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.

Dielectric Barrier Discharge (DBD) Plasma Actuators for Flow Control in Turbine Engines: Simulation of Flight Conditions in the Laboratory by Density Matching

2019 ◽  
Vol 36 (2) ◽  
pp. 157-173
Author(s):  
David E. Ashpis ◽  
Douglas R. Thurman
Keyword(s):  
Flow Control ◽  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Test Chamber ◽  
Plasma Actuators ◽  
Chamber Pressure ◽  
Turbine Engines ◽  
Dbd Plasma ◽  
Dielectric Barrier ◽  
Actuator Performance

Abstract We address requirements for laboratory testing of AC Dielectric Barrier Discharge (AC-DBD) plasma actuators for active flow control in aviation gas turbine engines. The actuator performance depends on the gas discharge properties, which, in turn, depend on the pressure and temperature. It is technically challenging to simultaneously set test-chamber pressure and temperature to the flight conditions. We propose that the AC-DBD actuator performance depends mainly on the gas density, when considering ambient conditions effects. This enables greatly simplified testing at room temperature with only chamber pressure needing to be set to match the density at flight conditions. For turbine engines, we first constructed generic models of four engine thrust-classes; 300-, 150-, 50-passenger, and military fighter, and then calculated the densities along the engine at sea-level takeoff and altitude cruise conditions. The range of chamber pressures that covers all potential applications was found to be from 3 to 1256 kPa (0.03 to 12.4 atm), depending on engine-class, flight altitude, and actuator placement in the engine. The engine models are non-proprietary and can be used as reference data for evaluation requirements of other actuator types and for other purposes. We also provided examples for air vehicles applications up to 19,812 m (65,000 ft).

Test Conditions for Performance Characterization of Dielectric Barrier Discharge (DBD) Plasma Actuators for Active Flow Control in Jet Engines

2011 ◽  
Author(s):  
David E. Ashpis ◽  
Douglas R. Thurman
Keyword(s):  
Flow Control ◽  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Active Flow Control ◽  
Plasma Actuators ◽  
Dbd Plasma ◽  
Dielectric Barrier ◽  
Jet Engine ◽  
Active Flow

Dielectric Barrier Discharge (DBD) plasma actuators for active flow control in the jet engine need to be tested in the laboratory to characterize their performance at flight operating conditions. DBD plasma actuators generate a wall-jet electronically by creating weakly ionized plasma, therefore their performance is affected by gas discharge properties, which in turn depend on the pressure and temperature at the actuator placement location. Characterization of actuators is initially performed in a laboratory chamber without external flow. It is usually impractical to simultaneously set engine pressures and temperatures in a chamber, and a simplified approach is desired. It is assumed that the plasma discharge depends only on the gas density. Other temperature effects are assumed to be negligible. Therefore, tests can be performed at room temperature with chamber pressure set to yield the same density as in engine operating flight conditions. Engine data was obtained from four generic engine models; 300-, 150-, and 50-Passenger (PAX) aircraft engines, and a military jet-fighter engine. The static and total pressure, temperature, and density distributions along the engine were calculated for sea-level takeoff and altitude cruise, and the chamber pressures needed to test the actuators were calculated. The results show that testing has to be performed over a wide range of pressures from 12.4 to 0.03 atm, depending on the application. For example, if a DBD plasma actuator is to be placed at the compressor exit of a 300 PAX engine, it has to be tested at 12.4 atm for takeoff, and 6 atm for cruise conditions. If it is to be placed at the low-pressure turbine, it has to be tested at 0.5 and 0.2 atm, respectively. These results have implications for the feasibility and design of DBD plasma actuators for jet engine flow control applications. In addition, the distributions of unit Reynolds number, Mach number, and velocity along the engine are provided. The engine models are non-proprietary and this information can be used for evaluation of other types of actuators and for other purposes.

scholarly journals Investigation of a Dielectric Barrier Discharge Plasma Actuator to Control Turbulent Boundary Layer Separation

2020 ◽  
Vol 10 (6) ◽  
pp. 1911 ◽  
Author(s):  
Mahdi Hasan ◽  
Michael Atkinson
Keyword(s):  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Separated Flow ◽  
Boundary Layer Separation ◽  
Plasma Actuator ◽  
Dbd Plasma ◽  
Dielectric Barrier ◽  
Baseline Case

A numerical investigation was carried out to explore the effects of a dielectric barrier discharge (DBD) plasma actuator on a three-dimensional incompressible, separated flow. The test article selected for the simulations was the National Aeronautical and Space Administration (NASA) wall-mounted hump model. The simulations were run at a Reynolds number of 936,000, based on hump chord length, and a freestream Mach number of 0.1. Hybrid partially averaged Navier–Stokes/large-eddy simulations (PANS/LES) were completed using CALC-LES, a well-validated computational fluid dynamics (CFD) code, developed by Chalmers University of Technology. The baseline code was modified to simulate the effects of the actuator, which were modeled as source terms in the momentum equation and were assumed to be steady and constant in the span-wise direction. The numerical simulations were carried out for a baseline (no control) case and five plasma control cases. To optimize the performance of the actuator, the variation of actuator location and voltage frequency was investigated. For the baseline case, a comparison of time-averaged skin friction, the coefficient of pressure, and velocity profiles was made of the available experimental results. The results of the baseline case showed good agreement for a hybrid turbulence model, thus strengthening the solver’s ability to predict a three-dimensional separated flow with reasonable accuracy. The results with the plasma actuator turned on showed improved flow characteristics compared to the baseline simulations by reducing the region of separated flow. The actuator placed just downstream of the separation point at an operational frequency of 5kHz completely eliminated the separated flow for our test conditions.

Single-dielectric barrier discharge plasma actuator modelling and validation

2011 ◽  
Vol 669 ◽  
pp. 557-583 ◽  
Author(s):  
BENJAMIN E. MERTZ ◽  
THOMAS C. CORKE
Keyword(s):  
Flow Control ◽  
Dielectric Barrier Discharge ◽  
Body Force ◽  
Barrier Discharge ◽  
Plasma Actuator ◽  
Time Dependent ◽  
Plasma Actuators ◽  
Force Vector ◽  
Dielectric Barrier ◽  
Flow Simulations

Single-dielectric barrier discharge (SDBD) plasma actuators have gained a great deal of world-wide interest for flow-control applications. With this has come the need for flow-interaction models of plasma actuators that can be used in computational flow simulations. SDBD plasma actuators consist of two electrodes: one uncovered and exposed to the air and the other encapsulated by a dielectric material. An AC electric potential is supplied to the electrodes. When the AC potential is large enough, the air in the region over the encapsulated electrode ionizes. The ionized air in the presence of the electric field results in a space–time dependent body force vector field. The body force is the mechanism for flow control. This study describes a semi-empirical model that has been developed to capture the dynamic nature of the local air ionization and time-dependent body force vector distribution. Validation of the model includes comparisons to experimentally measured space–time charge distribution and the time-resolved and time-averaged body force. Two flow simulations are then used to further validate the SDBD plasma actuator model. These involved an impulsively started plasma actuator in still air, and the flow around a circular cylinder in which plasma actuators were used to suppress the Karman vortex street. In both cases, the simulations agreed well with the experiments.

scholarly journals Effects of Input Voltage and Freestream Velocity on Active Flow Control of Passage Vortex in a Linear Turbine Cascade Using Dielectric Barrier Discharge Plasma Actuator

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 764 ◽  
Author(s):  
Takayuki Matsunuma ◽  
Takehiko Segawa
Keyword(s):  
Flow Control ◽  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Active Flow Control ◽  
Plasma Actuator ◽  
Turbine Cascade ◽  
Freestream Velocity ◽  
Dielectric Barrier ◽  
Passage Vortex ◽  
Active Flow

Passage vortex exists as one of the typical secondary flows in turbomachines and generates a significant total pressure loss and degrades the aerodynamic performance. Herein, a dielectric barrier discharge (DBD) plasma actuator was utilized for an active flow control of the passage vortex in a linear turbine cascade. The plasma actuator was installed on the endwall, 10 mm upstream from the leading edge of the turbine cascade. The freestream velocity at the outlet of the linear turbine cascade was set to range from UFS,out = 2.4 m/s to 25.2 m/s, which corresponded to the Reynolds number ranging from Reout = 1.0 × 104 to 9.9 × 104. The two-dimensional velocity field at the outlet of the linear turbine cascade was experimentally analyzed by particle image velocimetry (PIV). At lower freestream velocity conditions, the passage vortex was almost negligible as a result of the plasma actuator operation (UPA,max/UFS,out = 1.17). Although the effect of the jet induced by the plasma actuator weakened as the freestream velocity increased, the magnitude of the peak vorticity was reduced under all freestream velocity conditions. Even at the highest freestream velocity condition of UFS,out = 25.2 m/s, the peak value of the vorticity was reduced approximately 17% by the plasma actuator operation at VAC = 15 kVp-p (UPA,max/UFS,out = 0.18).

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