Effect of position of the fiber transport channel on fiber motion in the high-speed rotor

2021 ◽  
pp. 004051752110018
Author(s):  
Rui Hua Yang ◽  
Chuang He ◽  
Bo Pan ◽  
Hongxiu Zhong ◽  
Cundong Xu
Keyword(s):  
High Speed ◽  
Channel Model ◽  
Three Dimensional ◽  
Discrete Phase Model ◽  
Transport Channel ◽  
Rotor Spinning ◽  
Fiber Motion ◽  
Discrete Phase ◽  
Airflow Field ◽  
Fiber Transport

The task of the fiber transport channel (FTC) is to transport the fibers from the carding roller to the rotor. Its geometric position in the spinning machine has a strong influence on the characteristics of the airflow field and the trajectory of the fiber motion in both the rotor and the FTC. In this paper, a three-dimensional pumping rotor spinning channel model was established using ANSYS-ICEM-CFD software with three different positions of the FTC (positions a–c). Further, the simulations of air distribution were performed using Fluent software. In addition, the discrete phase model was used to fit the fiber motion trajectory in the rotor. The simulation results showed that among the three types of FTC, position b is the optimal condition. The gradients of airflow velocity in the channel at position b were greater than those of the other two positions, which is conducive to straightening of the fiber.

Numerical study on the anti-snow performance of deflectors in the bogie region of a high-speed train using the discrete phase model

2018 ◽  
Vol 233 (2) ◽  
pp. 141-159 ◽  
Author(s):  
Guangjun Gao ◽  
Yan Zhang ◽  
Fei Xie ◽  
Jie Zhang ◽  
Kan He ◽  
...  
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Snow Accumulation ◽  
Phase Model ◽  
High Speed Train ◽  
Discrete Phase Model ◽  
Discrete Phase ◽  
Deflector Plate

In this paper, the three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with an RNG double-equation turbulence model and a discrete phase model were used for the investigation of snow accumulation on the bogie of a high-speed train. Two kinds of deflector plates, one installed at the front end and the other at the rear end of the bogie, were proposed to reduce snow accumulation. The accuracy of the CFD methodology was validated against wind tunnel tests. The results showed that high-speed air will impact the plates where snow particles get accumulated. The snow covering on the bogie rarely drifts back into the bogie region with air. The amount of accumulating snow in the optimum models is reduced by 50.58% on average as compared to those in the original models. At the rear end of the bogie, the inclined deflector plate reduced snow accumulation by up to 10.91% compared to the vertical deflector plate.

A numerical study of snow accumulation on the bogies of high-speed trains based on coupling improved delayed detached eddy simulation and discrete phase model

2018 ◽  
Vol 233 (7) ◽  
pp. 715-730 ◽  
Author(s):  
Mingyang Liu ◽  
Jiabin Wang ◽  
Huifen Zhu ◽  
Sinisa Krajnovic ◽  
Guangjun Gao
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Snow Accumulation ◽  
Phase Model ◽  
Detached Eddy Simulation ◽  
Discrete Phase Model ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Flow Mechanisms ◽  
Discrete Phase

A numerical simulation method based on the improved delayed detached eddy simulation coupled with a discrete phase model is used to study the influence of the snow on the performance of bogies of a high-speed train running in snowy weather. The snow particle trajectories, mass of snow packing on the bogie, and thickness of snow accumulation have been analyzed to investigate the flow mechanisms of snow accumulation on different parts of the bogies. The results show that the snow accumulation on the first bogie of the head vehicle is almost the same as that of the second bogie, but the total accumulated snow on the top side of the second bogie is more than 74% higher than that of the first bogie. Among all the components of the bogies, the motors were found to be strongly influenced by the snow accumulation. The underlying flow mechanisms responsible for the snow accumulations are discussed.

Numerical simulation of the airflow field in vortex spinning processing

2018 ◽  
Vol 89 (6) ◽  
pp. 1113-1127 ◽  
Author(s):  
Shanshan Shang ◽  
Jianping Yang ◽  
Chongwen Yu
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Stable Process ◽  
Three Dimensional ◽  
Experimental Result ◽  
Initial State ◽  
Suction Force ◽  
Spinning Process ◽  
Airflow Field ◽  
Yarn Tenacity

Three-dimensional numerical simulation of the airflow characteristics during the whole vortex spinning process, including the initial state of the yarn drawing-in process and the normal stable process, were obtained and analyzed. Spinning experiments, with the aid of a scanning electron microscope, were adopted to verify the results of the numerical simulation. The numerical simulation results show that the turbulence phenomenon in the normal spinning process is much more obvious than that in the initial spinning process; the air streamlines move orderly in the initial spinning process, which will produce a strong suction force that will be conducive to drawing the fiber bundle into the nozzle successfully, but the trajectory of airflow is complex in the normal stable spinning process and there is an upstream airflow with the same direction as the rotating airflow to provide extra tension for the yarn, which can improve the strength of the resultant yarn. The spinning experimental result is consistent with the result predicted by numerical simulation. The research further reveals the flow regularity and the turbulent phenomenon of the high-speed rotating airflow, predicts the effect of airflow motion on the spinning effect, and is helpful for stabilizing the spinning process and improving the yarn tenacity.

A Numerical Study of Particle Deposition Through Fuel Pebble Bed in HTGR

2018 ◽  
Author(s):  
Qi Sun ◽  
Gang Zhao ◽  
Wei Peng ◽  
Suyuan Yu
Keyword(s):  
Particle Deposition ◽  
Numerical Study ◽  
Three Dimensional ◽  
Intensity Change ◽  
Discrete Phase Model ◽  
Pebble Bed ◽  
Deposition Fraction ◽  
Discrete Phase ◽  
Face Centered ◽  
Fuel Elements

The study on the deposition of graphite dust is significant to the safety of High-Temperature Gas-cooled Reactor (HTGR) due to potential accident such as localized hot-spots and intensity change which is caused by the graphite dust generated by abrasion of fuel elements. Based on the steady flow and three-dimensional face centered structures of fuel pebble bed, the discrete phase model (DPM) were applied to simulate trajectory of graphite dust in conditions of HTGR. To determinate the deposition of particle, the present study introduces a rebound condition with critical velocity by a user defined function. The particle trajectories show most of particle deposition can be summed up as the effect of backflow region, turbulent diffusion and inertial impact. The original trap condition overestimates the deposition fraction especially for large particles compared with involving rebound condition. In addition, the trend of deposition fraction shows as the dimeter of particle increases, deposition fraction decreases first and then increases.

A numerical investigation on the improvement of anti-snow performance of the bogies of a high-speed train

2019 ◽  
Vol 234 (10) ◽  
pp. 1319-1334 ◽  
Author(s):  
Jiabin Wang ◽  
Yan Zhang ◽  
Jie Zhang ◽  
Xifeng Liang ◽  
Sinisa Krajnović ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
High Speed ◽  
Weather Conditions ◽  
Snow Accumulation ◽  
Navier Stokes ◽  
High Speed Train ◽  
Discrete Phase Model ◽  
Flow Features ◽  
High Speed Trains ◽  
Discrete Phase

In this paper, numerical simulations combining unsteady Reynolds-averaged Navier-Stokes (URANS) simulation and the discrete phase model are used to study the application of countermeasure for snow accumulation in the regions of bogie cavities of a high-speed train. The influence of the cowcatcher heights and guide structure configurations on the flow features and snow accumulation was studied. The results of the study show that the cowcatcher with a downward elongation of 4% of the distance between the two axles decreases the snow accumulation in the first and the second bogie regions by about 56.6% and 13.6%, respectively. Furthermore, the guide structures have been found to significantly alter the velocity and pressure distribution in the second bogie region, resulting in a relatively large snow-accumulation reduction. The deflector is found to perform better in reducing snow accumulation when compared to the diversion slots. The cowcatcher, elongated in the downward direction, and the deflector proved to be a good countermeasure for snow accumulation around the bogies of high-speed trains operating in snowy weather conditions.

Numerical Calculation on the Influence of Missile Exhaust Plume with Mechanical Properties to the Double-Launch Box

2014 ◽  
Vol 978 ◽  
pp. 101-105
Author(s):  
Jing Li ◽  
Yi Jiang
Keyword(s):  
Three Dimensional ◽  
Engineering Application ◽  
Maximum Pressure ◽  
Common Phenomenon ◽  
Discrete Phase Model ◽  
Exhaust Plume ◽  
Discrete Phase ◽  
Unsteady Numerical Simulation ◽  
Multicomponent Model ◽  
Over Time

The adverse impact of the exhaust plume on the inner wall of the vertical launch box and the former friable lid of the adjacent launch box is a common phenomenon, which causes the deformation or damage of the launch container. By using the three-dimensional unsteady numerical simulation, discrete phase model and multicomponent model, the change of the pressure and temperature with time on many monitoring sites are analyzed. The results show that the pressure and the temperature on the edge of the inner wall significantly rise over time after 0.2s. The pressure on the centerline of the inner wall rises over time after 0.2s but the temperature gradually decreases. The maximum pressure on the former friable lid of the adjacent launch box peaks at 0.54s. The conclusion can be regarded as a theoretical reference for engineering application.

Anti-snow performance of snow shields designed for brake calipers of a high-speed train

2018 ◽  
Vol 233 (2) ◽  
pp. 121-140 ◽  
Author(s):  
Jiabin Wang ◽  
Guangjun Gao ◽  
Yan Zhang ◽  
Kan He ◽  
Jie Zhang
Keyword(s):  
High Speed ◽  
Snow Accumulation ◽  
Cold Weather ◽  
High Speed Train ◽  
Detached Eddy Simulation ◽  
Discrete Phase Model ◽  
Railway Line ◽  
Eddy Simulation ◽  
Flow Features ◽  
Discrete Phase

When high-speed trains run on a snowy railway line in cold weather, a large amount of snow and ice will accumulate on the brake calipers, which can lead to huge safety problems. In this paper, to solve this issue, a numerical method based on the detached eddy simulation was used to explore the flow features of a high-speed train running in cold weather. The accuracy of mesh resolution and methodology of Computational Fluid Dynamics (CFD) was validated against the wind tunnel tests. A discrete phase model was used to investigate the process of snow accumulation on the brake calipers by analysing the movement characteristics of snow particles. Based on this analysis, three kinds of anti-snow packing shields for the brake calipers were designed, and the shielding effects were compared via numerical simulations. The results show that a large amount of snow particles below the bogie directly impact the brake calipers causing massive snow packing on the bottom surfaces; some snow particles reflected from the rear equipment cabin cover return to the bogie region and accumulates on the upper surfaces. With the application of anti-snow packing shields with trapezoidal-, triangular- and cambered-shaped openings, the rates of snow accumulation on the brake calipers were reduced by 18.53, 26.68 and 38.81%, respectively. The cambered type provides the best anti-snow packing performance for the brake calipers.

scholarly journals The Airflow Field Characteristics of the Unmanned Agricultural Aerial System on Oilseed Rape (Brassica napus) Canopy for Supplementary Pollination

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2035
Author(s):  
Songchao Zhang ◽  
Chen Cai ◽  
Jiqiang Li ◽  
Tao Sun ◽  
Xiaoming Liu ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Seed Production ◽  
Oilseed Rape ◽  
High Speed ◽  
Field Experiments ◽  
Three Dimensional ◽  
Flight Path ◽  
Distribution Law ◽  
Pollination Success ◽  
Airflow Field

Pollination success is essential for hybrid oilseed rape (OSR, Brassica napus) seed production, but traditional pollination methods are not efficient. The unmanned agricultural aerial system (UAAS) has developed rapidly and has been widely used in China. When flying, the wind field generated by the rotors overcomes the UAAS gravity, and it blows and disturbs the crops below, which helps the pollen spread. In order to investigate the distribution law of the three-dimensional (direction x, y, z) airflow field, experiments involving three levels of flight speed (FS) at 4.0, 5.0, and 6.0 m/s, and three levels of flight height (FH) at 1.5, 2.0, and 2.5 m were conducted in the OSR field by using an electric four-rotor UAAS P20. The effects of FS and FH on airflow velocities (, , ) were analyzed. High-speed dynamic camera (HSDC) technology was used to capture the swings of OSR plants under airflow field disturbance. OSR pollen samples were collected during the experiments. The results showed that the airflow field in the direction x was mainly concentrated on the center of the flight path (S3), and the maximum wind velocity of direction x was 8.01 m/s (T1, S3). The direction x airflow field width was distributed almost symmetrically, but the center position shifted easily, due to crosswind. The airflow field in the direction y was distributed on both sides of the center flight path, and the velocity was generally larger, with the maximum at 7.91 m/s (T1, S2). The airflow field in the direction z was distributed irregularly, and the velocity was small. The FH had highly significant impacts on (p < 0.01), and the interaction of FS and FH had significant impacts on (0.01 < p < 0.05), while the FS had no significant impact on (p = 0.70804 > 0.05). The FS, FH, and interaction of FS and FH all had highly significant impacts on (p < 0.01). The swings of the OSR plant captured by the HSDC proved that the UAAS airflow field could effectively blow the OSR plant. The swing amplitude changes showed a positive correlation with airflow velocities () in general. Although the observed OSR plant swung forward and backward repeatedly, there was a law of first forward, and then backward, and forward again at the beginning of each swing. The pollen collected on the sampler verified that the UAAS airflow field could help with pollen spread. The research results provide technical support for UAAS application on supplementary pollination for hybrid OSR seed production.

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.

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