  
Solid Phase ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Phase Changes ◽  
Solid Particles ◽  
Preliminary Calculation ◽  
Two Phase ◽  
Closed Set ◽  
Gravity Effects

Abstract A physical model of two-phase flow and heat-mass transfer with the phase changes based on the theory of interacting continua is proposed. All terms in the conservation equations are analyzed and the constitutive equations are presented. A closed set of governing equations describing the convective melting of solid particles in a fluid is obtained. The numerical method is developed for the solution of velocity, temperature, and volume fraction of solid phase for the three-dimensional melting in a rectangular cross-section channel. Preliminary calculation, including gravity effects, shows that the result is reasonable. This study provides a basis for the theoretical and experimental investigation of convective melting of solid particles in a fluid.

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