Pulsed Plasma Actuators Research Articles

Electrical and Flow Characteristics of a Double-Side Sliding Pulsed Discharge Plasma Actuator

The development of next-generation high-maneuverability aircraft requires new technologies for controlling asymmetric separated vortices at high angles of attack. Plasma flow control is an emerging type of active flow control technology that can be used to control asymmetric vortices over slender bodies by means of pulsed dielectric barrier discharge (DBD) plasma actuators. However, some problems worthy of further study remain unsolved. For example, the stimulation strength is inadequate, the region of discharge is small, and the control mechanism is unclear. This paper proposes a double-side sliding pulsed discharge (DSPD) plasma actuator that combines a sinusoidal alternating current (AC) pulsed plasma actuator with two high-voltage direct current (DC) components. This actuator can generate two groups of unsymmetrical large-scale coherent vortex structures to balance the vorticity of the asymmetric vortices over the slender forebody of an aircraft and increase the distance between the cores of the asymmetric vortices, weakening the interaction between the vortices and hindering the emergence of the asymmetric phenomenon. Focusing on the key scientific issue of DSPD plasma actuation, the discharge morphologies and electrical properties under different DC conditions are studied, and the unsteady vortex structures induced by the DSPD plasma actuator under a static atmosphere are revealed through high-speed schlieren system and particle image velocimetry (PIV) measurements. The flow control ability of the DSPD plasma actuator is verified through wind tunnel experiments, and the main rules governing its influence on the external flowfield are determined. It is speculated that this actuator will further improve the aerodynamic flow control of slender aircraft.

Dynamic Stall of a Vertical-Axis Wind Turbine and Its Control Using Plasma Actuation

In this paper, a dynamic stall control scheme for vertical-axis wind turbine (VAWT) based on pulsed dielectric-barrier-discharge (DBD) plasma actuation is proposed using computational fluid dynamics (CFD). The trend of the wind turbine power coefficient with the tip speed ratio is verified, and the numerical simulation can describe the typical dynamic stall process of the H-type VAWT. The tangential force coefficient and vorticity contours of the blade are compared, and the regular pattern of the VAWT dynamic stall under different tip speed ratios is obtained. Based on the understanding the dynamic stall phenomenon in flow field, the effect of the azimuth of the plasma actuation on the VAWT power is studied. The results show that the azimuth interval of the dynamic stall is approximately 60° or 80° by the different tip speed ratio. The pulsed plasma actuation can suppress dynamic stall. The actuation is optimally applied for the azimuthal position of 60° to 120°.

A Numerical RANS‐Based Model of a Nanosecond Pulsed Plasma Actuator for Flow Control over an Airfoil

AbstractAirfoil stall influences the performance of flight vehicles and remains a challenge for the design of modern aircraft. A Dielectric Barrier Discharge (DBD) device seems to be a promising tool to control the flow over various parts of an aircraft and to suppress separation. A phenomenological model based on dynamic similarity is developed to simulate the control effect of a Nanosecond Dielectric Barrier Discharge (NS‐DBD) actuator. A two‐dimensional numerical simulation considers the response of the flow past a NACA 0015 airfoil at 14° post stall angle of attack and a Reynolds number of 250,000 to pulsed surface heating at the leading edge. The RANS‐based numerical results have been obtained for a baseline simulation (no actuation) and an open‐loop control simulation of the airfoil. A one‐equation local correlation‐based transition model is implemented to capture laminar‐turbulent transition. The numerical results of both the baseline and the actuated case are in good agreement with experiments performed by other authors.

Atmospheric-pressure pulsed plasma actuators for flow control: shock wave and vortex characteristics

Pulsed plasma actuators are used for an active flow control application since the 2000s. In this paper, we discuss shock wave and vortex characteristics in pulsed plasma actuators after an introduction of research progress on atmospheric-pressure discharge plasma actuators. First, the shock wave characteristics in surface dielectric barrier discharge (SDBD) actuator operating in diffuse-like and multi-streamer modes are discussed. In the most general case, a shock wave in a diffuse-like SDBD actuator is stronger and faster than in a multi-streamer SDBD actuator. Improved plasma actuators, such as the three-electrode SDBD actuator and the plasma synthetic jet actuator have the enhanced shock wave characteristics. Second, in order to investigate the effects of pulse parameters on the shock wave characteristics in nanosecond-pulse SDBD actuator, a particle image velocimetry system is used to capture the formation of starting vortexes at different pulse rise times, pulse durations, and pulse repetition frequencies (PRFs). It is shown that the velocity of a starting vortex significantly increases when the pulse rise time decreases from 400 ns to 50 ns due to a more significant hydrodynamic effect generated during a shorter rise time. This phenomenon is confirmed by calculating a reduced electric field E/N at a short rise time, which turns out to be higher at a shorter rise time than that at a relatively longer rise time. It is also shown that the velocity of a starting vortex increases and its active area enlarges when the PRF increases.

Numerical investigation of nanosecond pulsed plasma actuators for control of shock-wave/boundary-layer separation

This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced boundary-layer separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: boundary layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the boundary-layer separation stronger, while the canted electrode produced vorticity and suppressed the boundary-layer separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/boundary-layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/boundary-layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the boundary layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the boundary layer and, consequently, mitigating the shock induced boundary layer separation.

On the boundary flow using pulsed nanosecond DBD plasma actuators

Our previous studies in quiescent air environment [Z. J. Zhao et al., AIAA J. 53(5) (2015) 1336; J. G. Zheng et al., Phys. Fluids 26(3) (2014) 036102] reveal experimentally and numerically that the shock wave generated by the nanosecond pulsed plasma is fundamentally a microblast wave. The shock-induced burst perturbations (overpressure and induced velocity) are found to be restricted to a very narrow region (about 1 mm) behind the shock front and last only for a few microseconds. These results indicate that the pulsed nanosecond dielectric barrier discharge (DBD) plasma actuator has stronger local effects in time and spatial domain. In this paper, we further investigate the effects of pulsed plasma on the boundary layer flow over a flat plate. The present investigation reveals that the nanosecond pulsed plasma actuator generates intense perturbations and tends to promote the laminar boundary over a flat plate to turbulent flow. The heat effect after the pulsed plasma discharge was observed in the external flow, lasting a few milliseconds for a single pulse and reaching a quasi-stable state for multi-pulses.

A note on supersonic flow control with nanosecond plasma actuator

A concept study on supersonic flow control using nanosecond pulsed plasma actuator is conducted by means of numerical simulation. The nanosecond plasma discharge is characterized by the generation of a micro-shock wave in ambient air and a residual heat in the discharge volume arising from the rapid heating of near-surface gas by the quick discharge. The residual heat has been found to be essential for the flow separation control over aerodynamic bodies like airfoil and backward-facing step. In this study, novel experiment is designed to utilize the other flow feature from discharge, i.e., instant shock wave, to control supersonic flow through shock-shock interaction. Both bow shock in front of a blunt body and attached shock anchored at the tip of supersonic projectile are manipulated via the discharged-induced shock wave in an appropriate manner. It is observed that drag on the blunt body is reduced appreciably. Meanwhile, a lateral force on sharp-edged projectile is produced, which can steer the body and give it an effective angle of attack. This opens a promising possibility for extending the applicability of this flow control technique in supersonic flow regime.

Parametric Study of Paraelectric and Peristaltic Pulsed DBD Plasma Actuation for Aerodynamic Flow Control Based on PIV

Using single and multiple dielectric barrier discharge plasma actuators, the velocity fields induced by steady, pulsed, asynchronous, and duty cycle plasma actuation are studied based on Particle Image Velocimetry (PIV). First, the flow fields induced by a single dielectric barrier discharge with different discharge models and actuation parameters are investigated. According to the velocity distributions, a parametric study on the influence of excitation voltages, carrier frequencies, pulse frequencies, and duty ratios on plasma actuation is presented and the optimum actuation parameters are provided. Emphatically, through double actuators alternating discharge, the peristaltic acceleration plasma actuation, a new plasma actuation mode, has been proposed and studied. The efficiency of the plasma actuators in steady and pulsed discharge modes is explored. The velocity field induced by plasma actuation with different phase angles and duty cycle ratios is acquired and the momentum transfer characteristics of the flow field were discussed. Finally, based on the above-mentioned results, the technical superiority and mechanism of the peristaltic acceleration induced by multiple dielectric barrier discharge plasma actuators are analyzed.

Nanosecond-Pulsed Dielectric Barrier Discharge Plasma Actuator for Airflow Control Along an NACA0015 Airfoil at High Reynolds Number

The goal of the present experimental study is to investigate the ability of a surface nanosecond pulsed dielectric barrier discharge plasma actuator, located at the leading edge of the airfoil, to delay flow separation along the suction side of an NACA0015 airfoil inclined at 13.5°, using a particle image velocimetry system. The free-stream velocity is equal to U <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> = 40 m/s, giving a chord-based Reynolds number of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ec</sub> = 1.33×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> . At such conditions, the baseline flow separation occurs at about 50% of chord. On the one hand, the results show that the separation location moves progressively toward the trailing edge when the high-voltage frequency Fpulse is increased, up to 85% of chord at 1630 Hz (reduced frequency F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pulse</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> = 10.6), which is due to the increase of the injected electrical power with F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pulse</sub> (from 8 mW/cm at 40 Hz to 290 mW/cm at 1630 Hz). On the other hand, the use of a burst-modulated actuation (with a constant electrical power consumption equal to 145 mW/cm) does not produce the same behavior. At the lowest and highest frequencies (16 and 408 Hz, corresponding to the reduced frequencies of 0.1 and 2.65, respectively), the separation is delayed to about 60% of chord, while the most effective actuation is observed at F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">burst</sub> = 80 Hz (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">burst</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> = 0.53) with a separation delaying to 83% of chord.

Induced Velocity and Density Gradients due to Nanosecond Plasma Actuation

An experimental and numerical investigation is presented on the effects due to the energy deposition induced by a nanosecond pulsed dielectric barrier discharge plasma actuator on a flat-plate boundary layer. High magnification rate particle image velocimetry was used in a phase-locked arrangement to resolve the velocity field after actuation. The parameters investigated were the orientation of the actuator with respect to the flow direction and the energy input. The backcurrent shunt technique was employed to monitor the high-voltage pulse and to calculate the energy input. Results indicate that effects induced by this type of plasma actuator are strongly dependent on the orientation of the actuator with respect to the direction of the flow. When the covered high-voltage electrode is in the upstream position, a region of decelerated flow is observed in the vicinity of the actuator. On the other hand, when the covered high-voltage electrode is in downstream position, a region of accelerated flow is observed, highlighting the presence of a weak directional body force in addition to the thermal energy deposition typically associated with nanosecond plasma actuation. The thermal energy deposition is responsible for considerable density gradients, which are calculated using the compressible continuity equation on the measured velocity fields. Calculations show good qualitative agreement with experimental schlieren imaging. In general, nanosecond pulsed dielectric barrier discharge plasma actuators appear to induce a combination of thermal effects manifested as density/viscosity gradients and momentum effects manifested as weak directional body forces.

Numerical Simulation of Combustion Enhancement Through a Repetitive Pulsed Plasma Actuator

This work presents a numerical study of combustion enhancement using a repetitive pulsed plasma actuator. A large-eddy simulation turbulence model is considered to investigate the nonpremixed turbulent combustion of methane-air flow. The baseline case shows agreement with published numerical data. Based on recent studies, it is assumed that the repetitive pulsed actuators are able to create acoustic perturbations for flow control. Numerical results show that induced acoustic perturbations may enhance chemical reactions and result in modification of the flame shape. These numerical results may be useful for the design and improvement of a coaxial jet combustor.

Flow separation control on swept wing with nanosecond pulse driven DBD plasma actuators

A 15° swept wing with dielectric barrier discharge plasma actuator is designed. Experimental study of flow separation control with nanosecond pulsed plasma actuation is performed at flow velocity up to 40m/s. The effects of the actuation frequency and voltage on the aerodynamic performance of the swept wing are evaluated by the balanced force and pressure measurements in the wind tunnel. At last, the performances on separation flow control of the three types of actuators with plane and saw-toothed exposed electrodes are compared. The optimal actuation frequency for the flow separation control on the swept wing is detected, namely the reduced frequency is 0.775, which is different from 2-D airfoil separation control. There exists a threshold voltage for the low swept wing flow control. Before the threshold voltage, as the actuation voltage increases, the control effects become better. The maximum lift is increased by 23.1% with the drag decreased by 22.4% at 14°, compared with the base line. However, the best effects are obtained on actuator with plane exposed electrode in the low-speed experiment and the abilities of saw-toothed actuators are expected to be verified under high-speed conditions.

Aerodynamic performance enhancement of a flying wing using nanosecond pulsed DBD plasma actuator

Experimental investigation of aerodynamic control on a 35° swept flying wing by means of nanosecond dielectric barrier discharge (NS-DBD) plasma was carried out at subsonic flow speed of 20–40m/s, corresponding to Reynolds number of 3.1×105–6.2×105. In control condition, the plasma actuator was installed symmetrically on the leading edge of the wing. Lift coefficient, drag coefficient, lift-to-drag ratio and pitching moment coefficient were tested with and without control for a range of angles of attack. The tested results indicate that an increase of 14.5% in maximum lift coefficient, a decrease of 34.2% in drag coefficient, an increase of 22.4% in maximum lift-to-drag ratio and an increase of 2° at stall angle of attack could be achieved compared with the baseline case. The effects of pulsed frequency, amplitude and chord Reynolds number were also investigated. And the results revealed that control efficiency demonstrated strong dependence on pulsed frequency. Moreover, the results of pitching moment coefficient indicated that the breakdown of leading edge vortices could be delayed by plasma actuator at low pulsed frequencies.

1203 間欠駆動プラズマアクチュエータを用いたブラフボディ剥離制御流れ場の時系列PIV解析(流体工学II)

1203 間欠駆動プラズマアクチュエータを用いたブラフボディ剥離制御流れ場の時系列PIV解析(流体工学II)

S0530303 プラズマアクチュエータのバースト周波数変化がNACA0012翼面上の流れ場と空力特性に与える影響

S0530303 プラズマアクチュエータのバースト周波数変化がNACA0012翼面上の流れ場と空力特性に与える影響

Experimental study of flow control on delta wings with different sweep angles using pulsed nanosecond DBD plasma actuators

A low-speed wind tunnel study of active flow control for improving aerodynamic performance of delta wings at high angles of attack is presented. A dielectric barrier discharge actuator driven by pulsed nanosecond voltage is used to create periodic perturbations along the leading edge of delta wing. Four wings with sweep back angles of Λ = 30°, 47°, and 60° are tested. Data obtained by means of force measurements show that the effectiveness of the actuation strongly depends on the wing’s sweep angles and the actuation frequency. For Λ = 30°, 47° delta wings, the pulsed actuation could increase the lift at post stall regions. For Λ = 60° delta wing, the pulsed actuation at the leading edge almost has no effect on its aerodynamic performance. At last, the control mechanism is discussed.

Plasma-based feed-forward dynamic stall control on a vertical axis wind turbine

Dynamic stall was controlled on a double-bladed H-Rotor vertical axis wind turbine model using pulsed dielectric barrier discharge plasma actuators in a feed-forward control configuration. The azimuthal angles of plasma actuation initiation and termination, that produced the largest increases in power, were determined parametrically on the upstream half of the turbine azimuth in a low-speed blow-down wind tunnel at wind speeds of 7m/s. A mathematical model, together with instantaneous turbine speed, was used to estimate transient torque and power developed by the turbine under the influence of plasma actuation. Overall performance improvements were based on changes between the final actuated and initial baseline results. A remarkable result of this investigation was that a net turbine power increase of 10% was measured. This was achieved by systematically reducing plasma pulsation duty cycles as well as the plasma initiation and termination angles. Nevertheless, it was determined that further performance increases could be achieved by changing the actuator’s dielectric material, increasing the turbine radius and developing a method for control of dynamic stall on both the upwind (inboard of the blades) and downwind (outboard of the blades) halves of the turbine azimuth. Copyright © 2014 John Wiley & Sons, Ltd.

Wind-Energy Generation by Active Flow Control

This paper presents and tests a novel wind-energy generator that is driven by active flow control. To achieve this, flow-control-induced oscillations were forced by dynamic boundary layer separation and attachment using plasma actuators. Proof-of-concept wind tunnel experiments, at a subcritical Reynolds number of 80,000, were performed on a one-degree-of-freedom pivoted cylindrical body where pulsed dielectric barrier discharge plasma actuators were used to control separation. A nonlinear load, typical of a positive displacement fluid pump, was attached to the system and calibrated. Using phase-locked actuation, simultaneous pressure and angular displacement measurements were performed to determine the integrated mean system power. A system model, including non-linear load effects, aerodynamic effects and friction was developed. Peak measured power coefficients were relatively small, less than 1%; nevertheless the power required to drive the actuators was one order of magnitude lower than the measured sy...

Design and Application of Multichannel Peristaltic Acceleration Pulsed Plasma Power Supply

Based on the continuous and microsecond pulsed plasma power supply, a multichannel peristaltic acceleration pulsed plasma power supply is developed. The overall design ideas and system block diagram are proposed. Additional modulation functions of pulsed phase angle, duty cycle ratio, and pulsed frequency are implemented to improve the control capability of the plasma actuation for flow control. Long time running results show that this power supply can generate good waveform and smooth plasma discharge. It meets the requirements of plasma discharge for various means of flow control, such as continuous, pulsed, duty cycle, and peristaltic acceleration plasma actuation. Finally, successful wind-tunnel experiments for plasma flow control over a slender body at high angle of attack by using this power supply is conducted. It shows that the plasma actuation excited by the power supply provides the highly needed lateral force and moment control on slender body at high angles of attack, without the unpredictable onset of asymmetric aerodynamic loads.

On the mechanism of bluff body flow control by pulsed plasma actuator

On the mechanism of bluff body flow control by pulsed plasma actuator