scholarly journals Analysis of Flow and Wear Characteristics of Solid–Liquid Two-Phase Flow in Rotating Flow Channel

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1512
Author(s):  
Peng Wang ◽  
Xinyu Zhu ◽  
Yi Li
Keyword(s):  
Wear Rate ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Discrete Phase Model ◽  
Rotating Disc ◽  
Two Phase ◽  
Wear Area ◽  
Severe Wear ◽  
Working Surface ◽  
Discrete Phase

To study the flow characteristics and the wear distribution of pumps at different rotation speeds, a rotating disc with three blades was designed for experiments. Numerical simulations were conducted using a computational fluid dynamics-discrete phase model (CFD–DPM) approach. The experimental and numerical results were compared, and the flow characteristics and wear behaviors were determined. As the speed increased, the particles at the blade working surface aggregated. The particle velocity gradually increased at the outlet of the channel. The severe wear areas were all located in the outlet area of the blade working surface, and the wear area extended toward the inlet area of the blade with increasing speed. The wear rate of the blade surface increased as the speed increased, and an area with a steady wear rate appeared at the outlet area of the blade. When the concentration was more than 8%, the severe wear areas were unchanged at the same speed. When the speed increased, the severe wear areas of the blade produced wear ripples, and the area of the ripples increased with increasing speed. The height difference between the ripples along the flow direction on the blade became larger as the speed increased.

Effect of Tube Diameter on Flow Phenomena of Gas-Liquid Two-Phase Flow in Microchannels

2015 ◽  
Author(s):  
Hideo Ide ◽  
Eiji Kinoshita ◽  
Ryo Kuroshima ◽  
Takeshi Ohtaka ◽  
Yuichi Shibata ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Water Solution ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Tube Diameter ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena ◽  
The Waves

Gas-liquid two-phase flows in minichannels and microchannels display a unique flow pattern called ring film flow, in which stable waves of relatively large amplitudes appear at seemingly regular intervals and propagate in the flow direction. In the present work, the velocity characteristics of gas slugs, ring films, and their features such as the gas slug length, flow phenomena and frictional pressure drop for nitrogen-distilled water and nitrogen-30 wt% ethanol water solution have been investigated experimentally. Four kinds of circular microchannels with diameters of 100 μm, 150 μm, 250 μm and 518 μm were used. The effects of tube diameter and physical properties, especially the surface tension and liquid viscosity, on the flow patterns, gas slug length and the two-phase frictional pressure drop have been investigated by using a high speed camera at 6,000 frames per second. The flow characteristics of gas slugs, liquid slugs and the waves of ring film are presented in this paper.

Numerical Simulation of Two-Phase Flow inside and outside a Swirl Nozzle for Dispersing Superfine Powder

2012 ◽  
Vol 505 ◽  
pp. 170-174
Author(s):  
Wei Dong Shi ◽  
Liang Zhang ◽  
Hai Yan He ◽  
Jiang Hai Liu ◽  
Liang Chen
Keyword(s):  
Total Pressure ◽  
Concentration Distribution ◽  
Gas Flow ◽  
Reynolds Stress Model ◽  
Phase Flow ◽  
Discrete Phase Model ◽  
Two Phase ◽  
Discrete Phase ◽  
Particle Group ◽  
Nozzle Structure

In this paper, a swirl nozzle is established to disperse superfine powder aerodynamically. And Reynolds stress model (RSM) is adopted to simulate the strongly swirling, compressible and transonic gas flow in the nozzle and its rear. Combined with discrete phase model (DPM), the concentration distribution of particle group in size of 2.5μm is studied. The simulated results show that, the distribution of swirl strength is determined basically by the nozzle structure, while the total pressure has little effect on it; compared with an irrotational nozzle, the swirl nozzle could achieve a better dispersing effect for superfine powder.

scholarly journals Prediction of Horizontal Pneumatic Conveying of Large Coal Particles Using Discrete Phase Model

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Daolong Yang ◽  
Ge Li ◽  
Yanxiang Wang ◽  
Qingkai Wang ◽  
Jianping Li ◽  
...  
Keyword(s):  
Simulation Method ◽  
Phase Model ◽  
Pneumatic Conveying ◽  
Discrete Phase Model ◽  
Two Phase ◽  
Coal Particles ◽  
Large Particles ◽  
Discrete Phase ◽  
Field Velocity ◽  
Conveying System

The pneumatic conveying focusing on gas-solid two-phase flow plays an important role in a conveying system. Previous work has been conducted in the fields of small particles, where the size was less than 5 mm; however, there are few studies regarding large sizes (>5 mm). In order to predict the horizontal pneumatic conveying of large coal particles, the coupling methods based on the Euler–Lagrange approach and discrete phase model (DPM) have been used for the simulated research. Compared with the experimental results under the same working condition, the particle trajectory obtained by simulation is similar to the particle distribution at the same position in the experiment, and it turns out that the simulation method is feasible for the horizontal pneumatic conveying of large particles. Multifactor simulations are also carried out to analyse the effects of particle size, flow field velocity, solid-gas rate, and pipe diameter on the wall abrasion during horizontal pneumatic conveying, which provides simulation reference and design guide for pneumatic conveying of large particles.

An Experimental Investigation of Gas-Liquid Heat Transfer in Rectangular Micro-Channels

2013 ◽  
Author(s):  
Sira Saisorn ◽  
Somchai Wongwises ◽  
Piyawat Kuaseng ◽  
Chompunut Nuibutr ◽  
Wattana Chanphan
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Camera System ◽  
Micro Channels ◽  
Flow Mechanisms

The investigations of heat transfer and fluid flow characteristics of non-boiling air-water flow in micro-channels are experimentally studied. The gas-liquid mixture from y-shape mixer is forced to flow in the 21 parallel rectangular microchannels with 40 mm long in the flow direction. Each channel has a width and a depth of 0.45 and 0.41 mm, respectively. Flow visualization is feasible by incorporating the stereozoom microscope into the camera system and different flow patterns are recorded. The experiments are performed under low superficial velocities. Two-phase heat transfer gives better results when compared with the single-phase flow. It is found from the experiment that heat transfer enhancement up to 53% is obtained over the single-phase flow. Also, the change in the configuration of the inlet plenum can result in the different two-phase flow mechanisms.

Study of the Effects of Shearer’ Kinematic Parameters on on-Way Distribution of Dust on Coal Face

2011 ◽  
Vol 127 ◽  
pp. 400-405
Author(s):  
Xiao Huo Li ◽  
Shu Ming Liu ◽  
Zhi Long Huang ◽  
Wei Du
Keyword(s):  
Rotational Speed ◽  
Dust Concentration ◽  
Discrete Phase Model ◽  
Kinematic Parameters ◽  
Coal Face ◽  
Two Phase ◽  
Concentration Maximum ◽  
Discrete Phase ◽  
And Migration ◽  
Kinematical Parameters

In order to research the effects of shearer’ kinematical parameters on on-way distribution of dust on coal face, according to the theory of suspension gas-solid two-phase flow and the theory of cutting dust formation, mathematical model of on-way dust concentration was established, methods of determining parameters were given, dust migration was simulated by using the discrete phase model (DPM) in FLUENT, on-way distribution regularity of dust was found. According to calculation of the quantity of cutting dust at different hauling speed and different rotational speed of drum, dust migration was simulated and migration regularity was showed as follows: dust concentration of every point on a coal face increased as hauling speed decreased or rotational speed increased. In addition, with rotational speed increased, the position of concentration maximum moved a little along downwind.

Visualization Study on Two-Phase Flow Behaviors in the Gas-Liquid-Solid Microreactor for Hydrogenation of Nitrobenzene

2016 ◽  
Author(s):  
Hao Feng ◽  
Xun Zhu ◽  
Rong Chen ◽  
Qiang Liao
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Microchannel Reactor ◽  
Two Phase ◽  
Modified Surface

In this study, visualization study on the gas-liquid two phase flow characteristics in a gas-liquid-solid microchannel reactor was carried out. Palladium nanocatalyst was coated onto the polydopamine functionalized surface of the microchannel through eletroless deposition. The materials characterization results indicated that palladium nanocatalyst were well dispersed on the modified surface. The effects of both the gas and liquid flow rates as well as inlet nitrobenzene concentration on the two-phase flow characteristics were studied. The experimental results revealed that owing to the chemical reaction inside the microreactor, the gas slug length gradually decreased along the flow direction. For a given inlet nitrobenzene concentration, increasing the liquid flow rate or decreasing the gas flow rate would make the variation of the gas slug length more obvious. High inlet nitrobenzene concentration would intensify both the nitrobenzene transfer efficiency and gas reactants consumption, and thereby the flow pattern in the microchannel was transferred from Taylor flow into bubble flow. Besides, the effect of both flow rate and original nitrobenzene concentration on the variation of nitrobenzene conversion and the desired product aniline yield were also discussed.

scholarly journals The influence of vapor on the particle transport in high humid neighborhood environment

2021 ◽  
Vol 2076 (1) ◽  
pp. 012043
Author(s):  
Dan Mei ◽  
Xuemei Xu
Keyword(s):  
Particle Transport ◽  
Street Canyon ◽  
Saturated Vapor ◽  
Flow Characteristics ◽  
Absolute Humidity ◽  
Neighborhood Environment ◽  
Computational Domain ◽  
Discrete Phase Model ◽  
Discrete Phase ◽  
Velocity Pressure

Abstract The particle transport characteristics have a significant effect on the exposure of residents and pedestrians to traffic pollutants in the street canyon. Around the lakeside environment, the diffusion of water vapor affects the flow characteristics of the gas mixture, which has a considerable influence on particle transport in the street canyon. A computational domain containing water bodies from which droplets were emitted by evaporation, a lakeside avenue and architectural groups were constructed. The RNG k-ε turbulence model and discrete phase model were applied to study the velocity, pressure, density of the airflow and particle transport characteristics in the street canyon with the absolute humidity increase (AHI) of 0, 3.8×10-4 g/kg, 1.7×10-3 g/kg, 3.1×10-3 g/kg. The saturated vapor pressure on the surface of droplets was modified by the pressure correction equation, which can limit the evaporation rate of the droplets. The simulation results demonstrated that, the diffusion of vapor could reduce the airflow velocity and increase the air pressure and density. The particle concentration in the street canyon increased with the AHI. Most of the pathogens in the air are transmitted with the flow of particle, and the study has some guiding significance to prevent the transmission of viruses.

Effect of particle mass concentration on erosion characteristics of self-priming pump

2021 ◽  
pp. 095440622110007
Author(s):  
Wenqi Zhang ◽  
Shuai Yang ◽  
Dazhuan Wu ◽  
Jiegang Mou
Keyword(s):  
Structural Damage ◽  
Leading Edge ◽  
Discrete Phase Model ◽  
Suction Surface ◽  
Two Phase ◽  
Lower Velocity ◽  
Damage And Failure ◽  
Discrete Phase ◽  
Flow Medium ◽  
Solid Liquid

The self-priming pump is widely used in conveying the solid-liquid two-phase flow medium. The particles in the medium erode the components, leading to structural damage and failure. The computational fluid dynamics (CFD) model of the 65ZW30-20 self-priming pump is built to study erosion characteristics and mechanisms. FLUENT, along with the Discrete Phase Model and Oka erosion model, is applied for the numerical simulation. The particle distribution, impact times and velocity, and trajectories are taken into consideration to investigate the erosion characteristics in each component. The results show that with the increase of the particle concentration, the head and efficiency decreases gradually. The volute wall and blade leading edge are the most vulnerable regions to erosion, because of a large number of impact times and high impact velocity. Also, the particles impact the front gap wall for fewer times and the hub with lower velocity, which leads to a slighter erosion. Besides, the particle trajectories indicate that some particles impact the blade suction surface and the paraxial area of the shroud, rendering considerable erosion.

scholarly journals Research on the flow characteristics of opening unit in the rotor spinning unit

2017 ◽  
Vol 25 (0) ◽  
pp. 18-24
Author(s):  
Yuzhen Jin ◽  
Shihe Zhu ◽  
Jingyu Cui ◽  
Jun Li ◽  
Zuchao Zhu
Keyword(s):  
Negative Pressure ◽  
Flow Characteristics ◽  
Axial Direction ◽  
Effective Area ◽  
Discrete Phase Model ◽  
Roller Speed ◽  
Rotor Spinning ◽  
Removal Process ◽  
Discrete Phase ◽  
Different Diameters

The opening unit is an important device in a rotor spinning unit to comb fibres and remove trash. In this paper, numerical simulation is carried out to study the flow structure in the rotor spinning channel and the trash removal process in the trash removal unit. Firstly the effect of the opening unit on the airflow field in the rotor channel is investigated by singlephase simulation. The result shows that the effective area for fibre conveyance enlarges as the absolute value of negative pressure at the outlet increases, while it decreases as the opening roller speed increases. However, the effect of the negative pressure and the opening roller speed on the length of the vortex in the axial direction is quite small. Secondly the trash separation process in the trash removal unit is simulated using the Discrete Phase Model (DPM). Suitable rotational speeds of particles of different diameters are acquired. These results could provide a valuable reference for parameter selection in the trash-removal process.

scholarly journals Numerical Simulation of Solid-Fluid 2-Phase-Flow of Cutting System for Cutter Suction Dredgers

2018 ◽  
Vol 25 (s2) ◽  
pp. 117-124 ◽  
Author(s):  
Min Zhang ◽  
Shidong Fan ◽  
Hanhua Zhua ◽  
Sen Han
Keyword(s):  
Flow Characteristics ◽  
Continuous Phase ◽  
Parameters Optimization ◽  
Phase Flow ◽  
Operational Parameters ◽  
Two Phase ◽  
Rotating Speed ◽  
Discrete Phase ◽  
Different Characteristics ◽  
Cutting System

Abstract The study of the flow characteristics of the solid-fluid two phase flow in the cutter suction dredger is very important for exploring the slurry formation mechanism and optimizing the operational parameters. In this study, standard k-ε model and Multiple Reference Frame are applied to numerically simulate flow field in and around the cutting system, then with the steady convergent result of the simulation as the initial condition, Discrete Phase Mode is used to solve the particle motion equation by fully coupling the continuous phase and the particles. The influence of suction flow velocity and cutter’s rotating speed on particles suction are analyzed, and effectively suctioned particles numbers are also quantitatively studied. The simulation result shows that the DPM model is able to simulate the movement of particles in and around the cutter suction dredger’s cutting system, in the fluid flow filed velocity vector and pressure distribution on different planes show different characteristics, and under higher suction velocity and lower cutter rotating speed more particles are suctioned into the suction inlet. The results can help better understand flow characteristics of solid-fluid 2-phase-flow of cutter suction dredger’s cutting system, and provide theoretical support for relative system design and operational parameters optimization.

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