scholarly journals Particle Imaging Velocimetry Measurement of Air Flow Between High Voltage Asymmetrical Electrodes

2020 ◽  
Vol 328 ◽  
pp. 05007
Author(s):  
Jiří Primas ◽  
Michal Malík ◽  
Petr Schovanec ◽  
Josef Novák ◽  
Pavel Pokorný ◽  
...  
Keyword(s):  
Electric Fields ◽  
Particle Image ◽  
Theoretical Description ◽  
Dc Voltage ◽  
Practical Applications ◽  
Image Velocimetry ◽  
Particle Imaging Velocimetry Measurement ◽  
Strong Electric Fields ◽  
The Many ◽  
Particle Imaging

This paper deals with the airflow generation phenomenon occurring on a system of strongly asymmetrical electrodes connected to high DC voltage. The main focus was to measure the airflow directly between the electrodes using Particle Image Velocimetry. The authors are well aware of the many difficulties presented by the task of measuring in the presence of strong electric fields and the paper also describes the means used to overcome these issues. The results of performed measurements are presented, their agreement with theoretical description of given phenomenon is discussed and several possible practical applications are proposed.

scholarly journals Possible Limitations of the Particle Image Velocimetry Method in the Presence of Strong Electric Fields

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1790
Author(s):  
Michal Malík ◽  
Jiří Primas ◽  
Petr Schovanec ◽  
Josef Novák ◽  
Pavel Pokorný ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Electric Fields ◽  
Particle Image ◽  
Negative Influence ◽  
Piv Method ◽  
Tracer Particles ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Measurement Results ◽  
Strong Electric Fields

While examining the airflow generated between the asymmetrical electrodes connected to high voltage, the authors investigated the possible limitations of the particle image velocimetry (PIV) method in the presence of strong electric fields. The tracer particles used in the PIV method in these conditions are affected by electromagnetic forces; therefore, it is necessary to determine whether these forces have any non-negligible negative influence on the measurement results. For this purpose, the authors theoretically analyzed all the possible forces and measured the generated airflow using PIV and constant temperature anemometry methods. The experimental and theoretical results clearly show the viability of the PIV measurement method even in these very specific conditions.

Flow Field Analysis of Dielectrophoretically-Suspended Particles

2007 ◽  
Author(s):  
Stuart J. Williams ◽  
Steven T. Wereley
Keyword(s):  
Electric Fields ◽  
Particle Image ◽  
Fluid Velocity ◽  
Microfluidic Channel ◽  
Velocity Fields ◽  
Field Analysis ◽  
Tracer Particles ◽  
Image Velocimetry ◽  
Flow Field Analysis ◽  
Complete Investigation

Understanding the fluid dynamics around a particle in suspension is important for a complete investigation of many hydrodynamic phenomena, including microfluidic models. A novel tool that has been used to analyze fluid velocity fields in microfluidics is micro-resolution particle image velocimetry (μPIV) [1]. Dielectrophoresis (DEP) is a technique that can translate and trap particles by induced polarization in the presence of nonuniform electric fields. In this paper, DEP has been used to capture and suspend a single 10.1μm diameter spherical particle in a microfluidic channel. μPIV is then used with smaller tracer particles (0.5μm) to investigate the hydrodynamics of fluid flow past the trapped particle.

Hydrodynamic Investigations of a Dielectrophoretically Trapped and Agitated Microparticle

2009 ◽  
Author(s):  
Stuart J. Williams ◽  
Steven T. Wereley
Keyword(s):  
Fluid Dynamics ◽  
Particle Image Velocimetry ◽  
Spherical Particle ◽  
Electric Fields ◽  
Particle Image ◽  
Suspended Particle ◽  
Microfluidic Channel ◽  
Induced Polarization ◽  
Image Velocimetry ◽  
Complete Investigation

Understanding the fluid dynamics of a particle in suspension is important for a complete investigation of many hydrodynamic phenomena, including microfluidic models. Dielectrophoresis (DEP) is a technique that can translate and trap particles through induced polarization when in the presence of non-uniform electric fields. Here, DEP has been used to capture and suspend a single 10.1 μm diameter spherical particle in a microfluidic channel. Procedures and results for controlled, oscillatory dielectrophoretic agitation of the suspended particle are shown. Hydrodynamic investigations are discussed including the incorporation of micron-resolution particle image velocimetry (μPIV).

scholarly journals Bemerkungen zur "kalten Fusion"

2019 ◽  
Author(s):  
Rainer Kühne
Keyword(s):  
Electric Fields ◽  
Heavy Water ◽  
Room Temperature ◽  
Nuclear Fusion ◽  
Cold Fusion ◽  
Theoretical Description ◽  
Long Time ◽  
Strong Electric Fields

Steven Jones et al. reported to have observed nuclear fusion at room temperature. They observed this "cold fusion" by electrolyzing heavy water. Later experiments confirmed these observations. These experiments confirmed the generation of strong electric fields within the deuterided metals. These electric fields accelerate the deuterons to keV energies and allow the observed nuclear fusion. Roman Sioda and I suggested a theoretical description of this nuclear fusion. Our "extended micro hot fusion" scenario explains how nuclear fusion can be generated over a long time within deuterided metals. Moreover we predicted the explosion of large pieces of deuterided metals. This article reviews the "cold fusion" work of Steven Jones et al. and discusses the fracto-fusion scenario. I show that the extended micro hot fusion scenario can explain the observed neutron emissions, neutron bursts, and heat bursts.

Flow visualization and mechanisms of three-electrode sliding discharge plasma actuator

2019 ◽  
Vol 233 (13) ◽  
pp. 4788-4799
Author(s):  
Borui Zheng ◽  
Jie Chen ◽  
Chang Ge ◽  
Xizheng Ke ◽  
Hua Liang
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Discharge Plasma ◽  
Plasma Actuator ◽  
Half Cycle ◽  
Continuous Mode ◽  
Dc Voltage ◽  
Image Velocimetry ◽  
Induced Velocity ◽  
Sliding Discharge

The unsteady flow characteristics induced by a three-electrode sliding discharge plasma actuator under different actuation modes were analyzed by ensemble averaged and phase-locked particle image velocimetry. The discharge morphologies, voltage–current waveforms, and particle image velocimetry data in continuous mode were compared to clarify the performance modification mechanism of the pulsed three-electrode sliding discharge. The particle image velocimetry results revealed that deformation of the electromagnetic field around the additional electrode caused by applying a high DC voltage triggers changes in the induced flow field. When the three-electrode sliding discharge plasma actuator is actuated in continuous mode, a strong accelerated wall jet and homogeneous discharge region covering the whole gap between the two exposed electrodes are generated. The large discharge extension mainly results from the accelerated drift of positive ion particles created during the positive half cycle, while negatively ionized particles have a significantly larger impact on the induced velocity production process. In the pulsed mode, when a positive high DC voltage ( VDC = 18 kV) is applied to the additional electrode, both the size and magnitude of the induced vortex structures increase, and highly accelerated regions are periodically generated. When V DC = −18 kV, the induced velocity field evens out, the accelerated region becomes less obvious, the intensity of both the primary and secondary vortices decreases, and the vortex structure dissipates faster, owing to the turbulent motion of ionized particles. An additional positive DC component attracts the negatively ionized particles during the negative half cycle, improving the velocity and intensity of the stream-wise vortices, which is very attractive for flow control applications.

scholarly journals Observed Enhancement of Reflectivity and the Electric Field in Long-Lived Florida Anvils

2007 ◽  
Vol 135 (10) ◽  
pp. 3362-3380 ◽  
Author(s):  
James E. Dye ◽  
John C. Willett
Keyword(s):  
Electric Fields ◽  
Charge Separation ◽  
Particle Interactions ◽  
Particle Collisions ◽  
Ice Particles ◽  
Particle Spectra ◽  
Strong Electric Fields ◽  
The Many ◽  
Convective Cells ◽  
Inductive Mechanism

Abstract A study of two long-lived Florida anvils showed that reflectivity >20 dBZ increased in area, thickness, and sometimes magnitude at the midlevel well downstream of the convective cores. In these same regions electric fields maintained strengths >10 kV m−1 for many tens of minutes and became quite uniform over tens of kilometers. Millimetric aggregates persisted at 9–10 km for extended times and distances. Aggregation of ice particles enhanced by the strong electric fields might have contributed to reflectivity growth in the early anvil, but is unlikely to explain observations farther out in the anvil. The enhanced reflectivity and existence of small, medium, and large ice particles far out into the anvil suggest that an updraft was acting, perhaps in weak convective cells formed by instability generated from the evaporation and melting of falling ice particles. It is concluded that charge separation must have occurred in these anvils, perhaps at the melting level but also at higher altitudes, in order to maintain fields >10 kV m−1 at 9–10 km for extended periods of time over large distances. The authors speculate that charge separation occurred as a result of ice–ice particle collisions (without supercooled water being present) via either a noninductive or perhaps even an inductive mechanism, given the observed broad ice particle spectra, the strong preexisting electric fields, and the many tens of minutes available for particle interactions. The observations, particularly in the early anvil, show that the charge structure in these anvils was quite complex.

scholarly journals Shrinking instability of toroidal droplets

2017 ◽  
Vol 114 (11) ◽  
pp. 2871-2875 ◽  
Author(s):  
Alexandros A. Fragkopoulos ◽  
Ekapop Pairam ◽  
Eric Berger ◽  
Phil N. Segre ◽  
Alberto Fernández-Nieves
Keyword(s):  
Surface Tension ◽  
Particle Image Velocimetry ◽  
Flow Field ◽  
Cross Section ◽  
Particle Image ◽  
Internal Flow ◽  
Experimental Results ◽  
Image Velocimetry ◽  
The Many

Toroidal droplets are inherently unstable due to surface tension. They can break up, similar to cylindrical jets, but also exhibit a shrinking instability, which is inherent to the toroidal shape. We investigate the evolution of shrinking toroidal droplets using particle image velocimetry. We obtain the flow field inside the droplets and show that as the torus evolves, its cross-section significantly deviates from circular. We then use the experimentally obtained velocities at the torus interface to theoretically reconstruct the internal flow field. Our calculation correctly describes the experimental results and elucidates the role of those modes that, among the many possible ones, are required to capture all of the relevant experimental features.

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