Experimental and Numerical Investigation on Flow Characteristics of Large Cross-Sectional Ionic Wind Pump With Multiple Needles-to-Mesh Electrode

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
J. F. Zhang ◽  
S. Wang ◽  
M. J. Zeng ◽  
Z. G. Qu
Keyword(s):  
Breakdown Voltage ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Maximum Velocity ◽  
Simulation Method ◽  
Ionic Wind ◽  
Cross Sectional ◽  
Flexible Designs ◽  
Needle Diameter

Ionic wind pumps have attracted considerable interest because of their low energy consumption, compact structures, flexible designs, and lack of moving parts. However, large cross-sectional ionic wind pumps have yet to be numerically analyzed and experimentally optimized. Accordingly, this study develops a large cross-sectional ionic wind pump with multiple needles-to-mesh electrode, as well as analyzes its flow characteristics using a proposed full three-dimensional simulation method validated with experimental data. To obtain a considerably high outlet average velocity, experimental studies and numerical methods are employed to optimize the pump's configuration parameters, including needle electrode configuration, needle diameter, grid size, and gap between electrodes. The breakdown voltage and highest velocity corresponding to the breakdown voltage increase with an increase in the needle tip-to-mesh gap. After parametric optimization, a maximum velocity of 2.55 m/s and a flow rate of 2868 L/min are achieved.

scholarly journals Hydrodynamics of an in-pond raceway system with an aeration plug-flow device for application in aquaculture: an experimental study

2019 ◽  
Vol 6 (7) ◽  
pp. 182061 ◽  
Author(s):  
Wuhua Li ◽  
Xiangju Cheng ◽  
Jun Xie ◽  
Zhaoli Wang ◽  
Deguang Yu
Keyword(s):  
Water Flow ◽  
Plug Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
High Water ◽  
Secondary Flows ◽  
Commercial Application ◽  
Flow Device ◽  
Intensive Aquaculture

An in-pond raceway system (IPRS) is an effective intensive aquaculture practice for regions with high water consumption and limited land resources. Water flow and dissolved oxygen (DO) are important for sustainable aquaculture. Several innovations have been made in IPRS design and operation to increase water exchange and DO concentration; one of these is the aeration plug-flow device (APFD). The APFD is commonly used in China as the only power source for water recirculation in aquaculture ponds. Understanding of the hydrodynamics of the system is necessary to improve the design of the IPRS with APFD. To this end, we performed experimental studies on a model system. We measured three-dimensional velocity at various locations using an Acoustic Doppler Velocimeter. Velocity distribution and turbulence characteristics were assessed, and plug-flow characteristics were analysed. Two patterns of velocity and turbulence in horizontal sections were observed: near the APFD, the water flow was intensively pushed downstream and simultaneously recirculated; farther away, the reflux area gradually decreased and the velocity and turbulence distribution trended towards uniform. Secondary flows occurred in different directions, which improved the diffusion of materials and DO retention. The system is effectively self-circulating, and the plug-flow capability may be scaled up for commercial application.

Numerical Investigations of the Flow Characteristics in the Straight-Through Honeycomb Seal

2005 ◽  
Author(s):  
Jun Li ◽  
Qinghua Deng ◽  
Zhenping Feng
Keyword(s):  
Pressure Difference ◽  
Three Dimensional ◽  
Engineering Application ◽  
Flow Characteristics ◽  
Simulation Method ◽  
Labyrinth Seal ◽  
Honeycomb Structure ◽  
Computational Grids ◽  
Steam Turbines ◽  
Honeycomb Seal

Investigation of the flow characteristics in the straight-through honeycomb seal installed in the diagram for steam turbines using the numerical simulation method is presented in this paper. To illustrate the leakage flow performance of the straight-through honeycomb seal, the straight-through labyrinth seal with the same sealing clearance and pressure difference is also calculated. The flow fields are predicted using a commercial finite volume code with the standard k-ε turbulence model. The computational grids include the basic sealing geometries as well as the three-dimensional honeycomb seal and labyrinth seal structures. The obtained results demonstrate that the dimensionless discharge coefficient of the honeycomb seal is smaller than that of the labyrinth seal at the same sealing clearance and pressure difference. The leakage flows of the honeycomb seal are divided into much more smaller recirculation flows than that of the labyrinth seal due to its honeycomb structures. The honeycomb structure of the honeycomb seal leads to decrease the leakage mass flow rate. The flow characteristics of the honeycomb seal and labyrinth seal are also illustrated. This study can be able to supply the theoretical foundation and technical support for the engineering application of the honeycomb seal in steam turbines.

Effect of hourglass shape solder joints on underfill encapsulation process: numerical and experimental studies

2020 ◽  
Vol 32 (3) ◽  
pp. 147-156
Author(s):  
Muhammad Naqib Nashrudin ◽  
Zhong Li Gan ◽  
Aizat Abas ◽  
M.H.H. Ishak ◽  
M. Yusuf Tura Ali
Keyword(s):  
Solder Joint ◽  
Numerical Method ◽  
Flip Chip ◽  
Solder Joints ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Cross Sectional ◽  
Content Type ◽  
Filling Time ◽  
Encapsulation Process

Purpose In line with the recent development of flip-chip reliability and underfill process, this paper aims to comprehensively investigate the effect of different hourglass shape solder joint on underfill encapsulation process by mean of experimental and numerical method. Design/methodology/approach Lattice Boltzmann method (LBM) numerical was used for the three-dimensional simulation of underfill process. The effects of ball grid arrays (BGA) encapsulation process in terms of filling time of the fluid were investigated. Experiments were then carried out to validate the simulation results. Findings Hourglass shape solder joint has shown the shortest filling time for underfill process compared to truncated sphere. The underfill flow obtained from both simulation and experimental results are found to be in good agreement for the BGA model studied. The findings have also shown that the filling time of Hourglass 2 with parabolic shape gives faster filling time compared to the Hourglass 1 with hemisphere angle due to bigger cross-sectional area of void between the solder joints. Practical implications This paper provides reliable insights to the effect of hourglass shape BGA on the encapsulation process that will benefit future development of BGA packages. Originality/value LBM numerical method was implemented in this research to study the flow behaviour of an encapsulation process in term of filling time of hourglass shape BGA. To date, no research has been found to simulate the hourglass shape BGA using LBM.

Laminar Flow Characteristics in Entry Region in Microchannels

2008 ◽  
Author(s):  
Tiantian Zhang ◽  
Li Jia
Keyword(s):  
Surface Effect ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Maximum Velocity ◽  
Heat Sinks ◽  
Width Ratio ◽  
Hydrodynamic Diameter ◽  
Conventional Theory ◽  
Entry Length ◽  
Hydrodynamic Boundary Layer

A three-dimensional incompressible model of microchannel is proposed. Flow characteristics of nitrogen flow in different microchannels (hydraulic diameter ranging 100–500μm, the ratio of length-to-diameter ranging 60–150, the ratio of height-to-width ranging 0.2–1) have been investigated numerically. It is found that the velocity distribution in microchannels is obviously different from that in conventional channels, and the maximum velocity occurs not in the channel core as conventional theory expected but near the walls due to the surface effect. These phenomena result in the reduction of the thickness of hydrodynamic boundary layer. So the hydrodynamic entry length in microchannels is much larger than that in conventional channels. Theoretical analysis was given to explain these phenomena. The effects of Reynolds number, hydrodynamic diameter, length-to-diameter ratio and height-to-width ratio on hydrodynamic entry length were analyzed. The correlation between L/D and Re and height-to-width ratio, which is useful for designing and optimizing the microchannel heat sinks and other microfluidic devices, was suggested.

scholarly journals Computational analysis of high-lift-generating airfoils for diffuser-augmented wind turbines

2021 ◽  
Vol 6 (1) ◽  
pp. 149-157
Author(s):  
Aniruddha Deepak Paranjape ◽  
Anhad Singh Bajaj ◽  
Shaheen Thimmaiah Palanganda ◽  
Radha Parikh ◽  
Raahil Nayak ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Computational Analysis ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Two Dimensions ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Energy Access ◽  
Cross Sectional ◽  
High Lift

Abstract. The impetus towards sustainable energy production and energy access has led to considerable research and development on decentralized generators, in particular diffuser-augmented wind turbines. This paper aims to characterize the performance of diffuser-augmented wind turbines (DAWTs) using high-lift airfoils employing a three-step computational analysis. The study is based on computational fluid dynamics, and the analysis is carried out by solving the unsteady Reynolds-averaged Navier–Stokes (URANS) equations in two dimensions. The rotor blades are modeled as an actuator disk, across which a pressure drop is imposed analogous to a three-dimensional rotor. We study the change in performance of the enclosed turbine with varying diffuser cross-sectional geometry. In particular, this paper characterizes the effect of a flange on the flow augmentation provided by the diffuser. We conclude that at the end of the three-step analysis, Eppler 423 showed the maximum velocity augmentation.

Three-dimensional numerical simulation of velocity field distribution in an oxy-coal combustor-melter-separator furnace

2021 ◽  
Vol 118 (5) ◽  
pp. 510
Author(s):  
Yao-zong Shen ◽  
Kai Zhao ◽  
Zheng Kong ◽  
Yu-zhu Zhang ◽  
Yan Shi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Velocity Field ◽  
Velocity Distribution ◽  
Molten Pool ◽  
Dead Zone ◽  
Sudden Change ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Simulation Method ◽  
Distribution Area

In view of the influence of tuyere layout change on velocity field in oxy-coal combustor-melter-separator furnace, three-dimensional numerical simulation method was used to compare the distribution of velocity field in the furnace under different tuyere layout. The purpose is to explore the influence of the velocity distribution on the molten pool flow in the process of multi-tuyere injection. It is shown that the maximum velocity of the upper and lower tuyeres is 60 m/s and 50 m/s. And the change of tuyere has a significant effect on the velocity distribution in the molten pool, and the sudden change of velocity near the tuyere will trigger a certain scale of gyratory zone. In addition, the change of tuyere arrangement will result in the concentration of velocity distribution in the molten pool and the increase of flow dead zone, while the change of tuyere spacing will not only promote the increase of flow dead zone, but also reduce the velocity distribution area.

scholarly journals Simulation Analysis of Capacitance Method in Two-Phase Flow Concentration Measurement by Coupled Fields

2016 ◽  
Author(s):  
Xiaoxin Wang ◽  
Hongli Hu ◽  
Lin Li ◽  
Bo Wang
Keyword(s):  
Numerical Simulation ◽  
Two Phase Flow ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Simulation Method ◽  
Concentration Measurement ◽  
Phase Flow ◽  
Two Phase ◽  
Time Dynamic

This paper proposed three-dimensional numerical simulation method by coupling of electrostatic and fluid fields to evaluating the performance of electrical sensor in the concentration measurement of gas/solid two-phase flow. Compared with the static numerical simulation, this real-time dynamic 3-D simulation method can research on a designed capacitance sensor combining the dynamic characteristics of the two-phase flows for concentration measurement. Several fluid-electrostatic models of transmission pipes with different sensor structures are built. Under different test positions and different particle concentrations, the flow characteristics and the corresponding electric signals can be obtained, and the correlation coefficient between the concentration values and the capacitance values are used for performance evaluation of the sensors. The effects of flow regimes on concentration measurement are also been investigated in this paper. To validate the results of simulation, an experimental platform with horizontal straight pipe for phase volume concentration measurement of solid/air two-phase flow is built, and the experimental results agree well with simulation conclusions. The simulation and test results show that the coupling models can give constructive reference opinions for the sensor design and collection of installation position in different transmission pipelines, which are very important for the practical process of pneumatic conveying system.

Three-Dimensional Free Jets

1967 ◽  
Vol 71 (684) ◽  
pp. 858-859
Author(s):  
N. Rajaratnam ◽  
K. Subramanya
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Maximum Velocity ◽  
Potential Core ◽  
Free Jets ◽  
Axisymmetric Jet ◽  
Plane Jets ◽  
Velocity Decay ◽  
Different Shapes ◽  
Semi Empirical

Fairly elegant semi-empirical theories are available for predicting the turbulent diffusion of axisymmetric and plane jets. However, there are relatively few investigations on the non-axisymmetric jets, herein denoted as three-dimensional jets. The extensive investigations conducted at the Polytechnic Institute of Brooklyn on three-dimensional jets have shown that the flow field is characterised by three distinct regions; the potential core, the characteristic decay (CD) region and the axisymmetric decay (AD) region. In the CD region the velocity profiles in the direction of the minor axis are similar but the maximum velocity decay curves are different for different shapes. In the AD region the flow characteristics are similar to that of an axisymmetric jet. Yevdjevich has recently conducted another investigation on rectangular jets.

scholarly journals Ethical Aspects of Brain Organoid Research in News Reports: An Exploratory Descriptive Analysis

Medicina ◽  
2021 ◽  
Vol 57 (6) ◽  
pp. 532
Author(s):  
Kazuki Ide ◽  
Norihiro Matsuoka ◽  
Misao Fujita
Keyword(s):  
Public Perception ◽  
Descriptive Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
The United States ◽  
Ethical Aspects ◽  
Cross Sectional ◽  
The Public ◽  
News Reports ◽  
Brain Organoid

Background and Objectives: Brain organoids are self-assembled, three-dimensional (3D) aggregates generated from pluripotent stem cells. These models are useful for experimental studies on human brain development and function and are therefore increasingly used for research worldwide. As their increasing use raises several ethical questions, we aimed to assess the current state of the press on brain organoid research using a cross-sectional database to understand the extent of discussion of this subject in the public. Materials and Methods: We conducted a descriptive analysis of news reports obtained from the Nexis Uni database, searched in April 2020. After extracting the news reports, the number of published reports in each year and the included terms were analyzed. Results: Up to April 2020, 332 news reports had been published, with over half of them published in the United States and the United Kingdom, with the numbers gradually increasing every year. In total, 113 (34.0%) news reports included ethics-related keywords, and the ratio of studies before and after the study-period midpoint was significantly increased (21.0% (2013–2016) vs. 38.2% (2017–2020); p = 0.0066, Chi-square test with Yates’ continuity correction). Conclusions: Although news reports on the ethical aspects of brain organoid research have been increasing gradually, there was a bias in the region of publication. Additional studies focusing on the ethical aspects of brain organoid research should strive to assess the public perception on the subject in different parts of the world.

scholarly journals Three Dimensional Flow Simulation in Yarn Duct of Interlacers with Various Cross-Sectional Shapes

2012 ◽  
Vol 7 (3) ◽  
pp. 155892501200700
Author(s):  
Qiu Hua ◽  
Yan Jin
Keyword(s):  
Cross Section ◽  
Software Package ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
Three Dimensional Flow ◽  
Cross Sectional ◽  
Ansys Cfx ◽  
Middle Cross Section ◽  
The Relationship

This goal of this paper was to determine the flow characteristics of compressible airflow in the yarn duct of an interlacer using numerical simulations to study the effects of cross-sectional shapes of yarn duct on the performance of interlacers. A CFD (Computational Fluid Dynamics) software package ANSYS CFX was used to calculate the flow patterns in the yarn duct. The relationship between the performance of the interlacer and the distribution of the velocity vector, the airflow speed and the particle trace of flow were examined in order to propose a better design of interlacers. From the results of the calculations, if the vortices on the middle cross-section of the yarn duct make the filaments revolve continuously, then a large number of entanglements can be achieved. The velocity at the central point of the yarn duct was the deciding factor as to a sufficient opening for the filaments. However, too high of a velocity makes the filaments stay on the wall, hindering them from entangling with each other.

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