Separation Control from the Flap of a High-Lift Airfoil Using DBD Plasma Actuation

Turbulent boundary layer separation is an important issue for a variety of applications, one of which is S-shaped aircraft engine intakes. The turbulent separation at the engine intake causes inlet flow distortion, which can deteriorate engine performance, cause fatigue and reduce engine component life. Various flow control techniques have been applied for turbulent boundary layer separation control, such as vortex generators, vortex generator jets and synthetic jets. The recent advent of dielectric barrier discharge (DBD) plasma actuators can potentially provide a robust method for the control of turbulent boundary layer separation. Compared to other flow control techniques, these new actuators are simple, robust and devoid of moving mechanical parts, which make them ideal for aerodynamic applications. The present work studies the effects of DBD plasma actuators on the suppression of 2-D turbulent boundary layer separation induced by an imposed adverse pressure gradient. First, the flow field with and without actuation in a low-speed wind tunnel is investigated experimentally by Particle Image Velocimetry (PIV) measurements. The results show that plasma actuation can suppress turbulent boundary layer separation in both continuous and pulsed modes. In the pulsed mode, the actuation with an optimal actuation frequency, corresponding to a dimensionless frequency of order one, is found to most effectively suppress the turbulent separation. Moreover, the effects of plasma actuation on the flow is demonstrated and analyzed by using Proper Orthogonal Decomposition (POD). The effect of the actuation is found to be correlated to the second POD mode which corresponds to large flow fluctuations.

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High Lift Airfoil Leading Edge Separation Control with Nanosecond Pulse DBD Plasma Actuators

5th Flow Control Conference ◽

10.2514/6.2010-4256 ◽

2010 ◽

Cited By ~ 21

Author(s):

Jesse Little ◽

Keisuke Takashima ◽

Munetake Nishihara ◽

Igor Adamovich ◽

Mo Samimy

Keyword(s):

Leading Edge ◽

Nanosecond Pulse ◽

Plasma Actuators ◽

Separation Control ◽

Dbd Plasma ◽

High Lift ◽

Edge Separation

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Application of an Integrated Flow and DBD Plasma Actuation Model to a High-Lift Airfoil: Part I — RANS

Volume 1: Symposia ◽

10.1115/ajkfluids2015-14213 ◽

2015 ◽

Author(s):

Hua Shan ◽

Shawn Aram ◽

Yu-Tai Lee

Keyword(s):

Numerical Simulation ◽

Charge Density ◽

Flow Separation ◽

Body Force ◽

Force Model ◽

Simulation Tool ◽

Dbd Plasma ◽

High Lift ◽

Net Charge ◽

Plasma Actuation

An integrated numerical simulation tool that couples the Reynolds averaged Navier-Stokes (RANS) or the large eddy simulation (LES) solver for incompressible flows with the dielectric barrier discharge (DBD) electro-hydrodynamic (EHD) body force model has been developed. The EHD body force model is based on solving the electrostatic equations for the electric potential due to applied voltage and the net charge density due to ionized air. The boundary condition for the charge density on the dielectric surface is obtained from a Space-Time Lumped-Element (STLE) circuit model that accounts for the time and space dependence of air ionization on the input voltage amplitude, frequency, electrode geometry, and dielectric properties. The development of the numerical simulation tool is based on the framework of NavyFOAM using a multi-domain approach. The electric potential equation, the net charge density equation, and the flow equations are solved in separate computational domains. All equations are discretized in space using the cell-centered finite volume method. Parallel computation is implemented using domain-decomposition and message passing interface (MPI). Due to a large disparity in time scales between the electric discharge and the flow, a multiple sub-cycle technique is used in coupling the plasma solver and the flow solver. This paper focuses on its application to numerical simulation of flow separation and control over a high-lift flapped airfoil at a Reynolds number of 240,000. The 2-D unsteady RANS simulation utilized the Wilcox k-ω, the SST k-ω, and the k-kl-ω turbulence models. For the baseline case, in comparison with the measurement, the k-kl-ω model captures the feature of the unsteadiness of flow field associated with flow separation and shedding of vortices, better than the Wilcox k-ω and SST k-ω models. In the RANS simulations for flow separation control with DBD plasma actuation, the actuator is driven by voltage signals of a continuous or an amplitude-modulated sine waveform with a range of voltage amplitudes. The numerical results indicate that the modulated forcing is more effective than the continuous forcing for a certain range of applied voltages. The electrical power consumption calculated by the plasma model fits to a parabolic curve as a function of the root-mean-square of applied voltage.

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Experimental Comparison of DBD Plasma Actuators for Low Reynolds Number Separation Control

Journal of Turbomachinery ◽

10.1115/1.4006517 ◽

2012 ◽

Vol 135 (1) ◽

Cited By ~ 6

Author(s):

Christopher R. Marks ◽

Rolf Sondergaard ◽

Mitch Wolff ◽

Rich Anthony

Keyword(s):

Reynolds Number ◽

Low Reynolds Number ◽

Turbine Blades ◽

Plasma Actuators ◽

Experimental Comparison ◽

Separation Control ◽

Suction Surface ◽

Dbd Plasma ◽

Low Reynolds ◽

Low Reynolds Number Airfoil

This paper presents experimental work comparing several Dielectric Barrier Discharge (DBD) plasma actuator configurations for low Reynolds number separation control. Actuators studied here are being investigated for use in a closed loop separation control system. The plasma actuators were fabricated in the U.S. Air Force Research Laboratory Propulsion Directorate’s thin film laboratory and applied to a low Reynolds number airfoil that exhibits similar suction surface behavior to those observed on Low Pressure (LP) Turbine blades. In addition to typical asymmetric arrangements producing downstream jets, one electrode configurations was designed to produce an array of off axis jets, and one produced a spanwise array of linear vertical jets in order to generate vorticity and improved boundary layer to freestream mixing. The actuators were installed on an airfoil and their performance compared by flow visualization, surface stress sensitive film (S3F), and drag measurements. The experimental data provides a clear picture of the potential utility of each design. Experiments were carried out at four Reynolds numbers, 1.4 × 105, 1.0 × 105, 6.0 × 104, and 5.0 × 104 at a-1.5 deg angle of attack. Data was taken at the AFRL Propulsion Directorate’s Low Speed Wind Tunnel (LSWT) facility.

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Plasma actuation effect on a NACA 4412 airfoil

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-04-2021-0101 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Burak Karadag ◽

Cem Kolbakir ◽

Ahmet Selim Durna

Keyword(s):

Reynolds Number ◽

Flow Separation ◽

Open Loop ◽

Electrode Configuration ◽

Small Scale ◽

Low Velocity ◽

Dbd Plasma ◽

Content Type ◽

Plasma Actuation ◽

Electric Wind

Purpose This paper aims to investigate the effects of a dielectric barrier discharge (DBD) plasma actuator (PA) qualitatively on aerodynamic characteristics of a 3 D-printed NACA 4412 airfoil model. Design/methodology/approach Airflow visualization study was performed at a Reynolds number of 35,000 in a small-scale open-loop wind tunnel. The effect of plasma actuation on flow separation was compared for the DBD PA with four different electrode configurations at 10°, 20° and 30° angles of attack. Findings Plasma activation may delay the onset of flow separation up to 6° and decreases the boundary layer thickness. The effects of plasma diminish as the angle of attack increases. Streamwise electrode configuration, in which electric wind is produced in a direction perpendicular to the freestream, is more effective in the reattachment of the airflow compared to the spanwise electrode configuration, in which the electric wind and the free stream are in the same direction. Practical implications The Reynolds number is much smaller than that in cruise aircraft conditions; however, the results are promising for low-velocity subsonic airflows such as improving control capabilities of unmanned aerial vehicles. Originality/value Superior efficacy of spanwise-generated electric wind over streamwise-generated one is demonstrated at a very low Reynolds number. The results in the plasma aerodynamics literature can be reproduced using ultra-low-cost off-the-shelf components. This is important because high voltage power amplifiers that are frequently encountered in the literature may be prohibitively expensive especially for resource-limited university aerodynamics laboratories.

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