scholarly journals Dynamic Burst Actuation to Enhance the Flow Control Authority of Plasma Actuators

Aerospace ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 396
Author(s):  
Takuto Ogawa ◽  
Kengo Asada ◽  
Satoshi Sekimoto ◽  
Tomoaki Tatsukawa ◽  
Kozo Fujii

A computational study was conducted on flows over an NACA0015 airfoil with dielectric barrier discharge (DBD) plasma. The separated flows were controlled by a DBD plasma actuator installed at the 5% chord position from the leading edge, where operated AC voltage was modulated with the duty cycle not given a priori but dynamically changed based on the flow fluctuations over the airfoil surface. A single-point pressure sensor was installed at the 40% chord position of the airfoil surface and the DBD plasma actuator was activated and deactivated based on the strength of the measured pressure fluctuations. The Reynolds number was set to 63,000 and flows at angles of attack of 12 and 16 degrees were considered. The three-dimensional compressible Navier–Stokes equations including the DBD plasma actuator body force were solved using an implicit large-eddy simulation. Good flow control was observed, and the burst frequency proven to be effective in previous fixed burst frequency studies is automatically realized by this approach. The burst frequency is related to the characteristic pressure fluctuation; our approach was improved based on the findings. This improved approach realizes the effective burst frequency with a lower control cost and is robust to changing the angle of attack.

Author(s):  
Kengo Asada ◽  
Kozo Fujii

The relation between aerodynamic characteristics and the effectiveness of separation control with the DBD plasma actuator over the airfoil are discussed. The flow-fields around the NACA0015 airfoil are simulated with implicit large-eddy simulation using compact difference scheme. The normal mode generates moderately separated region over the airfoil and gains lift by negative pressure at the vortex center. The burst mode with nondimensional burst frequency of 1 enhances the vortex shedding from the separation shear layer and avoid the massive separation from the leading edge. However, the lift coefficient oscillate very much, in this case. The burst mode with nondimensional burst frequency of 6 improves the airfoil performance by suppressing the separation region. These facts indicate that the unsteady aerodynamic characteristics must be discussed when the effectiveness of separation control is evaluated.


2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Theodoros Michelis ◽  
Marios Kotsonis

A wind tunnel study is conducted toward hybrid flow control of a full scale transport truck side mirror at ReD=3.2×105. A slim guide vane is employed for redirecting high-momentum flow toward the mirror wake region. Leading edge separation from the guide vane is reduced or eliminated by means of an alternating current -dielectric barrier discharge (AC-DBD) plasma actuator. Particle image velocimetry (PIV) measurements are performed at a range of velocities from 15 to 25 m/s and from windward to leeward angles from -5deg to 5deg. Time-averaged velocity fields are obtained at the center of the mirror for three scenarios: (a) reference case lacking any control elements, (b) guide vane only, and (c) combination of the guide vane and the AC-DBD plasma actuator. The comparison of cases demonstrates that at 25 m/s windward conditions (-5deg) the guide vane is capable of recovering 17% momentum with respect to the reference case. No significant change is observed by activating the AC-DBD plasma actuator. In contrast, at leeward conditions (5deg), the guide vane results in a −20% momentum loss that is rectified to a 6% recovery with actuation. The above implies that for a truck with two mirrors, 23% of momentum may be recovered.


2019 ◽  
Author(s):  
Takumi Abe ◽  
Kengo Asada ◽  
Satoshi Sekimoto ◽  
Koji Fukudome ◽  
Hiroya Mamori ◽  
...  

2014 ◽  
Vol 80 (813) ◽  
pp. FE0118-FE0118 ◽  
Author(s):  
Yasuaki KOZATO ◽  
Yuta HIROSE ◽  
Satoshi KIKUCHI ◽  
Shigeki IMAO

Author(s):  
Satoshi Shimomura ◽  
Takuto Ogawa ◽  
Satoshi Sekimoto ◽  
Taku Nonomura ◽  
Akira Oyama ◽  
...  

This paper experimentally investigates the effectiveness of a closed-loop flow control method using a DBD plasma actuator for a NACA0015 airfoil, in which the surface pressure fluctuation is fed back to the system; the actuator was driven when the pressure fluctuation exceeds the setup threshold. The Reynolds number based on the chord length is set to 63,000 and the angle of attack is in the range from 12 to 15 degrees. The actuator was installed on the surface at 5% of the chord length from the leading edge. The results show that the closed-loop control worked better than the continuous operation. In the angle of attack of 12 and 14 degrees, the complete attached flow was attained by setting the appropriate threshold value of the pressure fluctuation. On the other hand, in 15 degrees, although the complete attached flow was not attained, the flow separation was partially suppressed.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Junjie Niu ◽  
Weimin Sang ◽  
Feng Zhou ◽  
Dong Li

Purpose This paper aims to investigate the anti-icing performance of the nanosecond dielectric barrier discharge (NSDBD) plasma actuator. Design/methodology/approach With the Lagrangian approach and the Messinger model, two different ice shapes known as rime and glaze icing are predicted. The air heating in the boundary layer over a flat plate has been simulated using a phenomenological model of the NSDBD plasma. The NSDBD plasma actuators are planted in the leading edge anti-icing area of NACA0012 airfoil. Combining the unsteady Reynolds-averaged Navier–Stokes equations and the phenomenological model, the flow field around the airfoil is simulated and the effects of the peak voltage, the pulse repetition frequency and the direction arrangement of the NSDBD on anti-icing performance are numerically investigated, respectively. Findings The agreement between the numerical results and the experimental data indicates that the present method is accurate. The results show that there is hot air covering the anti-icing area. The increase of the peak voltage and pulse frequency improves the anti-icing performance, and the direction arrangement of NSDBD also influences the anti-icing performance. Originality/value A numerical strategy is developed combining the icing algorithm with the phenomenological model. The effects of three parameters of NSDBD on anti-icing performance are discussed. The predicted results show that the anti-icing method is effective and may be helpful for the design of the anti-icing system of the unmanned aerial vehicle.


Author(s):  
Ehsan Asgari ◽  
Mehran Tadjfar

In this study, we have applied and compared two active flow control (AFC) mechanisms on a pitching NACA0012 airfoil at Reynolds number of 1 × 106 using 2-D computational fluid dynamics (CFD). These mechanisms are continuous blowing and suction which are applied separately on the airfoil which pitches around its quarter-chord in a sinusoidal motion. The location for suction and blowing was determined in our previous study based on the formation of a counter clock-wise vortex near the leading-edge. In our current study, we have compared the effectiveness of pure blowing and pure suction in suppressing the dynamic stall vortex (DSV) which is the main contributor to the drag increase, particularly near the maximum angle of attack (AOA) and in early downstroke motion. The blowing/suction slot is considered as a dent on the airfoil surface which enables the AFC to perform in a tangential manner. This configuration would allow blowing jet to penetrate further downstream and was shown to be more effective compared to a cross-flow orientation. We have compared the two aforementioned mechanisms in terms of hysteresis loops of lift and drag coefficients and have demonstrated the dynamics of flow in controlled and uncontrolled situations.


2017 ◽  
Vol 31 (32) ◽  
pp. 1850038 ◽  
Author(s):  
Xin Zhang ◽  
Huaxing Li ◽  
Kwing So Choi ◽  
Longfei Song

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.


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