Single-dielectric barrier discharge plasma actuator modelling and validation

In recent years, single dielectric barrier discharge (SDBD) plasma actuators have gained great interest among all the active flow control devices typically employed in aerospace and turbomachinery applications [1,2]. Compared with the macro SDBDs, the micro single dielectric barrier discharge (MSDBD) actuators showed a higher efficiency in conversion of input electrical power to delivered mechanical power [3,4]. This article provides data regarding the performances of a MSDBD plasma actuator [5,6]. The power dissipation values [5] and the experimental and numerical induced velocity fields [6] are provided. The present data support and enrich the research article entitled “Optimization of micro single dielectric barrier discharge plasma actuator models based on experimental velocity and body force fields” by Pescini et al. [6].

The effects of single dielectric barrier discharge plasma actuators on flow control are studied using a new frequency and pressure-dependent capacitance-based model by calculating the spatiotemporal distribution of surface charge density in the present work. The proposed model is an improvement over earlier similar efforts, but it retains the superior features of previous macroscopic models. It can be used to accurately compute the spatiotemporal distribution of body force due to plasma actuation without computing the complex electrodynamics equations for charge density on microscopic scales. It has been shown that the proposed model estimates the time-averaged total body force more accurately than similar models developed earlier, as compared to experimental results. The effects of plasma excitation frequency and the voltage waveform were considered. The proposed model has been incorporated into a Navier–Stokes equation solver in a time-accurate manner to study single dielectric barrier discharge plasma actuation in a quiescent flow environment. The onset of plasma actuation causes the creation of a complex transient vortical flowfield: one of its actions is to create a wall jet. Computed instantaneous velocity profiles at downstream locations show this wall jet, and they are compared with the experimental results. The computed results of the evolution of a starting vortex in a quiescent air induced by initiation of single dielectric barrier discharge plasma actuation display an excellent match with the experimental results of Whalley and Choi (“The Starting Vortex in Quiescent Air Induced by Dielectric-Barrier-Discharge Plasma,” Journal of Fluid Mechanics, Vol. 55, July 2012, pp. 192–203).

We have performed measurements of the force induced by both single (one electrode insulated) and double (both electrodes insulated) dielectric barrier discharge plasma actuators in quiescent air. We have shown that, for single barrier actuators with cylindrical exposed electrodes, as the electrode diameter decrease the force efficiencies increase much faster than a previously reported linear trend. This behavior has been experimentally verified using two different measurement techniques: stagnation probe measurements of the induced flow velocity and direct measurement of the force using an electronic balance. Actuators with rectangular cross-section exposed electrodes do not show the same rapid increase at small thicknesses. We have also shown that the induced force is independent of the material used for the exposed electrode. The same techniques have shown that the induced force of a double barrier actuator increases with decreasing narrow electrode diameter.

The aerodynamic flow acceleration with one atmosphere uniform induced single and multiple dielectric-barrier-discharge plasma actuation were studied based on PIV. Firstly, the flow fields induced by the single dielectric barrier discharge with different discharge models, and actuation parameters were investigated. In term of the obtained velocity distributions, a comparative study on the effect of excitation voltages, carrier frequencies, pulse frequencies and duty ratios on plasma actuation was presented and the optimum actuation parameters was provided. Moreover, through double actuators alternating discharge, the multiple dielectric barrier discharge mode have been proposed and tested. The efficiencies of the plasma actuators in Pulsed-pulsed, Steady-steady, Pulsed-steady and Steady-pulsed discharge modes were explored. Finally, based on the above results,the flow acceleration performance of single and multiple plasma actuators has been discussed and the more efficient discharge pattern has been proposed.The results of this study indicate: 1) The induced velocity increases linearly with excitation voltage and frequency. 2) When fp 300Hz, it shows an opposite tendency. 3) The airflow acceleration effect of multiple plasma actuators mainly occurs in paraelectric direction and the Pulsed-pulsed is the more efficient multiple plasma actuation mode.

A numerical investigation was carried out to assess the effectiveness of plasma-based flow control for a swept-wing configuration. A single dielectric barrier discharge plasma actuator was used to delay transition generated by excrescence near the leading edge. Large-eddy simulations were performed for the configuration, which had a wing airfoil section that is representative of modern reconnaissance air vehicles and maintained an appreciable region of laminar flow at design conditions. High-fidelity numerical solutions to the Navier–Stokes equations were generated for wing sweep angles of 30 and 45 deg and compared with the previously obtained unswept case. Control was generally more difficult to attain for nonzero sweep angles and transition could not be delayed for the 45 deg case unless a novel segmented swept actuator configuration was employed. Features of the computed flowfields are elucidated and effects of plasma actuation are quantified. It was found, for a sweep angle of 30 deg, that the wing lift-to-drag ratio could be increased by 9% by applying plasma control, which is comparable to that of the unswept situation. With a sweep angle of 45 deg, although plasma control could delay transition, the lift-to-drag ratio was not favorably altered.

The present study intends to investigate the potentiality of the single dielectric barrier discharge plasma actuators (SDBDPAs) to reattach the separated flow, occurring at low Reynolds numbers. For this aim, a curved wall plate, which profile shape was designed to reproduce the suction surface of a low-pressure turbine (LPT) blade, was installed in the test section of a closed loop wind tunnel and a SDBDPA was placed in a groove made over it, at the front of the adverse pressure gradient region. The flow behavior in absence of actuation has been experimentally investigated by particle image velocimetry (PIV) and laser Doppler velocimetry measurements (LDV). Moreover, sinusoidal voltage excitation with amplitude of 8 kV and frequency of 2 kHz was applied to the SDBDPA and PIV measurements were also performed in presence of actuation. The applied voltage and the discharge current have also been recorded simultaneously, and they have been used for the determination of the device dissipated power. Different wind tunnel free stream velocities were investigated, both in absence and presence of actuation. The effect of the active flow control was then studied in the entire measurement domain by analyzing the velocity fields, the turbulence intensity (Tu) values, the momentum coefficient (cμ) and the boundary layer shape factor (H12). In absence of actuation, a large reverse flow and a turbulence intensity up to ≈60% was observed in the separation region. Good agreement was found between the flow results obtained by the two velocity measurement techniques. Considering the actuated cases, it was found that, in all the tested operating conditions, actuation implied a reduction of the separated region and the turbulence intensity, even if a low flow control effect was noticed at the highest tested velocity.

Single dielectric barrier discharge plasma actuators were investigated for a range of static pressures from 0.17 to 9.0 bar. The actuatorminimum ionization voltage and static thrust weremeasured and similar data in the literature. The minimum ionization voltage decreased with decreasing pressure; however, at a given pressure, the ionization voltage scaled with the actuator capacitance per unit area. The static thrust was found to have a minimum at a pressure of approximately 2 bar. A narrow local maximum was found near 0.9 bar, below which the thrust decreased. A second broad local maximum occurred near 6 bar. The location of the two local maxima, respectively, moved to lower and higher pressures as the actuator voltage increased. At any pressure, thrust scaledwith voltage to a power. The power-law exponent increased linearly with increasing pressure from the lowest pressure tested to approximately 5 bar. Above 5 bar, the power-law exponent asymptotes to approximately 7.3, which was approximately twice that at atmospheric pressure. The experimental results were evaluated using a space–time lumped-element model for single dielectric barrier discharge plasma actuators. The overall trends were found to be best modeled through a pressure dependence of the minimum ionization voltage and the electron density.

This paper presents a computational assessment of the use of Single Dielectric Barrier Discharge (SDBD), or plasma, actuators for the suppression of short-length scale (spike) stall inception in a transonic axial compressor. Casing plasma actuation has the potential to provide a robust and effective stall suppression device without compromising compressor performance. The objective of this work is to determine the optimum actuator location and actuation strength needed to suppress spike stall inception at transonic speeds without imposing a penalty on compressor performance. This is done through the implementation of an actuator model in a turbomachinery CFD code for simulations of a transonic research compressor rotor passage to measure the effectiveness of casing plasma actuation in delaying the tip clearance flow criteria that are believed to lead to the formation of spike disturbances. Results show that the casing plasma actuator should be positioned near the rotor leading edge so as to optimize the impact on the interface between the incoming and tip clearance flows as well as for practical consideration. Simulations also indicate that the required actuator strength is higher than that of typical SDBD actuators while still remaining within practical achievable limits. These results will form the basis for experimental validation of the concept in the corresponding research compressor rig in the near future.

Summary form only given. Plasma actuators based on the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP/spl trade/) can be used to accelerate and reattach flows, increase the stall angle of airfoils, and modify the aerodynamic boundary layer of aircraft at the relatively low power cost of 5 to ten watts per linear foot of actuator. The characteristics and performance of OAUGD plasma actuators have been measured in the 7/spl times/11 Low Speed Wind Tunnel located at the NASA Langley Research Center. This wind tunnel was used to conduct drag measurements, smoke visualization studies, boundary layer velocity profile measurements, and flow attachment tests. This paper discusses two EHD (electrohydrodynamic) processes that utilize RF displacement currents to produce the body forces that accelerate the plasma: paraelectric and peristaltic (traveling wave) flow acceleration. Paraelectric flow acceleration results when the applied electric field acts on the net charge density of the plasma to provide a body force capable of accelerating the neutral gas to velocities up to 10 m/sec. During this process, the plasma moves paraelectrically towards increasing electric field gradients, and drags the neutral gas along with it as the result of frequent ion-neutral collisions. Peristaltic flow acceleration uses a polyphase power supply to energize successive OAUGDP/spl trade/ plasma actuators at progressive voltage phase angles. The resulting horizontal electric field of the traveling electrostatic wave produces a body force that accelerates the plasma, analogous to the apparent motion of light in a phased array of bulbs on a theatre marquee. A OAUGDP/spl trade/ plasma actuator intended for aerodynamic applications consists of electrodes flush mounted on either side of a dielectric panel. The panels are energized by a RF power supply that characteristically operates at voltages between 0 and 10 kV, and frequencies between 0.5 kHz and 8 kHz. During our plasma actuator development program, many electrode geometries were designed and investigated to obtain optimum operating conditions. Parametric dependencies from the flow visualization and velocity profile tests are presented for a wide range of operating conditions, and the need to establish an optimum operating condition is discussed.

Plasma actuators operating under atmospheric conditions show great promise for flow control due to their unique physical characteristics, such as the body force generated by a strong electric field. This study numerically examines the effect of low-powered plasma actuation on the aerodynamic performance of a NACA 2412 airfoil. Utilizing the Shyy plasma actuation model, the study simulates its effects through defined functions. The analysis investigates the lift and drag coefficients at various angles of attack, with a freestream velocity of 14.5 m/s. Without plasma actuation, the airfoil experiences common aerodynamic challenges, such as flow separation near the trailing edge, which reduces efficiency. However, plasma actuation accelerates the airflow over the upper surface, delaying flow separation and decreasing drag. This results in smoother airflow and increased lift, particularly at higher angles of attack. The use of plasma actuation achieved approximately a 21% increase in the lift coefficient. Overall, plasma actuators enhance airflow control, reduce drag, and boost lift, improving the airfoil’s aerodynamic performance. This improvement is supported by pressure contour analysis, which demonstrates a more favorable pressure distribution with plasma actuation.

The objective of current paper is 3D simulation of turbulent, developing flow and unsteady within a circular duct in presence of the body force vector persuaded by Dielectric barrier discharge (DBD) plasma actuator inside the surface of geometry for the first time. This article aims at investigating of applying plasma actuator to control separation with special arrangement of electrodes. For this reason, the plasma actuator is modeled in OpenFOAM software and the results are validated.Subesequently, to examine the effect of the presence of the plasma actuator a numerical study is carried out on a 3D flow. The physics of the problem is determined by three phenomena of increasing the flow cross-sectional, developing flow and simultaneous flow in both radial and tangential directions, especially the pressure gradients. As a result of the geometry of the problem, the actuators are arranged differently and the electrodes are arranged in radial direction. The results indicate that plasma actuator delay the separation point.

Mechanism of compressor airfoil boundary layer flow control using nanosecond plasma actuation

Numerical Investigation of Flow Separation Control on a Highly Loaded Compressor Cascade by Plasma Aerodynamic Actuation

A recently introduced phenomenological model to simulate flow control applications using plasma actuators has been further developed and improved in order to expand its use to complicated actuator geometries. The new modeling approach eliminates the requirement of an empirical charge density distribution shape by using the embedded electrode as a source for the charge density. The resulting model is validated against a flat plate experiment with quiescent environment. The modeling approach incorporates the effect of the plasma actuators on the external flow into Navier Stokes computations as a body force vector which is obtained as a product of the net charge density and the electric field. The model solves the Maxwell equation to obtain the electric field due to the applied AC voltage at the electrodes and an additional equation for the charge density distribution representing the plasma density. The new modeling approach solves the charge density equation in the computational domain assuming the embedded electrode as a source therefore automatically generating a charge density distribution on the surface exposed to the flow similar to that observed in the experiments without explicitly specifying an empirical distribution. The model is validated against a flat plate experiment with quiescent environment.

In order to apply plasma actuator to boundary layer transition control, it is necessary to introduce a body force into the appropriate part of the boundary layer, especially near the wall surface. To develop a device that can introduce body force only near the wall surface, we fabricated micro plasma actuators arrays using photolithography, and investigated the generated body force and jet characteristics. Velocity distribution measurements using a hot-wire anemometer were used to analyze the jet characteristics, and the body force distribution of the conventional and micro plasma actuators was clarified.