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

Romeos, Alexandros; Lemonis, G.; Papailiou, D. D.

doi:10.1007/s10494-008-9193-8

Cited by 6 publications

(5 citation statements)

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“…The corresponding plots of the stream-wise vorticity component, Ω x , estimated by the spatial differentiation of the cross-plane velocity field are presented in Figure 6. On the first measuring station, the vorticity associated with each vortex is characterized by two adjacent peaks of positive and negative vorticity, because of the formation process, as extensively discussed in Romeos et al (2009) and also in Ghias et al (2005). At successive cross-planes, the vorticity plots present only one peak and an ellipsoidal distribution around it that indicates the spatial orientation and the mutual revolution of the vortex cores.…”

Section: Resultsmentioning

confidence: 92%

“…In the formation region ( x/c = 0.3), the flow field is dictated by the pressure distribution established by the flow around the wing tips, mobilizing large masses of air and leading to the roll up of fluid sheets. Fluid streams penetrating between the wings collide, moving along a converging separatrix of the cross-plane flow topology and creating a diverging separatrix and a saddle point (Romeos et al , 2009). Along the latter, fluid from both streams is directed toward the two vortices, expanding their cores and increasing their separation distance.…”

Section: Discussionmentioning

confidence: 99%

“…The calibration and data reduction technique is based on the look-up table method, which is considered to be one of the best alternatives for processing hot-wire measurements (Van Dijk and Nieuwstadt, 2004). Further details on the design and manufacturing of the probe and the data reduction technique can be found in the study by Romeos et al (2009). Uncertainties in the measurements have been estimated as less than 4 per cent for the velocity measurement, 9 per cent for RMS values and 15 per cent for velocity gradients and vorticity.…”

Section: Experimental Configurationmentioning

confidence: 99%

“…The experimental study of co- or counter-rotating vortex systems has mainly evolved through the use of upgraded anemometry techniques such as hot-wire anemometry (HWA, Bandyopadhyay et al , 1991; Devenport et al , 1997, 1999; Bertenyi and Graham 2007; Romeos et al , 2009) and Particle Image Velocimetry (PIV, Jacob, 1998; Meunier and Leweke, 2005; Jacquin et al , 2005; Leweke et al , 2001). Cerretelli and Williamson (2003) suggested a mechanism associated with the interaction and merging process for a pair of co-rotating vortices.…”

Section: Introductionmentioning

confidence: 99%

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Co-rotating vortex interaction

Romeos

Giannadakis

Perrakis

2016

Aircraft Eng & Aerospace Tech

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Purpose The purpose of this paper is to study the structure and dynamic development of a pair of co-rotating trailing vortices, during their formation, interaction and merging, using detailed experimental measurements of the velocity and vorticity fields. Design/methodology/approach The vortices were generated using two half wings (NACA0030) positioned at equal and opposite angles of attack at the entrance of the test section of an open-circuit, subsonic, wind tunnel. Velocity vector measurements were obtained at Rec = 133,000, on cross-plane grids at several distances from the trailing edges of the wings, using an in-house developed four-sensor hot wire anemometer probe. Findings The results include cross-plane contour plots of the mean and fluctuating velocity as well as mean vorticity fields. Each of these variables is affected in a different way, providing complementary information on the development of the flow field. After shedding, the two vortices are swept along the stream-wise direction and spiral around each other, thereby developing a braid of two vortices, which then deforms the external flow field. Gradually, the interaction with the external flow field links both vortices together until the final merging and the formation of a new stable linear vortex emerges. Practical implications Trailing vortices have been rendered particularly important during the past decades, because of increasing traffic density of very heavy aircrafts and several plane “incidents”, which were attributed to the action of the vortex wake. Originality/value The presented results provide information on the evolution and merging of a pair of vortices formed by a closely spaced differential wing configuration. The vortices interact almost immediately after shedding as expected in flap–flap or flap–wing vortices interaction.

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Section: Resultsmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Experimental Configurationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Co-rotating vortex interaction

Romeos

Giannadakis

Perrakis

2016

Aircraft Eng & Aerospace Tech

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“…Other complicated designed multi sensors can provide information about the velocity-vorticity fields (e.g. Cavo et al, 2007, Romeos et al, 2009.…”

Section: Measuring Velocity Componentsmentioning

confidence: 99%

Turbulent rectangular jets

Alnahhal¹

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Greek iii List of symbols iv List of figures v List of tables vi 3. Review 3.1 Literature review 4. Experimentation 4.1 Experimental Set-up 4.1.1 Nozzle exit 4.1.2 Settling chamber 4.1.3 Blower 4.1.4 Endplates and sidewalls 4.2 Hot wire anemometry 4.2.1 Constant temperature hot-wire anemometry (CTA) 4.2.1.1 Working principle 4.2.1.2 Noise 4.2.1.3 Advantages of hot wire anemometry technique 4.2.1.4 Disadvantages of hot wire anemometry technique 4.2.1.5 Selection of hot wire sensors 4.2.1.6 Calibration of hot wire anemometer 4.2.1.7 Measuring velocity components 4.2.1.8 Specifications of the hot wire anemometry system and experimental conditions of the present investigation 4.2.1.9 Experimental uncertainty 4.3 Experimental procedure 1. jet with no endplate and no sidewalls, NENS, 2. jet with endplate and no endplate, WENS, 3. jet without endplate and with sidewalls, NEWS and 4. jet with endplate and with sidewalls, WEWS,have been measured, with x-sensor hot wire anemometry, up to an axial distance of 35 D under identical inlet conditions. Centreline measurements for the four configurations have been collected for three Reynolds number, Re D =10,000, 20,000 and 30,000. For Re D =20,000 measurements in the transverse direction were collected at 13 different downstream locations in the range of x= (0, 1, 2, 2.5, 3, 4, 5, 10, 15, 20, 25, 30 and 35) nozzle widths.The jet with no endplate and no sidewalls (NENS) and the jet with endplate and no sidewalls (WENS) produce nearly similar mean and turbulent velocity profiles indicating insignificant effect of the endplates on their development in the absence of the sidewalls. At Re=20,000, larger mean streamwise velocity values were observed at the edges of the jets (NEWS or WEWS) at distances from nozzle in the range of x/D=3-30 whereas the presence of the endplate has an insignificant effect.The presence or absence of sidewalls is also key factor determining the distributions of the lateral mean velocity component. The presence of sidewalls is associated with lower outward velocities within the edges of the jets and higher inward ones outside the edges. The absence of sidewalls makes the presence of the endplate insignificant and the lateral velocity attains outside the edges low negative values of almost the same level in both cases (NENS, WENS) The presence of an endplate has again some significance only when the sidewalls are present alleviating their effect.

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In situ calibration of four-wire hot-wire probes for atmospheric measurement

Singha

Sadr

2013

Experimental Thermal and Fluid Science

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

Cited by 6 publications

References 65 publications

Co-rotating vortex interaction

Co-rotating vortex interaction

Turbulent rectangular jets

In situ calibration of four-wire hot-wire probes for atmospheric measurement

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