Fluidic Control of a Turret Wake, Part I: Aerodynamic Effects

Vukašinović, Bojan; Glezer, Ari; Gordeyev, Stanislav; Jumper, Eric J.; Kibens, Valdis

doi:10.2514/6.2009-816

Cited by 14 publications

(30 citation statements)

References 20 publications

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“…The array of synthetic jets introduces small-scale, highly dissipative structures into the attached boundary layer upstream of the window aperture. This flow actuation was shown to lead to flow-separation delay on the window's surface; up to a 10-degree delay in separation was observed to an elevation angle of 139 degrees 4 . A broad-band suppression of the turbulent …”

Section: Imentioning

confidence: 99%

“…The actuators' principle of operation is described in [4,8]; they were zero-mass, blowing-suction type piezo actuators, often referred to as synthetic jets 10 . In preliminary studies 4,5 these actuators (although at a slightly different arrangements) were shown to delay the separation point and dissipate small-scale structures behind the turret with a corresponding reduction in the level of optical distortions by as much as 40% at M = 0.3.…”

Section: Active Flow Controlmentioning

confidence: 99%

“…To measure optical aberrations at higher elevation angles and investigate strategies to mitigate these large levels of optical distortions at high back-looking angles, as well to address Reynolds number effects and scaling issues, a two-foot conformal window turret was tested for a range of back-looking angles from 129 to 149 degrees and Mach numbers between 0.3 and 0.5 4,5 . The turret was instrumented with static ports to measure the location of the flow separation line.…”

Section: Imentioning

confidence: 99%

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Hybrid Flow Control of a Turret Wake, Part II: Aero-Optical Effects

Gordeyev

Jumper

Vukašinović

et al. 2010

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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This paper presents the optical results of using combined passive and active flow control to improve the aero-optical environments around a conformal-window, hemisphere-oncylinder turret. Several wavefront sensors were used to directly measure optical distortions at several back-looking angles. It was shown that the hybrid flow control significantly reduces levels of optical distortions for elevation angles as high as 148 degrees at M = 0.3. The paper also devotes considerable attention to overcoming environmental conditions present in large-scale wind tunnels. I. BackgroundN the last decade or so the research in using turrets to transmit laser beams from subsonic airborne platforms has greatly intensified. While a turret provides a convenient mechanical system to point-and-track the laser beam, the wake flow behind this bluff-body turret is both turbulent and complex with many vortical structures present. These structures are known to create significant density gradients and related aero-optical distortions 1 when the laser beam is transmitted through the wake of the turret even at low transonic speeds (see [2] and references therein, for instance). Left untreated, these detrimental aero-optical effects greatly reduce the laser-beam intensity in the farfield.An earlier investigation of the optical environment around a one-foot conformal-window turret for the range of the elevation angles between 60 and 132 degrees 3 in the zenith plane showed the level of optical distortions increases for backward looking angles above 120 degrees. To measure optical aberrations at higher elevation angles and investigate strategies to mitigate these large levels of optical distortions at high back-looking angles, as well to address Reynolds number effects and scaling issues, a two-foot conformal window turret was tested for a range of back-looking angles from 129 to 149 degrees and Mach numbers between 0.3 and 0.5 4,5 . The turret was instrumented with static ports to measure the location of the flow separation line. Velocity profiles in the wake downstream of the turret were measured using a single hot-wire and the surface flow topology was studied with oil flow visualization. Optical measurements were performed using a Malley Probe. In order to study the mitigating effects of active flow control the turret was equipped with an array of synthetic jets upstream of the window aperture. In previous studies these actuators were shown to be effective in suppressing turbulence behind a bluffbody turret at Re D = 8·105 [6], as well as behind a 10-inch hemispherical turret 7 , where significant suppression of turbulent fluctuations and reduction in optical distortions were observed up to M = 0.45. The array of synthetic jets introduces small-scale, highly dissipative structures into the attached boundary layer upstream of the window aperture. This flow actuation was shown to lead to flow-separation delay on the window's surface; up to a 10-degree delay in separation was observed to an elevation angle of 139 degrees 4 . A broad-band sup...

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Section: Imentioning

confidence: 99%

Section: Active Flow Controlmentioning

confidence: 99%

Section: Imentioning

confidence: 99%

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Hybrid Flow Control of a Turret Wake, Part II: Aero-Optical Effects

Gordeyev

Jumper

Vukašinović

et al. 2010

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

Self Cite

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“…Note that based on (27) and (28), the bounding constant ρ Λ1 depends only on elements i + 1 to n of the control gain matrix k s due to the strictly upper triangular nature of T. Thus, the element μ 01 t of the control vector μ 0 t does not appear in the term Λ ρ . This fact will be utilized in the subsequent stability proof [9].…”

Section: Propertymentioning

confidence: 99%

“…Various approaches have recently been developed for aircraft tracking control using SJAs (e.g., see [8,[10][11][12][13]), where the SJA actuator uncertainty is compensated using adaptive control methods or neural networks. Other popular approaches for SJA-based control are computational fluid dynamics-(CFD-) based numerical techniques (see [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]). Adaptive control, neural networkbased control, and numerical CFD methods have been shown to be effective in their respective SJA-based control tasks.…”

Section: Introductionmentioning

confidence: 99%

Synthetic Jet Actuator-Based Aircraft Tracking Using a Continuous Robust Nonlinear Control Strategy

Ramos-Pedroza¹,

MacKunis²,

Reyhanoglu³

2017

International Journal of Aerospace Engineering

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A robust nonlinear control law that achieves trajectory tracking control for unmanned aerial vehicles (UAVs) equipped with synthetic jet actuators (SJAs) is presented in this paper. A key challenge in the control design is that the dynamic characteristics of SJAs are nonlinear and contain parametric uncertainty. The challenge resulting from the uncertain SJA actuator parameters is mitigated via innovative algebraic manipulation in the tracking error system derivation along with a robust nonlinear control law employing constant SJA parameter estimates. A key contribution of the paper is a rigorous analysis of the range of SJA actuator parameter uncertainty within which asymptotic UAV trajectory tracking can be achieved. A rigorous stability analysis is carried out to prove semiglobal asymptotic trajectory tracking. Detailed simulation results are included to illustrate the effectiveness of the proposed control law in the presence of wind gusts and varying levels of SJA actuator parameter uncertainty.

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