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High-Lift Airfoil Separation Control with Dielectric Barrier Discharge Plasma Actuators

Little, Jesse
http://rave.ohiolink.edu/etdc/view?acc_num=osu1267836038

Abstract Details

2010, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
This work examines the performance of dielectric barrier discharge (DBD) plasma actuators for controlling separation from the leading edge and trailing edge flap shoulder of a supercritical high-lift airfoil. DBD plasma actuators driven by both typical AC voltages (AC-DBD) and more developmental nanosecond duration pulses (NS-DBD) are investigated. Characterization of the two actuators shows that very different behavior is created when exciting the plasma discharge using these two waveforms. The AC-DBD plasma actuator functions through electrohydrodynamic effects that introduce zero net mass, but nonzero net momentum into the flow. Conversely, the electrohydrodynamic effects of the NS-DBD are quite weak suggesting thermal effects from rapid localized heating by the plasma are responsible for control authority. The performance of both devices as separation control actuators is tested on a high-lift airfoil system. The AC-DBD is effective for controlling turbulent boundary layer separation from a deflected trailing edge flap between Reynolds numbers of 240,000 and 750,000. Momentum coefficients for the AC-DBD plasma actuator are generally an order of magnitude lower than those usually employed for such studies yet control authority is still realized through amplification of natural vortex shedding from the flap shoulder. The corresponding lift enhancement is primarily due to upstream effects from increased circulation around the entire model rather than full separated flow reattachment to the deflected flap surface. Lift enhancement via instability amplification is found to be relatively insensitive to changes in angle of attack provided that the separation location and underlying dynamics do not change. Control authority decreases with increasing Reynolds number and flap deflection highlighting the necessity for further optimization of AC-DBD plasma actuators for use in realistic takeoff and landing transport aircraft applications. As a whole, these findings compare favorably to studies on a similar high-lift platform using piezoelectric driven zero net mass flux actuation. The NS-DBD plasma actuator is ineffective for controlling separation from the deflected trailing edge flap. However, the device is found to be superior to the tested AC-DBD plasma actuators for controlling leading edge separation and rivals the performance of a passive droop by extending the stall angle by six degrees in the Reynolds number range 750,000-1,000,000. Detailed flow diagnostics show the NS-DBD plasma actuator functions as an active trip for pre-stall incidence angles and generates coherent spanwise vortices that entrain freestream momentum into the separated region at post-stall angles. These structures are generated across all surveyed frequencies, but optimal dimensionless frequencies for controlling separation are in the range four to six depending on the incidence angle. The contrasting performance of the NS-DBD plasma actuator at the leading and trailing edge in comparison to the AC-DBD is discussed and recommendations for future work are provided.
Mo Samimy, PhD (Advisor)
Igor Adamovich, PhD (Committee Member)
Michael Dunn, PhD (Committee Member)
James Gregory, PhD (Committee Member)
Andrea Serrani, PhD (Committee Member)
241 p.
Fluid Dynamics; Mechanical Engineering
airfoils; plasma; flow control

Recommended Citations

Citations

  • Little, J. (2010). High-Lift Airfoil Separation Control with Dielectric Barrier Discharge Plasma Actuators [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1267836038

    APA Style (7th edition)

  • Little, Jesse. High-Lift Airfoil Separation Control with Dielectric Barrier Discharge Plasma Actuators. 2010. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1267836038.

    MLA Style (8th edition)

  • Little, Jesse. "High-Lift Airfoil Separation Control with Dielectric Barrier Discharge Plasma Actuators." Doctoral dissertation, Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1267836038

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.