scholarly journals Investigations of Gas–Particle Two-Phase Flow in Swirling Combustor by the Particle Stokes Numbers

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 951
Author(s):  
Yang Liu ◽  
Guohui Li
Keyword(s):  
Two Phase Flow ◽  
Particle Diameter ◽  
Tangential Direction ◽  
Stokes Number ◽  
Order Moment ◽  
Frictional Stress ◽  
Phase Flow ◽  
Two Phase ◽  
Close Relationship ◽  
Experimental Validations

Gas turbulence modulations and particle dispersions of swirling gas–particle two-phase flow in the combustor is investigated under the large spans of the particle Stokes numbers. To fully consider the preferential concentrations and anisotropic dispersions of a particle, a kinetic frictional stress model coupled with a second-order moment two-phase turbulent model and granular temperature equation is improved. The proposed modeling and simulations are in good agreement with the experimental validations. Results show turbulent modulations and particle dispersions exhibit strongly anisotropic characteristics, keeping a close relationship with flow structure. The axial gas velocity and RMS fluctuation velocity of 45.0-μm EGP was approximately 5.0 times and 3.0 times greater than 1000.0 μm Copper particles, and their axial particle velocity was 0.25 times and twice greater than those of 45.0 μm EGP. The degree of modulation in the axial–radial direction is larger than those of radial–tangential and axial–tangential direction. Particle dispersions are sensitive to particle diameter parameters and intensified by higher Stokes number.

Numerical Investigation of Gas-Solid Two Phase Flow Over Composite Structures of Elbow and Venturi Tube

2011 ◽  
Author(s):  
Zhangyang Kang ◽  
Mo Yang ◽  
Yuwen Zhang ◽  
Chunsun Guo
Keyword(s):  
Composite Structures ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Particle Diameter ◽  
Stokes Number ◽  
Pulverized Coal ◽  
Venturi Tube ◽  
Phase Flow ◽  
Detached Eddy Simulation ◽  
Two Phase

The Euler-Lagrange method and Dispersed Phase Model (DPM) are adopted in the numerical simulation of gas-solid two-phase flow inside elbow, venturi tube and a new rich-lean pulverized coal burner combined elbow and venturi tube. It is to study the characteristic of coal distribution and the outlet characteristics of rich/lean separation influenced by pulverized coal particle diameter and density. he Detached-eddy-simulation (DES) approach is involved in the calculation of turbulence dispersion of gas phase. The Discrete random walk model (DRW) is used in the turbulence of solid phase. The results show that, for the particles of smaller diameter (10μm), the effect of rich-lean separation of three types of structure is unobvious; for the particles of larger diameter (50μm), this new structure burner can achieve rich-lean separation and the maximum concentration rises as the Stokes number increases; for the particles of more larger diameter 100μm, with the increasing number of St, there will be more than one core of concentration.

scholarly journals Hydrodynamic Modeling of Turbulence Modulation by Particles in Swirling Gas-Particle Two-Phase Flow

2021 ◽  
Author(s):  
Yang Liu ◽  
Lixing Zhou
Keyword(s):  
Shear Stress ◽  
Two Phase Flow ◽  
Heavy Particle ◽  
Light Particle ◽  
Particle Collision ◽  
Order Moment ◽  
Enhancement Effect ◽  
Phase Flow ◽  
Primary Role ◽  
Two Phase

Abstract Turbulence modulations by particles of swirling gas-particle two-phase flow the axisymmetric chamber is investigated. To fully consider the preferential concentrations and anisotropic dispersions of particle, a second-order moment model coupling particle-particle collision model was improved based on the Eulerian-Eulerian two-fluid approach and the kinetic theory of granular flow. Proposed model, algorithm and in-house codes are validated and they are in good agreement with the experiment. Effects of ultralight expanded graphite and heavy Copper particles with large spans of Stokes number on gas velocity and fluctuations, Reynolds shear stress and tensor invariants, turbulence kinetic energy, and vortices structures are numerically simulated. Results show turbulent modulation exhibits strongly anisotropic characteristics and keeps in close relationship with flow structure. The disturbances of modulations, the alternations of vortex evolution are enforced by heavy-large particle with higher Stokes numbers. Preferential accumulations of light particle at shear stress regions in low vortices are weaker than those of heavy particle. For axial turbulence modulations, heavy particle plays the primary role on inhibition action due to larger inertia and light particle contributes to enhancement effect due to excellent followability.

Visualizing Test on the Distribution Rule of Coarse Particles in a Double Blade Pump

2019 ◽  
Author(s):  
Xianfang Wu ◽  
Xiao Tian ◽  
Minggao Tan ◽  
Houlin Liu
Keyword(s):  
Particle Concentration ◽  
Two Phase Flow ◽  
Particle Density ◽  
Particle Diameter ◽  
Phase Flow ◽  
Coarse Particles ◽  
Two Phase ◽  
Solid Liquid ◽  
Blade Pump ◽  
Flow Pump

Abstract As a typical fluid mechanics problem, pump blockage has always been a hot research topic. The obtaining of the distribution of coarse particles in the solid-liquid two-phase flow pump is the basis of improving its non-blocking performance. High-speed photography technique is applied to do visualizing test and research on the distribution of coarse particles in a double blade pump. The effects of particle concentration, particle density and particle diameter on the distribution of coarse particles in the solid-liquid two-phase flow pump at different phases are studied. Besides, the variation of hydraulic performance of the double blade pump under different parameters is also analyzed. The results show that the particles in the impeller mainly located in the vicinity of the blade pressure surface, and the distribution of the particles in each section of the volute is quite different. The great difference in particle density can result in obviously uneven distribution of particles. With the increase of particle diameter, particle density and particle concentration, the pump head and efficiency both decrease while the shaft power increase on the contrary. This research results can also provide a basis for the optimization design of solid-liquid two-phase flow pumps.

Research on Particle Characteristics of Cellulosine Used in Generation Basing on Two-Phase Flow of the Gas and Solid

2010 ◽  
Vol 431-432 ◽  
pp. 483-486
Author(s):  
Lan Yu Yang ◽  
Yan Ma
Keyword(s):  
Power Generation ◽  
Particle Size ◽  
Two Phase Flow ◽  
Influence Factors ◽  
Particle Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Particle Characteristics ◽  
Biomass Resources ◽  
Grading Model

The amount of remainder in wooden biomass resources available which was used for power generation in China was surveyed. Technique feasibility of the wooden remainder used in power generation was analyzed. A super fine cellulosine disintegrator for power generation was designed, which combined both characteristics of the wooden biomass and particle size of the cellulosine for power generation. The cellulosine particles which were obtained were put emphasis on analyzing and all kinds of stressed conditions were obtained during process of the grading under the environment for two-phase flow of the gas and solid. One kind of grading model of the cellulosine particles for power generation was established in view of all kinds of the influence factors comprehensively. One kind of calculation method for grading particle-diameter of the cellulosine particle, and the experiment results showed that this method was feasible.

Two-Order Moment Trajectory Model of Two-Phase Turbulence Flow Based on Particle PDF Transport Equation

2014 ◽  
Vol 668-669 ◽  
pp. 318-321 ◽  
Author(s):  
Jiang Rong Xu ◽  
Lu Wang
Keyword(s):  
Transport Equation ◽  
Two Phase Flow ◽  
Statistical Characteristics ◽  
Order Moment ◽  
Phase Flow ◽  
Two Phase ◽  
Trajectory Model ◽  
Turbulence Flow

Based on the PDF transport equation of particle, a two-order moment trajectory model of particles (TOMTM) is proposed to obtain reasonable statistical characteristics of a two-phase flow. Using the method proposed by Risken, It is shown that TOMTM is just the solution of the particles PDF equation

Numerical Simulation for a Backward-Facing Step Two-Phase Flow Using TOMTM

2014 ◽  
Vol 668-669 ◽  
pp. 314-317
Author(s):  
Jiang Rong Xu ◽  
Jin Fang Gao ◽  
Lu Wang
Keyword(s):  
Numerical Simulation ◽  
Transport Equation ◽  
Correlation Coefficient ◽  
Two Phase Flow ◽  
Order Moment ◽  
Phase Flow ◽  
Backward Facing Step ◽  
Two Phase ◽  
Trajectory Model ◽  
Anisotropic Turbulence

Based on the PDF transport equation of particle, Using both non-isotropic correlation coefficient and isotropic correlation coefficient, the two-order moment trajectory model of particles (TOMTM) is used to simulate the backward-facing step two-phase flow. It is shown that the isotropic correlation coefficient of TOMTM can simulate the anisotropic turbulence of particle better.

scholarly journals Modeling of soot particle collision and growth paths in gas-solid two-phase flow

2020 ◽  
pp. 215-215
Author(s):  
Hongling Ju ◽  
Fanquan Bian ◽  
Mingrui Wei
Keyword(s):  
Soot Particle ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Collision Frequency ◽  
Particle Growth ◽  
Stokes Number ◽  
Collision Probability ◽  
Particle Collision ◽  
Phase Flow ◽  
Two Phase

Particle collision is an important process in soot particle growth. In this research, based on gas-solid two-phase flow, particle trajectory was traced by the Lagrange approach with periodic boundaries. Trajectory intersection, collision probability, and critical velocity were considered, and the growth path of each particle was traced. The collision frequency (fc), agglomeration frequency (fa), and friction collision frequency (ffc) were calculated, and the main influence factors of particle collision were analyzed. The results showed that fc, fa, fa/fcincreased with the increase of the particle volume fraction and gasphasevelocity(v), but the particle initial diameter (dpi) andvhad the great influence on fa/fc. fa/fcobviously decreased with the increase of dpiand v.The statistical analysis of fa/fcand Stokes number showed that fa/fcdecreased with the increase of Stokes number, especially when stokes number was extremely small, fa/fcdecreased rapidly. Using the trajectory analysis of each particle, the particle growth process could be classified in three types: firstly, the particles that did not agglomerate with any particles during the entire calculation process; secondly, the particles that continually agglomerated with small particles to generate larger ones; and finally, the particles that were agglomerated by larger particles at some calculation moment.

scholarly journals Simulation of Abrasion Characteristics of Polar Ship Seawater Pipelines under the Coupling of Ice Particles and Vibration

2020 ◽  
Vol 10 (4) ◽  
pp. 1349
Author(s):  
Guan-Chen Liu ◽  
Li Xu ◽  
Jie Li ◽  
Qiang Sun ◽  
Zong-Qiang Liu ◽  
...  
Keyword(s):  
Wear Rate ◽  
Flow Velocity ◽  
Two Phase Flow ◽  
Particle Diameter ◽  
Phase Flow ◽  
Particle Rotation ◽  
Two Phase ◽  
General Law ◽  
Ice Particles ◽  
Static Conditions

Under the erosion of seawater–ice two-phase flow, seawater in pipelines of polar ships can cause the pipeline failures that threaten the safety of navigations. The discrete phase model (DPM) and erosion wear model (EWM) were established by using the computational fluid dynamics (CFD) method for numerical analysis of the 90° elbow with relatively severe erosion. This paper explores the erosion effect of pipelines under different conditions and puts forward optimal measures for pipeline protection. Compared with the existing multiphase flow research, the novelty of this study is that vibration conditions are considered and parameters such as two-phase flow velocity, ice packing factor (IPF), ice particle diameter and ice particle rotation characteristics are combined with vibration conditions. Combined with the comprehensive analysis of erosion effects of static pipelines, a general law of seawater pipeline wear under vibration is obtained. The results show that pipeline wear under vibration is more serious than under static conditions. Under static conditions, the wear of the same section in the pipeline increases with the increases of two-phase flow velocity and IPF. However, under vibration conditions, when the velocity is less than 3 m/s, the wear of the pipeline has no significant change, while when the velocity is over 3 m/s, the wear rate increases significantly. The particle diameter has little effect on the wear of static pipes, but under the vibration condition, the pipe wear rate decreases with the increase of particle diameter, and it starts to stabilize when the diameter exceeds 0.3 mm. If the rotation characteristics of ice particles are taken into account, the wear rate along the pipeline is significantly higher than that without particle rotation.

Numerical Research about Two-Phase Flow under Different Acceleration in SRM with Embedded Nozzle

2013 ◽  
Vol 365-366 ◽  
pp. 233-236
Author(s):  
Xiong Chen ◽  
Hai Feng Xue ◽  
Yong Luo
Keyword(s):  
Flow Field ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Particle Diameter ◽  
Phase Flow ◽  
Solid Rocket Motor ◽  
Two Phase ◽  
Axial Acceleration ◽  
The Difference ◽  
The Impact

The complex gas-solid two-phase flow in a full-sized solid rocket motor with embedded nozzle under different acceleration condition was simulated with Euler-Lagrange model. Influences of different particle diameters and acceleration conditions on particle trajectories were analyzed. Simulation results show that the difference between gas flow field and two-phase flow field is significant. The particle accumulation zone above inner wall of chamber and nozzle is mainly concentrated in two regions. The accretion of the particle diameter will cause the following property worse, and the particles can easily form a highly-concentrated aggregation flow. With the increasing of axial-acceleration, the impact point in line2 will move backward in rear head.

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