ELIMINATION OF THE CROSS-FLOW INSTABILITY ON THE SWEPT WING BOUNDARY LAYER BY MEANS OF DIELECTRIC BARRIER DISCHARGE

2015 ◽  
Vol 46 (8) ◽  
pp. 715-732
Author(s):  
Maxim Vladimirovich Ustinov
Keyword(s):  
Boundary Layer ◽  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Flow Instability ◽  
Cross Flow ◽  
Swept Wing ◽  
Dielectric Barrier ◽  
The Cross

scholarly journals Transition control in a three-dimensional boundary layer at elevated free stream turbulence using dielectric barrier discharge

2019 ◽  
Vol 486 (6) ◽  
pp. 668-672
Author(s):  
S. A. Baranov ◽  
A. Ph. Kiselev ◽  
I. A. Moralev ◽  
D. S. Sboev ◽  
S. N. Tolkachev ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Dielectric Barrier Discharge ◽  
Free Stream ◽  
Barrier Discharge ◽  
Flow Instability ◽  
Three Dimensional ◽  
Cross Flow ◽  
Dielectric Barrier ◽  
Free Stream Turbulence ◽  
Dimensional Boundary

The results of an experimental study of the effect of dielectric barrier discharge (DBR) actuator on laminar-turbulent transition in a three-dimensional boundary layer under influence of elevated free-stream turbulence are presented. The travelling cross-flow instability modes are dominated in transition in a base configuration. Their characteristics do not depend on a spanwise position. The DBD-actuator that generated stationary cross-flow vortices with the predefined spanwise wavelength when turned on was capable to reduce a turbulent spots production rate in comparison to the base regime.

scholarly journals Conditioning of cross-flow instability modes using dielectric barrier discharge plasma actuators

2017 ◽  
Vol 833 ◽  
pp. 164-205 ◽  
Author(s):  
Jacopo Serpieri ◽  
Srikar Yadala Venkata ◽  
Marios Kotsonis
Keyword(s):  
Boundary Layer ◽  
Discharge Plasma ◽  
Barrier Discharge ◽  
Flow Instability ◽  
Cross Flow ◽  
Plasma Actuators ◽  
Dielectric Barrier Discharge Plasma ◽  
Dielectric Barrier ◽  
Instability Modes ◽  
Barrier Discharge Plasma

In the current study, selective forcing of cross-flow instability modes evolving on a $45^{\circ }$ swept wing at $Re=2.17\times 10^{6}$ is achieved by means of spanwise-modulated plasma actuators, positioned near the leading edge. In the perspective of laminar flow control, the followed methodology holds on the discrete roughness elements/upstream flow deformation (DRE/UFD) approach, thoroughly investigated by e.g. Saric et al. (AIAA Paper 1998-781, 1998), Malik et al. (J. Fluid Mech., vol. 399, 1999, pp. 85–115) and Wassermann & Kloker (J. Fluid Mech., vol. 456, 2002, pp. 49–84). The possibility of using active devices for UFD provides several advantages over passive means, allowing for a wider range of operating $Re$ numbers and pressure distributions. In the present work, customised alternating current dielectric barrier discharge plasma actuators have been designed, manufactured and characterised. The authority of the actuators in forcing monochromatic stationary cross-flow modes at different spanwise wavelengths is assessed by means of infrared thermography. Moreover, quantitative spatio-temporal measurements of the boundary layer velocity field are performed using time-resolved particle image velocimetry. The results reveal distinct steady and unsteady forcing contributions of the plasma actuator on the boundary layer. It is shown that the actuators introduce unsteady fluctuations in the boundary layer, amplifying at frequencies significantly lower than the actuation frequency. In line with the DRE/UFD strategy, forcing a sub-critical stationary mode, with a shorter wavelength compared to the naturally selected mode, results in less amplified primary vortices and related fluctuations, compared to the critical forcing case. The effect of the forcing on the flow stability is further inspected by combining the measured actuators body force with the numerical solution of the laminar boundary layer and linear stability theory. The simplified methodology yields fast and computationally cheap estimates on the effect of steady forcing (magnitude and direction) on the boundary layer stability.

Reduction of friction drag by means of boundary layer laminarization using a dielectric barrier discharge

2012 ◽  
Vol 47 (4) ◽  
pp. 483-493
Author(s):  
M. N. Kogan ◽  
V. M. Litvinov ◽  
A. A. Uspenskii ◽  
M. V. Ustinov
Keyword(s):  
Boundary Layer ◽  
Dielectric Barrier Discharge ◽  
Barrier Discharge ◽  
Friction Drag ◽  
Dielectric Barrier

Receptivity and sensitivity of the leading-edge boundary layer of a swept wing

2015 ◽  
Vol 775 ◽  
Author(s):  
Gianluca Meneghello ◽  
Peter J. Schmid ◽  
Patrick Huerre
Keyword(s):  
Boundary Layer ◽  
Flow Instability ◽  
Cross Flow ◽  
Leading Edge ◽  
Open Loop ◽  
Base Flow ◽  
Local Instability ◽  
Swept Wing ◽  
Global Mode ◽  
Attachment Line

A global stability analysis of the boundary layer in the leading edge of a swept wing is performed in the incompressible flow regime. It is demonstrated that the global eigenfunctions display the features characterizing the local instability of the attachment line, as in swept Hiemenz flow, and those of local cross-flow instabilities further downstream along the wing. A continuous connection along the chordwise direction is established between the two local eigenfunctions. An adjoint-based receptivity analysis reveals that the global eigenfunction is most responsive to forcing applied in the immediate vicinity of the attachment line. Furthermore, a sensitivity analysis identifies the wavemaker at a location that is also very close to the attachment line where the corresponding local instability analysis holds: the local cross-flow instability further along the wing is merely fed by its attachment-line counterpart. As a consequence, global mode calculations for the entire leading-edge region only need to include attachment-line structures. The result additionally implies that effective open-loop control strategies should focus on base-flow modifications in the region where the local attachment-line instability prevails.

Free-stream turbulence and the development of cross-flow disturbances

2013 ◽  
Vol 735 ◽  
pp. 347-380 ◽  
Author(s):  
Robert S. Downs ◽  
Edward B. White
Keyword(s):  
Surface Roughness ◽  
Flow Problem ◽  
Free Stream ◽  
Flow Instability ◽  
Cross Flow ◽  
Stream Velocity ◽  
Swept Wing ◽  
Free Stream Turbulence ◽  
Flow Disturbances ◽  
The Cross

AbstractThe cross-flow instability that arises in swept-wing boundary layers has resisted attempts to describe the path from disturbance initiation to transition. Following concerted research efforts, surface roughness and free-stream turbulence have been identified as the leading providers of initial disturbances for cross-flow instability growth. Although a significant body of work examines the role of free-stream turbulence in the cross-flow problem, the data more relevant to the flight environment (turbulence intensities less than 0.07 %) are sparse. A series of recent experiments indicates that variations within this range may affect the initiation or growth of cross-flow instability amplitudes, hindering comparison among results obtained in different disturbance environments. To address this problem, a series of wind tunnel experiments is performed in which the free-stream turbulence intensity is varied between 0.02 % and 0.2 % of free-stream velocity,${U}_{\infty } $. Measurements of the stationary and travelling mode amplitudes are made in the boundary layer of a 1.83 m chord,$45{{}^\circ} $swept-wing model. These results are compared to those of similar experiments at higher turbulence levels to broaden the current knowledge of this portion of the cross-flow problem. It is observed that both free-stream turbulence and surface roughness contribute to the initiation of unsteady disturbances, and that free-stream turbulence affects the development of both stationary and unsteady cross-flow disturbances. For the range tested, enhanced free-stream turbulence advances the transition location except when a subcritically spaced roughness array is employed.

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