Study of Tip-Vortex Formation Using Large-Eddy Simulation

Ghias, Reza; Mittal, Rajat; Dong, Haibo; Lund, Thomas S.

doi:10.2514/6.2005-1280

Cited by 22 publications

(14 citation statements)

References 33 publications

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“…Remnants of the counter rotating vortex are the curvature of the streamlines in this area along with the existence of corresponding negative vorticity. This counter rotating vorticity can be also associated with the evolution of a secondary vortex during the formation of a single tip vortex on the wing observed by several investigators (Devenport et al [15], Ghias et al [21], Lombardi and Skinner [42]) and considered as important for the development of the vortex. In this context it is quite interesting to compare the half field of the presently measured vorticity contours with the corresponding plots (i.e.…”

Section: Discussionmentioning

confidence: 92%

“…In this context it is quite interesting to compare the half field of the presently measured vorticity contours with the corresponding plots (i.e. at x/c = 1.3) of a single tip-vortex calculated with LES by Ghias et al [21] presenting a counter rotating vorticity peak close to the main vortex. The head on collision of the penetrating streams and the interaction of the vorticity dipole with the outer shear are the key differences between the two cases.…”

Section: Discussionmentioning

confidence: 99%

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Multisensor Hot Wire Vorticity Probe Measurements of the Formation Field of Two Corotating Vortices

Romeos

Lemonis

Papailiou

2009

Flow Turbulence Combust

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Experimental evidence is reported, regarding the formation of a pair of co-rotating tip vortices by a split wing configuration, consisting of two half wings at equal and opposite angles of attack. Simultaneous measurements of the threedimensional vector fields of velocity and vorticity were conducted on a cross plane at a downstream distance corresponding to 0.3 cord lengths (near wake), using an in-house constructed 12-sensor hot wire anemometry vorticity probe. The probe consists of three closely separated orthogonal 4-wire velocity sensor arrays, measuring simultaneously the three-dimensional velocity vector at three closely spaced locations on a cross plane of the flow filed. This configuration makes possible the estimation of spatial velocity derivatives by means of a forward difference scheme of first order accuracy. Velocity measurements obtained with an X-wire are also presented for comparison. In this near wake location, the flow field is dictated by the pressure distribution established by the flow around the wings, mobilizing large masses of air and leading to the roll up of fluid sheets. Fluid streams penetrating between the wings collide, creating on the cross plane flow a stagnation point and an "impermeable" line joining the two vortex centres. Along this line fluid is directed towards the two vortices, expanding their cores and increasing their separation distance. This feeding process generates a dipole of opposite sign streamwise mean vorticity within each vortex. The rotational flow within the vortices obligates an adverse streamwise pressure gradient leading to a significant streamwise velocity deficit characterizing the vortices. The turbulent flow field is the result of temporal changes in the intensity of the vortex formation and changes in the position of the cores (wandering).

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Multisensor Hot Wire Vorticity Probe Measurements of the Formation Field of Two Corotating Vortices

Romeos

Lemonis

Papailiou

2009

Flow Turbulence Combust

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“…From this distribution, it was possible to estimate on the diameter of the vortex, which was defined as equalling the distance between the minimum and maximum peaks in the vertical velocity profile. 9,29 Finally, the circulation was calculated using:…”

Section: Particle Image Velocimetry Measurementsmentioning

confidence: 99%

Active Control of a Wing Tip Vortex with a Dielectric Barrier Discharge Plasma Actuator

Chappell

Angland

2012

6th AIAA Flow Control Conference

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An experimental investigation has been conducted into the active control of a wing tip vortex with a dielectric barrier discharge plasma actuator. The actuator was placed around the wing tip with the momentum added in the opposite direction to that of the cross stream flow. Particle image velocimetry measurements were performed on a low aspect ratio rounded tip NACA 0015 wing in a low speed wind tunnel at a maximum Reynolds number of 2.8 ×10 5 , based on the wing chord. Experiments were performed at various angles of attack. The current strength of the plasma actuator limited the maximum freestream velocity to 15 ms −1 . For low angles of attack (2 • and 6 • ), the near field results showed an increase in vortex size and a reduction in the core circulation when control was applied. The effectiveness of the actuator reduced with freestream velocity and angle of attack. The use of the plasma actuator was found to increase the velocity fluctuations close to the surface of the wing. At an angle of attack of 14 • , the actuator resulted in a smaller vortex and an increase in the core circulation. It was hypothesised that at this high angle of attack, the vorticity generated at the suction side electrodes was fed into the core, increasing the strength of the tip vortex. The results show that the potential of the plasma actuator for the near field control of the tip vortex is promising provided the angle of attack is low. NomenclatureA * Non-dimensionalised bounded within area of integration AR Aspect ratio b w Wing span, m C L Wing lift coefficient c Wing chord, m Re c Reynolds number based on main element chord r Radial distance measured from vortex centre, mm r 1 Radius of vortex, mm r max Maximum radial distance measured from vortex centre, mm S Surface area, m 2 s Wing semi-span, m t w Wing thickness, m U ∞ Freestream velocity, ms −1 v rms Root mean square velocity component in y direction, ms −1 v * θ Non-dimensionalised tangential velocity x, y, z Coorindates measured from model leading edge tip, m y c , z c Vortex centroid, m * PhD Student, Faculty of Engineering and the Environment. Student Member AIAA † Research Fellow, Faculty of Engineering and the Environment, Member AIAA.

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“…According to the wing tip vortex topology 12,13 and to results 14 showing that particular steady blowing configurations near the wing tip are effective, this present study aims at experimentally investigating DBD actuator devices for modifying the wing tip vortex of a rectangular wing placed with a straight tip at an incidence of 6° in a freestream flow of 10 m/s. Main objectives are to demonstrate actuator potentialities to modify the development, position and strength of these vortices, as well as to alter streamwise vorticity downstream of the wing trailing edge, by acting on the transversal component of the flow velocity.…”

Section: Introductionmentioning

confidence: 99%

Experimental studies of DBD actuator effects on wing tip vortex topology

Leroy

Molton²,

Carpels³

et al. 2012

6th AIAA Flow Control Conference

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Experiments studying the wing tip vortex, generated by a rectangular wing with a symmetric airfoil section and a straight tip, manipulated by surface plasma actuators are presented in this paper. Objectives are focused on modifying vortex development to alter streamwise vorticity downstream of the wing trailing edge. Actual limitation of the ionic wind magnitude obtained with DBD actuators leads to investigate vortex control by action on the transverse component of the freestream flow velocity. Different DBD arrangements installed near the wing tip were tested to examine effects of momentum addition, firstly on the pressure and suction side surfaces, and secondly, simultaneously located more precisely on the main vortex separation and attachment lines. Stereoscopic PIV measurements were performed in different planes orthogonal to the vortex development axis to visualize and characterize wing tip vortices. According to DBD arrangements, results of the actuation show a slight displacement of the wing tip vortex and a reduction of the mean streamwise vorticity level in its core. Nomenclature c = chord U 0 = freestream velocity X = chord axis Y = transverse axis Z = vertical axis U = chord axis velocity V = transverse axis velocity W = vertical axis velocity k = turbulent kinetic energy  x = streamwise vorticity

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Study of Tip-Vortex Formation Using Large-Eddy Simulation

Cited by 22 publications

References 33 publications

Multisensor Hot Wire Vorticity Probe Measurements of the Formation Field of Two Corotating Vortices

Multisensor Hot Wire Vorticity Probe Measurements of the Formation Field of Two Corotating Vortices

Active Control of a Wing Tip Vortex with a Dielectric Barrier Discharge Plasma Actuator

Experimental studies of DBD actuator effects on wing tip vortex topology

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