Optimization of Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Subatmospheric Pressures (original) (raw)
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Optimization of Dielectric Barrier Discharge Plasma Actuators Driven By Repetitive Nanosecond Pulses
2007
A detailed physical model for an asymmetric dielectric barrier discharge (DBD) in air driven by repetitive nanosecond voltage pulses is developed. In particular, modeling of DBD with high voltage repetitive negative and positive nanosecond pulses combined with positive dc bias is carried out. Operation at high voltage is compared with operation at low voltage, highlighting the advantage of high voltages,
38th Plasmadynamics and Lasers Conference, 2007
Experimental studies were conducted of a flow induced in an initially quiescent room air by a single asymmetric dielectric barrier discharge driven by voltage waveforms consisting of repetitive nanosecond high-voltage pulses superimposed on DC or alternating sinusoidal or square-wave bias voltage. To characterize the pulses and to optimize their matching to the plasma, a numerical code for short pulse calculations with an arbitrary impedance load was developed. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. This approach allowed us to restore the entire two-dimensional unsteady plasma induced flow pattern as well as characteristics of the plasma induced force. The experiments and computations showed vortex flow structures induced by the actuator. Parametric studies of the vortices at different bias voltages, pulse polarities, peak pulse voltages, and pulse repetition rates were conducted. The significance of charge build-up on the dielectric surface was demonstrated. Based on the observations, a new voltage waveform, consisting of high-voltage nanosecond repetitive pulses superimposed on a highvoltage low-frequency sinusoidal voltage, was proposed. Advantages of the new voltage waveform were demonstrated experimentally.
Modeling of dielectric barrier discharge plasma actuator
Journal of Applied Physics, 2008
Glow discharge at atmospheric pressure using a dielectric barrier discharge can induce fluid flow and operate as an actuator for flow control. In this paper, we simulate the physics of a two-dimensional asymmetric actuator operating in helium gas using a high-fidelity first-principles-based numerical modeling approach to help improve our understanding of the physical mechanisms associated with such actuators. Fundamentally, there are two processes in the two half-cycles of the actuator operation, largely due to the difference in mobility between faster electrons and slower ions, and the geometric configurations of the actuator ͑insulator and electrodes͒. The first half-cycle is characterized by the deposition of the slower ion species on the insulator surface while the second half-cycle by the deposition of the electrons at a faster rate. A power-law dependence on the voltage for the resulting force is observed, which indicates that larger force can be generated by increasing the amplitude. Furthermore, one can enhance the effectiveness of the actuator by either increasing the peak value of the periodic force generation or by increasing the asymmetry between the voltage half-cycles or both. Overall, the increase in the lower electrode size, applied voltage, and dielectric constant tends to contribute to the first factor, and the decrease in frequency of applied voltage tends to contribute to the second factor. However, the complex interplay between the above factors determines the actuator performance.
Energy and force prediction for a nanosecond pulsed dielectric barrier discharge actuator
Journal of Applied Physics, 2012
A three-species physical model is presented for dielectric barrier discharge (DBD) actuator under 8 atmospheric pressure. The governing equations are solved for temporal and spatial distribution of 9 electric potential and charge species using the finite element based multiscale ionized gas flow 10 code. The plasma model is loosely coupled with compressible Navier-Stokes equations through 11 momentum and energy source terms. Two cases of rf powered and nanosecond pulsed barrier 12 discharge actuators are simulated. Based on the imparted time average electrohydrodynamic force 13 and power deposition to the neutral gas, the nanosecond pulsed DBD actuator creates significant 14 pressure variations within few microseconds. These results are in reasonable agreement with 15 recently reported experimental shadow images. V
AIP Advances, 2021
In this study, experimental results presenting the development of Dielectric Barrier Discharge (DBD) powered by bipolar and unipolar pulses are compared. The experimental results showed that discharge current peaks in the case of DBD driven by repetitive unipolar pulses were about three times lower than those in the case of DBD driven by bipolar pulses. It is well known that if DBD is driven by bipolar pulses, the effect of surface charge on dielectric layers from the preceding discharge helps to ignite consecutive discharges at the same locations where the previous discharges already struck. In contrast, in the case of DBD generated by using the low-frequency unipolar pulses, the consecutive DBDs just could be initiated after the system erases part of the prehistory effect of surface charge deposition on dielectric layers from the preceding discharge, and then the following discharge was ignited at erased or uncharged areas. It was critical that a part of the energy stored in the dielectric layer and discharge gap by the previous discharge needed to be released to develop the next discharge. The results of this study provided an outlook for estimating the effectiveness of the DBD plasma system used in specific applications such as DBD for flow actuators or surface treatment where the use of unipolar DBDs at low frequency may be necessary.
Power consideration in the pulsed dielectric barrier discharge at atmospheric pressure
Journal of Applied Physics, 2004
Nonequilibrium, atmospheric pressure discharges are rapidly becoming an important technological component in material processing applications. Amongst their attractive features is the ability to achieve enhanced gas phase chemistry without the need for elevated gas temperatures. To further enhance the plasma chemistry, pulsed operation with pulse widths in the nanoseconds range has been suggested. We report on a specially designed, dielectric barrier discharge based diffuse pulsed discharge and its electrical characteristics. Two current pulses corresponding to two consecutive discharges are generated per voltage pulse. The second discharge, which occurs at the falling edge of the voltage pulse, is induced by the charges stored on the electrode dielectric during the initial discharge. Therefore, the power supplied to ignite the first discharge is partly stored to later ignite a second discharge when the applied voltage decays. This process ultimately leads to a much improved power transfer to the plasma.
Journal of Electrostatics, 2009
Dielectric barrier discharge (DBD) is an important method to produce non-thermal plasma, which has been widely used in many fields. In the paper, a repetitive nanosecond-pulse generator is used for the excitation of DBD. Output positive pulse of the generator has a rise time of about 15 ns and a full width at half maximum of 30-40 ns, and pulse repetition frequency varies from single shot to 2 kHz. The purpose of this paper is to experiment the electrical characteristics of DBD driven by repetitive nanosecond pulses. The variables affecting discharge conditions, including air gap spacing, dielectric thickness, barrier fashion, and applied pulse repetition frequency, are investigated. The relationship between electric field, discharge current, instantaneous discharge power across air gap, and estimated electron density with the length of air gap, dielectric thickness, barrier fashion, and pulse repetition frequency is obtained respectively, and the experimental results are also discussed. In addition, two typical images exhibiting homogeneous and filamentary discharges are given with different experimental conditions.
Physics of Plasmas, 2010
There has been much recent interest in boundary layer ͑BL͒ actuation by offset surface dielectric barrier discharges ͑SDBD͒. These discharges either act directly on the gas momentum through the mechanism of charge separation or they increase the flow stability through the creation of disturbances to the BL at a particular frequency. The objective of the work reported here is to clarify the physical mechanism of plasma-flow interaction. Two problems are considered in detail: the exact spatial/temporal distribution of the plasma-related force, and the specific role of negative ions in the net force budget. The experiments were made with an offset electrode configuration of SDBD at voltage amplitude U Յ 12 kV and frequency f = 0.02-2 kHz. The main data were obtained by time-resolved Pitot tube pressure measurements in air and nitrogen at atmospheric pressure. Three main features of SDBD behavior were considered. First, the strong inhomogeneity in the spatial distribution of the plasma-induced flow were detected. Second, the principal role of negative ions in plasma-induced flow generation was established. Third, the two types of gas disturbances were observed: the thermal effect and momentum transfer effect ͑ion wind͒. To explain the aforementioned features of SDBD behavior in air and nitrogen the results of numerical simulation have been used.
Studies on the configurations of nanosecond DBD pulse plasma actuators
2014
A conventional straight dielectric barrier discharge (DBD) actuator and a comb-shape DBD actuator driven by a high voltage nanosecond pulse were experimentally studied. The electric characteristics of the actuators were measured using a high voltage probe and a current shunt. The shock wave generated by the pulsed plasma was captured using a phaselocked Schlieren imaging technique. Different from the straight DBD actuator, the comb-shape DBD actuator shows a distinct formation of shock wave. These shock waves are generated from the plasma occurred only at the tips of the actuator. This implies that the layouts of the DBD actuators affect the electric potential between the exposed and covered electrodes, leading to various formations of shock wave. Thus different configurations of the nanosecond DBD actuators need to be considered when they are used for different applications in flow control.