Organized nature of a turbulent trailing vortex

Bandyopadhyay, Promode R.; Ash, Robert L.; Stead, Daniel J.

doi:10.2514/3.10784

Cited by 68 publications

(44 citation statements)

References 14 publications

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“…Similar to the earlier study by Bandyopadhyay et al (1991) was an experimental study of a trailing vortex immersed in an external grid-generated turbulence field carried out by Beninati and Marshall (2005). They sought to add to the knowledge of how a vortex interacts with external turbulence, citing a lack of literature on the problem (despite its importance) as motivation.…”

Section: Experimental Investigations Of Wing-tip Vortices In the Nearmentioning

confidence: 93%

“…A square tip wing was found to produce a secondary vortex, which was eliminated by the introduction of a round lateral tip. Bandyopadhyay et al (1991) carried out the first investigation that sought to identify organized motions in a trailing vortex and understand their role in the production and dissipation of turbulence in a vortex up to 40 chord lengths downstream. The vortex was shed from a flow aligned cylinder and two oppositely loaded aerofoils in a low Reynolds number (15 × 10 3 to 25 × 10 3 ) flow subjected to a range of free-stream turbulence (0.032% to 1.48%).…”

Section: Literature Reviewmentioning

confidence: 99%

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Numerical and experimental investigation of the mean and turbulent characteristics of a wing-tip vortex in the near field

O’Regan

Griffin

Young

2014

Proceedings of the Institution of Mechanical Engineers, Part G:

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Section: Experimental Investigations Of Wing-tip Vortices In the Nearmentioning

confidence: 93%

Section: Literature Reviewmentioning

confidence: 99%

Numerical and experimental investigation of the mean and turbulent characteristics of a wing-tip vortex in the near field

O’Regan

Griffin

Young

2014

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Velocity and pressure field measurements in the wake of an aircraft model are a valuable resource in predicting the performance characteristics of the aircraft (Spalart 1998b;Rossow 1999), as well as a means to investigate the more fundamental nature of vortex flows (see, for example, Bandyopadhyay et al (1991) and Phillips & Graham (1984)). However, single-point scans of vortex flows (such as the hot-wire and multi-hole pressure probe data of Beninati & Marshall (2005), Birch et al (2004), Birch & Lee (2005), Chow et al (1997) and Dacles-Mariani et al (1995), to list but a few) will tend to underpredict vortex strength owing to the smoothing effect of vortex 'meandering', or the random, low-frequency modulation in the trajectory of the vortex centre.…”

Section: Introductionmentioning

confidence: 99%

Tracer particle momentum effects in vortex flows

Birch¹,

Martin²

2013

J. Fluid Mech.

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The measurement of vortex flows with particle-image velocimetry (PIV) is particularly susceptible to error arising from the finite mass of the tracer particles, owing to the high velocities and accelerations typically experienced. A classical model of Stokes-flow particle transport is adopted, and an approximate solution for the case of particle transport within an axisymmetric, quasi-two-dimensional Batchelor q-vortex is presented. A generalized expression for the maximum particle tracking error is proposed for each of the velocity components, and the importance of finite particle size distributions is discussed. The results indicate that the tangential velocity component is significantly less sensitive to tracking error than the radial component, and that the conventional particle selection criterion (based on the particle Stokes number) may result in either over-or under-sized particles for a specified allowable error bound. Results were demonstrated by means of PIV measurements carried out in air and water using particles with very different properties.

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“…Analogous results may be found for the variance of the cross-velocity, not reported here. It is then fundamental to understand whether this unsteadiness in correspondence to the vortex core is the result of a real turbulent activity or, as suggested by Bandyopadhyay et al (1991), Devenport et al (1996) and Chow et al (1997), the vortex core is a relaminarization region, which far downstream is characterized by fluctuations at relatively small frequencies that may be ascribed to vortex wandering, i.e., to the oscillation of vorticity structures with dimensions comparable to the vortex core itself. From the spectral analysis of the velocity signals, no definite conclusion could be drawn; in effect, by approaching the vortex center along a radial direction, both the Fourier and wavelet velocity spectra showed an energy increase extended to the whole frequency domain; this behavior was especially enhanced for the cross-velocity.…”

Section: Flow Field Analysismentioning

confidence: 99%

Correction of wandering smoothing effects on static measurements of a wing-tip vortex

2008

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Wandering is a typical feature of wing-tip vortices and it consists in random fluctuations of the vortex core. Consequently, vortices measured by static measuring techniques appear to be more diffuse than in reality, so that a correction method is needed. In the present paper statistical simulations of the wandering of a Lamb-Oseen vortex are first performed by representing the vortex core locations through bi-variate normal probability density functions. It is found that wandering amplitudes smaller than 60% of the core radius are well predicted by using the ratio between the RMS value of the mean cross-velocity and its slope measured at the mean vortex center. Furthermore, the principal axes of wandering can be accurately evaluated from the opposite of the cross-correlation coefficient between the spanwise and the normal velocities measured at the mean vortex center. The correction of the wandering smoothing effects is then carried out through four different algorithms that perform the deconvolution of the mean velocity field with the probability density function that represents the wandering. The corrections performed are very accurate for the simulations with wandering amplitudes smaller than 60% of the core radius, whereas errors become larger with increasing wandering amplitudes. Subsequently, the whole procedure to evaluate wandering and to correct the mean velocity field is applied to static measurements, carried out with a fast-response five-hole pressure probe, of a tip vortex generated from a NACA 0012 half-wing model. It is found that the wandering is predominantly in the upward-outboard to downward-inboard direction. Furthermore, the wandering amplitude grows with increasing streamwise distance from the wing, whereas it decreases with increasing angle of attack and free-stream velocity.

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Organized nature of a turbulent trailing vortex

Cited by 68 publications

References 14 publications

Numerical and experimental investigation of the mean and turbulent characteristics of a wing-tip vortex in the near field

Numerical and experimental investigation of the mean and turbulent characteristics of a wing-tip vortex in the near field

Tracer particle momentum effects in vortex flows

Correction of wandering smoothing effects on static measurements of a wing-tip vortex

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