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

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.

Download Full-text

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

Textile Research Journal ◽

10.1177/00405175211001804 ◽

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.

Download Full-text

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

Journal of Physics Conference Series ◽

10.1088/1742-6596/2076/1/012043 ◽

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.

Download Full-text

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

Processes ◽

10.3390/pr8111512 ◽

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.

Download Full-text

Effects of Blade Parameters on the Flow Field and Classification Performance of the Vertical Roller Mill via Numerical Investigations

Mathematical Problems in Engineering ◽

10.1155/2020/3290694 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Chang Liu ◽

Zuobing Chen ◽

Weili Zhang ◽

Chenggang Yang ◽

Ya Mao ◽

...

Keyword(s):

Flow Field ◽

Pressure Difference ◽

Continuous Phase ◽

Classification Performance ◽

Field Analysis ◽

Discrete Phase Model ◽

Roller Mill ◽

Discrete Phase ◽

Vertical Roller ◽

Classification Efficiency

The vertical roller mill is an important crushing and grading screening device widely used in many industries. Its classification efficiency and the pressure difference determine the entire producing capacity and power consumption, respectively, which makes them the two key indicators describing the mill performance. Based on the DPM (Discrete Phase Model) and continuous phase coupling model, the flow field characteristics in the vertical roller mill including the velocity and pressure fields and the discrete phase distributions had been analyzed. The influence of blade parameters like the shape, number, and rotating speed on the flow field and classification performance had also been comprehensively explored. The numerical simulations showed that there are vortices in many zones in the mill and the blades are of great significance to the mill performance. The blade IV not only results in high classification efficiency but also reduces effectively the pressure difference in the separator and also the whole machine. The conclusions of the flow field analysis and the blade effects on the classification efficiency and the pressure difference could guide designing and optimizing the equipment structure and the milling process, which is of great importance to obtain better overall performance of the vertical roller mill.

Download Full-text

Random pore structure and REV scale flow analysis of engine particulate filter based on LBM

Open Physics ◽

10.1515/phys-2020-0208 ◽

2020 ◽

Vol 18 (1) ◽

pp. 881-896

Author(s):

Chunrui Wu ◽

Tiechen Zhang ◽

Jiale Fu ◽

Xiaori Liu ◽

Boxiong Shen

Keyword(s):

Single Channel ◽

Flow Analysis ◽

Flow Characteristics ◽

Axial Direction ◽

Particulate Filter ◽

Random Structure ◽

Structure Generation ◽

Inlet Flow ◽

Random Structures ◽

Boltzmann Method

Abstract In this article, lattice Boltzmann method (LBM) is used to simulate the multi-scale flow characteristics of the engine particulate filter at the pore scale and the representative elementary volume (REV) scale, respectively. Four kinds of random wall-pore structures are considered, which are circular random structure, square random structure, isotropic quartet structure generation set (QSGS), and anisotropic QSGS, with difference analysis done. In terms of the REV scale, the influence of different inlet flow velocities and wall permeabilities on the flow in single channel is analyzed. The result indicates that the internal seepage laws of random structures constructed in this article and single channel are in accordance with Darcy’s law. Circular random structure has better permeability than square random structure. Isotropic QSGS has better fluidity than anisotropic one. The flow in single channel is similar to Poiseuille flow. The flow lines in the channel are complicated and a large number of vortices appear at the ends of channel with high inlet flow rate. With the increase of inlet velocity, the static pressure in channel gradually increases along the axial direction as well as the seepage velocity. The temperature field in the channel becomes more uniform as the flow velocity increases, and the higher temperature distribution appears on the wall of the porous media.

Download Full-text

Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress

Science Progress ◽

10.1177/00368504211008064 ◽

2021 ◽

Vol 104 (1) ◽

pp. 003685042110080

Author(s):

Zheqin Yu ◽

Jianping Tan ◽

Shuai Wang

Keyword(s):

Blood Flow ◽

Shear Stress ◽

Multiphase Flow ◽

Experimental Verification ◽

Flow Simulation ◽

Turbulence Models ◽

Phase Model ◽

Force Model ◽

Discrete Phase Model ◽

Discrete Phase

Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k- ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.

Download Full-text