Development of Ink-Particle Flight Simulation for Continuous Inkjet Printers

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Masato Ikegawa ◽  
Eiji Ishii ◽  
Nobuhiro Harada ◽  
Tsuneaki Takagishi
Keyword(s):  
Fluid Dynamics ◽  
Electric Field ◽  
Drag Force ◽  
High Speed ◽  
Electrostatic Force ◽  
Flight Simulation ◽  
High Speed Camera ◽  
Inkjet Printers ◽  
Simulation Results ◽  
Good Agreement

A method of simulating ink-particle flight for industrial, continuous inkjet printers (CIJPs) was developed to clarify the factors that influence print distortion. Print distortion is produced by aerodynamic and electric interference between the ink-particles flying from the nozzle onto the print target. The necessary functions to do this, such as the calculation of electrostatic force in the electric field between the electrodes, Coulomb's force from other charged ink-particles, and the drag force in the inkjet stream for many flying ink-particles were added to a Lagrangian method in the software to analyze the fluid dynamics that was used in the simulations. The trajectories of the ink particles flying from the nozzle onto the print target and the air flow caused by them were simultaneously calculated in the simulations. The results from simulations for the velocities and trajectories of the flying ink particles were compared with the experimental ones obtained with a high-speed camera. These simulation results were in good agreement with the experimental ones, and the developed simulation helps to clarify the factors that influence print distortion and to create algorithms that decrease it.

Development of Ink-Particle Flight Simulation for Continuous Inkjet Printer

2013 ◽  
Author(s):  
Masato Ikegawa ◽  
Eiji Ishii ◽  
Nobuhiro Harada ◽  
Tsuneaki Takagishi
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Electrostatic Force ◽  
Simulation Method ◽  
Flight Simulation ◽  
Analysis Software ◽  
Continuous Type ◽  
Inkjet Printers ◽  
Simulation Results ◽  
Good Agreement

An ink-particle flight simulation method for industrial, continuous-type inkjet printers was developed to clarify the factors that influence the print distortion. Print distortion is produced by aerodynamic and electric interference between the ink-particles flying from the nozzle onto the print-target. The necessary functions to do this, such as the calculation of electrostatic force in the electric field between the electrodes, the Coulomb’s force from other charged ink-particles, and the drag force in the inkjet stream for many flying ink-particles were added to a Lagrangian method in the fluid dynamic analysis software that was used for the simulation. The trajectories of the ink-particles flying from this nozzle onto the print target and the air-flow caused by them were calculated simultaneously in the simulation. The simulation results for the velocities and trajectories of the flying ink-particles were compared with the experimental ones using a high-speed camera. These simulation results were in good agreement with the experimental ones, and this helps to clarify the factors that influence the print distortion.

Transient Computational Fluid Dynamics/Discrete Element Method Simulation of Gas–Solid Flow in a Spouted Bed and Its Validation by High-Speed Imaging Experiment

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Ling Zhou ◽  
Lingjie Zhang ◽  
Weidong Shi ◽  
Ramesh Agarwal ◽  
Wei Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Discrete Element Method ◽  
Fluidized Bed ◽  
High Speed ◽  
Discrete Element ◽  
Bubble Shape ◽  
High Speed Imaging ◽  
Bed Height ◽  
Simulation Results

A coupled computational fluid dynamics (CFD)/discrete element method (DEM) is used to simulate the gas–solid two-phase flow in a laboratory-scale spouted fluidized bed. Transient experimental results in the spouted fluidized bed are obtained in a special test rig using the high-speed imaging technique. The computational domain of the quasi-three-dimensional (3D) spouted fluidized bed is simulated using the commercial CFD flow solver ANSYS-fluent. Hydrodynamic flow field is computed by solving the incompressible continuity and Navier–Stokes equations, while the motion of the solid particles is modeled by the Newtonian equations of motion. Thus, an Eulerian–Lagrangian approach is used to couple the hydrodynamics with the particle dynamics. The bed height, bubble shape, and static pressure are compared between the simulation and the experiment. At the initial stage of fluidization, the simulation results are in a very good agreement with the experimental results; the bed height and the bubble shape are almost identical. However, the bubble diameter and the height of the bed are slightly smaller than in the experimental measurements near the stage of bubble breakup. The simulation results with their experimental validation demonstrate that the CFD/DEM coupled method can be successfully used to simulate the transient gas–solid flow behavior in a fluidized bed which is not possible to simulate accurately using the granular approach of purely Euler simulation. This work should help in gaining deeper insight into the spouted fluidized bed behavior to determine best practices for further modeling and design of the industrial scale fluidized beds.

scholarly journals Beer mats make bad frisbees

2021 ◽  
Vol 136 (7) ◽  
Author(s):  
Johann Ostmeyer ◽  
Christoph Schürmann ◽  
Carsten Urbach
Keyword(s):  
Approximate Solution ◽  
High Speed ◽  
Center Of Mass ◽  
Effective Theory ◽  
High Speed Camera ◽  
Minimal Set ◽  
Crucial Effect ◽  
Forward Edge ◽  
Theoretical Results ◽  
Good Agreement

AbstractIn this article we show why flying and rotating beer mats, CDs, or other flat disks will eventually flip in the air and end up flying with backspin, thus, making them unusable as frisbees. The crucial effect responsible for the flipping is found to be the lift attacking not in the center of mass but slightly offset to the forward edge. This induces a torque leading to a precession towards backspin orientation. An effective theory is developed providing an approximate solution for the disk’s trajectory with a minimal set of parameters. Our theoretical results are confronted with experimental results obtained using a beer mat shooting apparatus and a high speed camera. Very good agreement is found.

scholarly journals CFD analysis on the aerodynamics characteristics of Jakarta-Bandung high speed train

2018 ◽  
Vol 159 ◽  
pp. 02038 ◽  
Author(s):  
Tony Utomo ◽  
Berkah Fajar ◽  
Hendry Arpriyanto
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
High Speed ◽  
Computational Domain ◽  
Cfd Analysis ◽  
High Speed Train ◽  
Pressure Area ◽  
Train Speed ◽  
Simulation Results

In this study, the aerodynamics characteristics of HST type CRH380A which is planned to be operated on the new railway of Jakarta-Bandung are analysed using Computational Fluid Dynamics. The speed of the train in this simulation was varied from 100 km/h to a maximum designed speed of 350 km/h with the increment of 30 km/h. The train was modelled in 3D computational domain with more than 1.7 million cells. The turbulence model employed in this study was standard k-ω. The simulation results show that the drag coefficient (CD) is slightly decrease by the increase of speed. At the speed of 100 km/h the CD is 0.216 and decrease to 0.188 at the speed of 350 km/h. The high pressure area is located at the nose of the train. The pressure acting on this location is increase with the increase of the train speed.

scholarly journals Numerical Investigation on Cooling of Small Form Factor Computer Cases

2007 ◽  
Author(s):  
O¨mer Emre Orhan ◽  
I˙lker Tarı
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Form Factor ◽  
Small Form ◽  
Discretization Schemes ◽  
Simulation Results ◽  
Small Form Factor ◽  
Grid Selection ◽  
Physical Phenomena ◽  
Good Agreement

In this study, cooling of small form factor computers is numerically investigated. The numerical model is analyzed using a commercial finite volume computational fluid dynamics software package. The effects of grid selection, discretization schemes and turbulence model selection on simulation results are discussed. In addition, recirculation and relaminarization are addressed briefly as examples of physical phenomena affecting cooling. For a comparison with the computational fluid dynamics results, an experiment is conducted and some temperature measurements are obtained from critical locations inside the chassis. The computational results were found to be in good agreement with the experimental ones.

The Effect of Stratification Ratio on the Macrostructure of Stratified Swirl Flames: Experimental and Numerical Study

2018 ◽  
Author(s):  
Xiao Han ◽  
Davide Laera ◽  
Aimee S. Morgans ◽  
Yuzhen Lin ◽  
Chih-Jen Sung
Keyword(s):  
Fluid Dynamics ◽  
Numerical Study ◽  
Large Eddy Simulations ◽  
Flame Dynamics ◽  
Large Eddy ◽  
Swirling Flame ◽  
Different Shapes ◽  
Flame Quenching ◽  
Simulation Results ◽  
Good Agreement

The present article reports experimental and numerical analyses of the macrostructures featured by a stratified swirling flame for varying stratification ratio (SR). The studies are performed with the Beihang Axial Swirler Independently-Stratified (BASIS) burner, a novel double-swirled full-scale burner developed at Beihang University. Experimentally, it is found that depending on the ratio between the equivalence ratios of the methane-air mixtures from the two swirlers, the flame stabilizes with three different shapes: attached V–flame, attached stratified flame and lifted flame. In order to better understand the mechanisms leading to the three macrostructures, large eddy simulations (LES) simulations are performed via the open source Computational Fluid Dynamics software OpenFOAM using the incompressible solver Reacting Foam. Changing the SR, simulation results show good agreement with experimentally observed time-averaged flame shapes, demonstrating that the incompressible LES are able to fully characterize the different flame behaviours observed in stratified burners. When the LES account for heat loss from walls, they better capture the experimentally observed flame quenching in the outer shear layer. Finally, insights into the flame dynamics are provided by analysing probes located near the two separate streams.

Design, fabrication and characterization of an electrical-explosively actuated MEMS flyer-accelerator inserted with parallel bridge foils

2020 ◽  
Vol 91 (1) ◽  
pp. 10301
Author(s):  
Zhi Yang ◽  
Guoqiang Zheng ◽  
Peng Zhu ◽  
Cong Xu ◽  
Qiu Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Electrical Explosion ◽  
Enhancement Effect ◽  
High Speed Camera ◽  
And Shock Waves ◽  
Test Circuit ◽  
Mems Technology ◽  
Fabrication And Characterization ◽  
Good Agreement

Parallel bridge foils (PBF) with four strip foils, which is derived from traditional single bridge foil (SBF), was designed to study the effect of convergence and collision of plasmas and shock waves on driving flyer. Firstly, Electro-thermal simulation of PBF was performed to analyze temperature distribution before melting, which predicted the synchronous burst characteristic of PBF. Subsequently, a capacitor discharging circuit was designed to initiate bridge foils, results indicated PBF reached higher burst power in shorter time compared with SBF due to better matching between PBF and the test circuit. The flow fields of electrical explosion of bridge foils were photographed by ultra-high-speed camera, which displayed PBF almost burst simultaneously. Moreover, PBF had wider and brighter flow field visualization than SBF owing to convergence and superposition of plasma beams. Most importantly, flyer-accelerators inserted with bridge foils were prepared by MEMS technology, and comparative analysis from PDV revealed MEMS flyer-accelerator inserted with PBF had access to better velocity performances, compared with that inserted with SBF. For instance, PBF flyer-accelerator spent mere 168 ns to 2325 m/s at 900 V/0.22 µF, but SBF flyer-accelerator took 335 ns to 1073 m/s. Finally, we proposed a mathematical model for explaining the enhancement effect of flyer velocity, which to some extent showed good agreement with experimentation.

Effect of the inter-car gap length on the aerodynamic characteristics of a high-speed train

2018 ◽  
Vol 233 (4) ◽  
pp. 448-465 ◽  
Author(s):  
Tian Li ◽  
Ming Li ◽  
Zheng Wang ◽  
Jiye Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Drag Force ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Wind Tunnel Experiments ◽  
The Impact

In wind tunnel experiments, the inter-car gaps are designed in such a way as to separate the force measurements for each car and prevent the interference between cars during tests. Moreover, the inter-car gap has a significant effect on the aerodynamic drag of a train. In order to guide the design of the inter-car gaps between cars in wind tunnel experiments, the impact of the inter-car gap length on the aerodynamic characteristics of a 1/8th scale high-speed train is investigated using computational fluid dynamics. The shear stress transport k-ω model is used to simulate the flow around a high-speed train. The aerodynamic characteristics of the train with 10 different inter-car gap lengths are numerically simulated and compared. The 10 different inter-car gap lengths are 5, 8, 10, 15, 20, 30, 40, 50, 60, and 80 mm. Results indicate that the aerodynamic drag coefficients obtained using computational fluid dynamics fit the experimental data well. Rapid pressure variations appear in the upper and lower parts of the inter-car gaps. With the increase of the inter-car gap length, the drag force coefficient of the head car gradually increases. The total drag force coefficients of the trains with the inter-car gap length less than 10 mm are practically equal to those of the trains without inter-car gaps. Therefore, it can be concluded from the present study that 10 mm is recommended as the inter-car gap length for the 1/8th scale high-speed train models in wind tunnel experiments.

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