The Impact of the PDA Measurement Method in Forward Scatter on The Concentration of Gas-Particle Two Phase Flow

2007 ◽  
Author(s):  
Lizhe Chen ◽  
Zhichao Chen ◽  
Shaozeng Sun ◽  
Zhengqi Li
Keyword(s):  
Measurement Method ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Forward Scatter ◽  
Pda Measurement ◽  
The Impact

Solid–liquid two-phase flow and erosion calculation of butterfly valves at small opening based on DEM method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Benliang Xu ◽  
Zuchao Zhu ◽  
Zhe Lin ◽  
Dongrui Wang
Keyword(s):  
Peer Review ◽  
Two Phase Flow ◽  
Solid Particles ◽  
Phase Flow ◽  
Butterfly Valve ◽  
Two Phase ◽  
Content Type ◽  
Small Opening ◽  
Solid Liquid ◽  
The Impact

Purpose The study aims to decrease the effect of solid particles on a butterfly valve, which will cause seal failure and leakage, providing a reference for anti-wear design. Design/methodology/approach In this paper, computational fluid dynamics discrete element method (CFD-DEM) simulation was conducted to study the solid–liquid two-phase flow characteristics and erosion characteristics of a butterfly valve with a different opening. Findings Abrasion at 10% opening is affected by high-speed jets in upper and lower parts of the pipeline, where the erosion is intense. The impact of the jet on the upper part of 20% opening begins to weaken. With the top backflow vortex disappearing, the effect of lower jet is enhanced. Meanwhile, the bottom backflow vortex phenomenon is obvious, and the abrasion position moves downward. At 30% opening, the velocity is further weakened, and the circulation effect of lower flow channel is more obvious than that of the upper one. Originality/value It is the first time to use DEM to investigate the two-phase flow and erosion characteristics at a small opening of a butterfly valve, considering the effect of inter-particle collision. Therefore, this study carries on the thorough analysis and discussion. At the same opening degree, with increasing of the particle size, the abrasion of valve frontal surface increases when the size is less than 150 µm and decreases when it is greater than 150 µm. For the valve backflow surface, this boundary value becomes 200 µm. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0264/

Numerical and experimental investigation on the effect of the two-phase flow pattern on heat transfer of piston cooling gallery

2019 ◽  
Vol 20 (5) ◽  
pp. 507 ◽  
Author(s):  
Lijun Deng ◽  
Jian Zhang ◽  
Guannan Hao ◽  
Jing Liu
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Unstable Wave ◽  
Fluid Viscosity ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Process ◽  
The Impact ◽  
Piston Cooling

To study factors affecting the formation and conversion of two-phase flow pattern as well as the heat transfer of piston cooling gallery, a transient visual target test bench was set up to research the oscillatory flow characteristics in the cooling gallery under idle condition of the engine. The computational fluid dynamics (CFD) was employed while dynamic mesh technology, SST k–ω turbulence model and volume of fluid (VOF) two-phase flow model were applied to simulate the flow process of piston cooling gallery so as to predict the distribution pattern of two-phase flow. Simulation results were in good agreement with that experimentally obtained. It was observed that in the reciprocating movement of the piston, the action of two-phase flow oscillation was severe, forming some unstable wave flows and slug flows. Results show that under the same pipe diameter, the increase of fluid viscosity results in the decrease of amplitude and the increase of the liquid slugs number as well as the enhancement on heat transfer effect. In addition, it was revealed that injection pressure has little effect on the two-phase flow pattern. However, when the pressure is reduced, the change of the liquid phase is weakened and the locations of flow pattern transition move towards to the behind, thus the impact on the heat transfer is also faint.

The Impact of Surface Tension on the Oil-Water Stratified Flow

2011 ◽  
Vol 383-390 ◽  
pp. 826-829 ◽  
Author(s):  
Dao Zhen Xu ◽  
Guo Zhong Zhang ◽  
Xin Zhang
Keyword(s):  
Surface Tension ◽  
Two Phase Flow ◽  
Large Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Diameter Pipe ◽  
Small Density ◽  
Oil Water ◽  
The Impact

The stratified water-oil two—phase flow was modeled using VOF method in horizontal pipe and surface tension was taken into consideration using CSF model. It was found that the surface tension had great impact on the small density difference two-phase flow even in large diameter pipe, which would lead the interface curved and pressure gradient increased.

scholarly journals Numerical Simulation of Gas-Particle Two-Phase Flow in a Nozzle with DG Method

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Duan Maochang ◽  
Yu Xijun ◽  
Chen Dawei ◽  
Qing Fang ◽  
Zou Shijun
Keyword(s):  
Flow Field ◽  
Gas Phase ◽  
Mass Fraction ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Governing Equations ◽  
Two Phase ◽  
Dg Method ◽  
The Impact

In this paper, the discontinuous Galerkin (DG) method is applied to solve the governing equations of the dispersed two-phase flow with the two-fluid Euler/Euler approach. The resulting governing equations are simple in form and the solution process is very natural. The characteristics of the gas-particle two-phase flow in an engine nozzle are mainly analyzed, and the impacts of the particle mass fraction and particle size on the flow field and engine performance are evaluated. Because of the addition of particles, the gas flow field undergoes significant modifications. Increase in the mass fraction leads to a significant thrust loss in the gas phase, and the impact of the particles on the gas phase could be substantial. Therefore, a quantitative study of thrust loss in the nozzle due to the particle impact is made. It is found that the gas thrust in the two-phase flow is reduced, but the total thrust of the two-phase flow increases to a certain extent.

scholarly journals A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels

Sensors ◽  
2016 ◽  
Vol 16 (2) ◽  
pp. 159 ◽  
Author(s):  
Huajun Li ◽  
Haifeng Ji ◽  
Zhiyao Huang ◽  
Baoliang Wang ◽  
Haiqing Li ◽  
...  
Keyword(s):  
Void Fraction ◽  
Measurement Method ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Small Channels ◽  
Fraction Measurement

Numerical Simulation of Two-Phase Flow in Severely Damaged Core Geometries

2006 ◽  
Author(s):  
Phongsan Meekunnasombat ◽  
Florian Fichot ◽  
Michel Quintard
Keyword(s):  
Numerical Simulation ◽  
Porous Medium ◽  
Two Phase Flow ◽  
Immiscible Fluids ◽  
Macroscopic Model ◽  
Phase Flow ◽  
Two Phase ◽  
Fuel Rods ◽  
The Core ◽  
The Impact

In the event of a severe accident in a nuclear reactor, the oxidation, dissolution and collapse of fuel rods is likely to change dramatically the geometry of the core. A large part of the core would be damaged and would look like porous medium made of randomly distributed pellet fragments, broken claddings and relocated melts. Such a complex medium must be cooled in order to stop the accident progression. IRSN investigates the effectiveness of the water re-flooding mechanism in cooling this medium where complex two-phase flows are likely to exist. A macroscopic model for the prediction of the cooling sequence was developed for the ICARE/CATHARE code (IRSN mechanistic code for severe accidents). It still needs to be improved and assessed. It appears that a better understanding of the flow at the pore scale is necessary. As a result, a direct numerical simulation (DNS) code was developed to investigate the local features of a two-phase flow in complex geometries. In this paper, the Cahn-Hilliard model is used to simulate flows of two immiscible fluids in geometries representing a damaged core. These geometries are synthesized from experimental tomography images (PHEBUS-FP project) in order to study the effects of each degradation feature, such as displacement and fragmentation of the fuel rods and claddings, on the two-phase flow. For example, the presence of fragmented fuel claddings is likely to enhance the trapping of the residual phase (either steam or water) within the medium which leads to less flow fluctuations in the other phase. Such features are clearly shown by DNS calculations. From a series of calculations where the geometry of the porous medium is changed, conclusions are drawn for the impact of rods damage level on the characteristics of two-phase flow in the core.

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