Wall Normal Jet Produced by DBD Plasma Actuator With Doughnut-Shaped Electrode

2008 ◽  
Author(s):  
Takehiko Segawa ◽  
Hiro Yoshida ◽  
Shinya Takekawa ◽  
Timothy Jukes ◽  
Kwing-So Choi
Keyword(s):  
Atmospheric Pressure ◽  
Room Temperature ◽  
Particle Image ◽  
Barrier Discharge ◽  
Plasma Actuator ◽  
Dbd Plasma ◽  
Annular Jet ◽  
Image Velocimetry ◽  
Inner Diameter ◽  
Annular Jets

Properties of coaxial annular jets produced by a dielectric barrier discharge (DBD) plasma actuator with a doughnut shaped electrodes were investigated under atmospheric pressure and room temperature. The actuator consists of two circular electrodes sandwiching a thin dielectric layer. By applying 0 – ±3.3 kV between the electrodes at radio frequencies, the plasma jet is formed near the inner edge of the top electrode. The radial jet runs toward the center of the electrode and then impinges at the center to generate a wall normal annular jet. The evolution of the wall normal jet was observed precisely using particle image velocimetry (PIV) system. It was found that characteristic velocities increase in proportion to the bursting frequency and inversely proportional to the inner diameter of the electrode at the surging time of the voltage at 5.0 × 10−6sec.

scholarly journals The starting vortex in quiescent air induced by dielectric-barrier-discharge plasma

2012 ◽  
Vol 703 ◽  
pp. 192-203 ◽  
Author(s):  
Richard D. Whalley ◽  
Kwing-So Choi
Keyword(s):  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Maximum Velocity ◽  
Plasma Actuator ◽  
Dbd Plasma ◽  
Dielectric Barrier ◽  
Image Velocimetry ◽  
Barrier Discharge Plasma ◽  
Self Similar ◽  
Surrounding Fluid

AbstractThe flow field around an asymmetric dielectric-barrier-discharge (DBD) plasma actuator in quiescent air is studied using particle image velocimetry (PIV) and smoke-flow visualization. On initiation of DBD plasma a starting vortex is created, which rolls up to form a coherent structure. The starting vortex becomes self-similar when the maximum velocity induced by the DBD plasma actuator reaches a steady state. Here, the plasma jet momentum increases linearly with time, suggesting that the DBD plasma actuator entrains and accelerates the surrounding fluid with a constant force. The wall-parallel and wall-normal distances of the vortex core are observed to scale with ${t}^{2/ 3} $ as it travels at $3{1}^{\circ } $ to the wall. The velocity of the starting vortex is found to scale with ${t}^{- 1/ 3} $, while the circulation induced by the plasma actuator scales with ${t}^{1/ 3} $.

scholarly journals Coherent structures induced by dielectric barrier discharge plasma actuator

2017 ◽  
Vol 31 (32) ◽  
pp. 1850038 ◽  
Author(s):  
Xin Zhang ◽  
Huaxing Li ◽  
Kwing So Choi ◽  
Longfei Song
Keyword(s):  
Flow Control ◽  
Dielectric Barrier Discharge ◽  
Coherent Structures ◽  
High Speed ◽  
Barrier Discharge ◽  
Plasma Actuator ◽  
Dbd Plasma ◽  
Peak Voltage ◽  
Dielectric Barrier ◽  
Piv Measurement

The structures of a flow field induced by a plasma actuator were investigated experimentally in quiescent air using high-speed Particle Image Velocimetry (PIV) technology. The motivation behind was to figure out the flow control mechanism of the plasma technique. A symmetrical Dielectric Barrier Discharge (DBD) plasma actuator was mounted on the suction side of the SC (2)-0714 supercritical airfoil. The results demonstrated that the plasma jet had some coherent structures in the separated shear layer and these structures were linked to a dominant frequency of [Formula: see text] = 39 Hz when the peak-to-peak voltage of plasma actuator was 9.8 kV. The high speed PIV measurement of the induced airflow suggested that the plasma actuator could excite the flow instabilities which lead to production of the roll-up vortex. Analysis of transient results indicated that the roll-up vortices had the process of formation, movement, merging and breakdown. This could promote the entrainment effect of plasma actuator between the outside airflow and boundary layer flow, which is very important for flow control applications.

Investigation of Combustion Oscillations in a Lean Gas Turbine Model Combustor

2007 ◽  
Author(s):  
Olaf Diers ◽  
Denis Schneider ◽  
Melanie Voges ◽  
Peter Weigand ◽  
Christoph Hassa
Keyword(s):  
Atmospheric Pressure ◽  
Acoustic Pressure ◽  
Particle Image ◽  
Operating Conditions ◽  
Operating Point ◽  
Image Velocimetry ◽  
Different Types ◽  
Mass Flows ◽  
Combined Data

This contribution is a continuation of ASME-GT2006-90300. While still working at atmospheric pressure, the range of operating conditions was extended to more realistic reduced mass flows to reproduce the engine pressure loss and air preheat up to 700K. The thermoacoustic behaviour of the burner was mapped over that operating range. Two different types of oscillations were observed for flames anchored at the nozzle or lifted from it. Both exhibited a frequency dependence on the Strouhal number for constant reduced mass flows. For a selected operating point with the lifted flame at a preheat temperature of 600K and a reduced mass flow of 0.3kg K0.5/(s bar), the thermoacoustic behaviour of the burner was characterised by phase locked Particle Image Velocimetry as well as phase locked OH- and OH-T- LIF measurements and correlated to the acoustic pressure signal obtained by microphones. The combined data showed pulsating combustion being supported through periodic reignition of the main flame zone by a recirculating volume of hot, OH-rich gas, the cycle time being connected to the observed frequency. The characterization of the preheated operating point was completed with a heat balance investigation quantifying the non-adiabatic combustion conditions of the uncooled combustor.

Parametric Survey for Efficient DeNOx by Direct Decomposition of NO Using an Intermittent DBD Generated by a One-Cycle Sinusoidal Power Source

2007 ◽  
Vol 10 (2) ◽  
Author(s):  
Ken Yukimura ◽  
Hiroshi Murakami ◽  
Masayuki Itoh
Keyword(s):  
Gas Flow ◽  
Room Temperature ◽  
Barrier Discharge ◽  
Electrical Power ◽  
Power Source ◽  
Injection System ◽  
Gas Flows ◽  
Mixing Zone ◽  
Dbd Plasma ◽  
Decomposition Of No

AbstractNO gas is directly decomposed using an intermittent DBD plasma generated by a one cycle sinusoidal power source. Previously, we have developed an ammonia radical injection system, where ammonia radicals were produced by a dielectric barrier discharge (DBD) in a chamber, called a radical injector, which is separate from the chamber in which NO gas flows. The radicals are injected into the mixing zone in the NO gas flow field to decompose NO gas. The power source for generating the DBD is a one-cycle sinusoidal (OCS) waveform so as to easily control the electrical power consumed in the DBD plasma. The fundamental frequency of the OCS power source is 150 kHz. In this paper, we used the same power source, but NO was decomposed directly by the plasma; that is, NO gas is in the DBD plasma. NO gas was varied from room temperature to approximately 400 C, where the effect of DeNOx characteristics were discussed. By optimizing parameters for DeNOx, an energy efficiency of 100 g/kWh was obtained.

Flow Control on a Transport Truck Side Mirror Using Plasma Actuators

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Theodoros Michelis ◽  
Marios Kotsonis
Keyword(s):  
Flow Control ◽  
Guide Vane ◽  
Leading Edge ◽  
Plasma Actuator ◽  
Plasma Actuators ◽  
Dbd Plasma ◽  
Reference Case ◽  
Image Velocimetry ◽  
Wind Tunnel Study ◽  
Edge Separation

A wind tunnel study is conducted toward hybrid flow control of a full scale transport truck side mirror at ReD=3.2×105. A slim guide vane is employed for redirecting high-momentum flow toward the mirror wake region. Leading edge separation from the guide vane is reduced or eliminated by means of an alternating current -dielectric barrier discharge (AC-DBD) plasma actuator. Particle image velocimetry (PIV) measurements are performed at a range of velocities from 15 to 25 m/s and from windward to leeward angles from -5deg to 5deg. Time-averaged velocity fields are obtained at the center of the mirror for three scenarios: (a) reference case lacking any control elements, (b) guide vane only, and (c) combination of the guide vane and the AC-DBD plasma actuator. The comparison of cases demonstrates that at 25 m/s windward conditions (-5deg) the guide vane is capable of recovering 17% momentum with respect to the reference case. No significant change is observed by activating the AC-DBD plasma actuator. In contrast, at leeward conditions (5deg), the guide vane results in a −20% momentum loss that is rectified to a 6% recovery with actuation. The above implies that for a truck with two mirrors, 23% of momentum may be recovered.

Surface Modification of Polypropylene Melt Blown Non-Woven Using Atmospheric Pressure Dielectric Barrier Discharge Plasma

2010 ◽  
Vol 42 ◽  
pp. 228-231 ◽  
Author(s):  
Yan Zhang ◽  
Yin Ding Lv
Keyword(s):  
Dielectric Barrier Discharge ◽  
Atmospheric Pressure ◽  
Barrier Discharge ◽  
Treatment Time ◽  
Woven Fabric ◽  
Dbd Plasma ◽  
Water Contact ◽  
Dielectric Barrier ◽  
Barrier Discharge Plasma ◽  
Plasma Treatment Time

In this paper, polypropylene (PP) melt blown non-woven fabric is treated by atmospheric pressure N2 or N2/CO2 dielectric barrier discharge (DBD) plasma. The variation of the surface hydrophilicity of PP sample is experimentally investigated by surface water contact angle, Fourier transform infrared reflectance spectroscopy (FTIR-ATR). The results show that the hydrophilicity of PP sample is considerably improved as long as the very short plasma treatment time (several seconds). However, the treatment effect of atmospheric N2/CO2 plasma is worse than that of atmospheric N2 plasma.

scholarly journals INHIBITION OF CANDIDA ALBICANS GROWTH ON SURFACES TREATED BY DIELECTRIC BARRIER DISCHARGE WITH VARIOUS BARRIERS

2014 ◽  
Vol 54 (4) ◽  
pp. 290-294 ◽  
Author(s):  
Jan Sláma ◽  
Vítezslav Kríha
Keyword(s):  
Candida Albicans ◽  
Dielectric Barrier Discharge ◽  
Atmospheric Pressure ◽  
Barrier Discharge ◽  
Low Temperature Plasma ◽  
Dbd Plasma ◽  
Barrier Material ◽  
Temperature Plasma ◽  
Dielectric Barrier ◽  
Non Destructive

Discharges generating low temperature plasma at atmospheric pressure have the potential to treat surfaces biologically contaminated by organic matter in a non-destructive manner. We have been studying ways of inhibiting the growth of microorganisms with the use of dielectric barrier discharge (DBD) plasma. The effect of the choice of a barrier material and its thickness on the<br />germicide properties of the DBD is described. We used Saboraud agar inoculated by 10<sup>5</sup> cfu/cm<sup>2</sup> of <em>Candida albicans</em> yeast as the model contaminated surface. After cultivation, the proportion of the treated surface with no <em>C. albicans</em> colony was evaluated.

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