Effect of a Trailing-Edge Jet on Fin Buffeting

Phillips, Steve; Lambert, Caroline; Gursul, Ismet

doi:10.2514/2.3135

Cited by 17 publications

(5 citation statements)

References 23 publications

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“…The values of the momentum coefficient used in the experiments are realistic for thrust-vectoring applications and also have been used by previous investigators [8][9][10][11][12][13]. Experiments were conducted for both periodic and transient (ramp) variations of the jet momentum coefficient.…”

Section: A Experimental Setupmentioning

confidence: 99%

“…At a sufficiently high angle of attack, the vortices undergo a sudden expansion known as vortex breakdown [6,7], which has adverse aerodynamic effects on delta wing performance. Several investigations [8][9][10][11][12][13] demonstrated that thrust-vectoring jets at the trailing edge could delay vortex breakdown significantly, up to 50% of wing chord. Therefore, significant effects on the aerodynamic forces and moments on the wings are expected.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Unsteady Trailing-Edge Blowing on Delta Wing Aerodynamics

Jiang

Wang

Gursul

2010

Journal of Aircraft

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The effects of unsteady trailing-edge blowing on delta wing aerodynamics were investigated experimentally to understand the aerodynamics-propulsion interaction for dynamic thrust vectoring. Two models with sweep angles of 50 and 65 deg, representing nonslender and slender delta wings, respectively, were tested in a water tunnel. Flow visualization and velocity and force measurements were conducted at stall and poststall incidences. For the periodic blowing, it was found that the dynamic response of leading-edge vortex breakdown and wing normal force coefficient exhibit phase lags for both nonslender and slender delta wings. The estimated time constants are larger than those reported in the literature for unsteady wings undergoing pitching or plunging. In the case of transient blowing, the time delay for the decelerating jet is significantly larger than that for the accelerating jet. The variation of the circulation and the reattachment process near the wing surface were studied by means of velocity measurements. The range of the estimated time constants is similar at the stall and poststall incidences for both the slender and nonslender wings.= dimensionless frequency, fc=U 1 q = freestream dynamic pressure Re = Reynolds number S w = wing surface area s = local semispan T = period t = wing thickness or time U jet = jet velocity U 1 = freestream velocity u = velocity X bd = distance from wing apex to leading-edge vortex breakdown location y jet = spanwise location of jet = wing incidence = jet pitch angle = circulation X bd = peak-to-peak amplitude of the variation of the vortex breakdown location = leading-edge sweep angle = fluid kinematic viscosity = air density = time constant = phase lag ! = angular frequency ! x = streamwise vorticity

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Section: A Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Unsteady Trailing-Edge Blowing on Delta Wing Aerodynamics

Jiang

Wang

Gursul

2010

Journal of Aircraft

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“…Vortex breakdown types are categorized into seven different kinds [26], three of which are more common over delta wings, spiral, double helix, and bubble type. Sarpkaya [27], [28] [11], [35] and unsteady blowing [36].…”

Section: Vortex Breakdownmentioning

confidence: 99%

Effect of thickness-to-chord ratio on aerodynamics of non-slender delta wing

Ghazijahani

Yavuz

2019

Aerospace Science and Technology

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, 84 pages Flow characterization over delta wings have gained attention in recent decades due to their prevailing usage in designs of unmanned air vehicles (UAVs). In literature, only a few studies have reported wing thickness effect on both the aerodynamic performance and detailed flow structure over delta wings. In the present investigation, the effect of thickness-to-chord (/) ratio on aerodynamics of a non-slender delta wing with 45 degree sweep angle is characterized in a low-speed wind tunnel using laser illuminated smoke visualization, surface pressure measurements, particle image velocimetry, and force measurements. The delta wings with / ratios varying from 2 % to 15 % are tested at broad ranges of angle of attack and Reynolds number. The results indicate that the effect of / ratio on flow structure is quite substantial. Considering the low angles of attack where the wings experience leading edge vortex structure, the strength of the vortex structure increases as the / ratio increases. However, low / ratio wings have pronounced surface separations at higher angle of attack compared to the high / ratio wings. These results are well supported by the force measurements such that high / ratio wings induce higher lift coefficients, CL, at vi low angles of attack, whereas maximum CL values are higher and appear at higher angle of attack for low / ratio wings. This indicates that low / ratio wings are more resistive to the stall condition. Considering the lift-to-drag ratio, CL/CD, increase in / ratio induces remarkable drop in CL/CD values.

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“…To prevent this undesirable outcome, there has been a great deal of research in this area. [1][2][3][4][5][6] A majority of the methods proposed feature either alteration of the flow field around the vertical fin, structural modification of the fin and/or active control. For example, active control of the fin using surface bonded PZT patches/fiber actuators [1][2][3] and an actively controlled rudder 4,5 have been studied.…”

Section: Introductionmentioning

confidence: 99%

“…Regarding the control of flow around the fin, several techniques have been applied to change either the position of the vortex with respect to the fin or delay vortex breakdown with blowing, suction on the wing surface, addition of fences, and variable position leading-edge extensions. 6 The work summarized in this paper is the second and final part of a two part project lead by Middle East Technical University (METU). The first part of the research project dealt with the design of the scaled fin and the determination of optimal actuator/sensor placement locations using Finite Element Methods (FEM).…”

Section: Introductionmentioning

confidence: 99%

Active Vibration Control of a Smart Fin

Ulker

Nalbantoglu

Chen³

et al. 2009

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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This paper summarizes the design and wind tunnel experimental verifications of robust H ∞ controllers for active vibration suppression of a dynamically scaled F-18 vertical smart fin. The smart fin consists of a cantilevered aluminium plate structure with surface bonded piezoelectric (Lead-Zirconate-Titanete, PZT) patches, Integrated Circuit Piezoelectric (ICP) type accelerometers and strain gauges. For H ∞ controller design, the transfer function of the fin was first estimated outside the wind tunnel. Then, experiments were carried out to determine the aeroelastic characteristics of the smart fin at free flow and vortical (i.e. buffet) flow conditions. Variable air speeds and Angle of Orientations (AoO) were considered in both flow conditions. Significant shifts in vibration frequencies and the damping ratios were observed at the various values of airspeed and AoO. Taking into account these variations, the H∞ controllers were designed to suppress the fin's buffeting response at the first and second bending and first torsional modes. A second set of wind tunnel experiments was conducted to verify the performance of the designed H∞ controllers at various flow scenarios. Successful vibration suppression levels were obtained within the desired frequency intervals.

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Effect of a Trailing-Edge Jet on Fin Buffeting

Cited by 17 publications

References 23 publications

Effects of Unsteady Trailing-Edge Blowing on Delta Wing Aerodynamics

Effects of Unsteady Trailing-Edge Blowing on Delta Wing Aerodynamics

Effect of thickness-to-chord ratio on aerodynamics of non-slender delta wing

Active Vibration Control of a Smart Fin

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