Turbulence measurements in the near field of a wingtip vortex

  • 1.43 MB
  • 9806 Downloads
  • English

National Aeronautics and Space Administration, Ames Research Center, National Technical Information Service, distributor , Moffett Field, Calif, [Springfield, Va
Turbulent flow, Near fields, Wing tips, Vortices, Wind tunnel tests, Flow measurement, Stress tensors, Reynolds s
StatementJim Chow, Greg Zilliac, Peter Bradshaw.
SeriesNASA technical memorandum -- 110418.
ContributionsZilliac, Greg., Bradshaw, P. 1935-, Ames Research Center.
The Physical Object
FormatMicroform
Pagination1 v.
ID Numbers
Open LibraryOL17834421M
OCLC/WorldCa39705632

Mean Flow and Turbulence Measurements in the Near Field of a Fighter Aircraft Wing-Tip Vortex at High Reynolds Number and Transonic Flow Conditions The wing-tip vortex was generated by a rigid 6% scale wind tunnel model of the F/A fighter aircraft.

The model was supported by a roof-mounted sting (Figure 1). The mounting bracket permitted Author: Fenella de Souza, Ben H.K.

Lee. Mean and Turbulence Measurements in the Near Field of a Wingtip Vortex. An experimental study on the interaction between free-stream turbulence and a wing-tip vortex in the near-field.

Aerospace Science and Technology, Vol. The Effect of Streamtube Contraction on the Characteristics of a Streamwise by:   Measurements in the near-field of a turbulent wingtip vortex.

Download Turbulence measurements in the near field of a wingtip vortex PDF

Turbulence Measurements inside Blade Tip Vortices Using Dual-Plane Particle Image Velocimetry. Journal of the American Helicopter Society, Vol.

55, No. Turbulent Tip Vortex Measurements Using Dual-Plane Stereoscopic Particle Image Velocimetry. Turbulence Measurements in the Near Field of a Wingtip Vortex The roll-up of a wingtip vortex, at Reynolds number based on chord of million was studied with an emphasis on suction side and near wake measurements.

The research was conducted in a 32 in. x 48 in. low-speed wind tunnel. The half-wing model had a semi-span of 36 in. a chord of 48 in. and a rounded tip. Turbulence measurements in the near field of a wingtip vortex (OCoLC) Material Type: Document, Government publication, National government publication, Internet resource: Document Type: Internet Resource, Computer File: All Authors / Contributors: Jim Chow; Gregory G Zilliac; P Bradshaw; Ames Research Center.

A Reynolds stress turbulence model using vorticity confinement was used to compute the vortex in the near-field and experimental measurements were taken with a five-hole probe and x-wire anemometer. WING-TIP VORTEX EVOLUTION IN TURBULENCE Planar and stereo particle image velocimetry measurements were conducted of a wing-tip vortex decaying in free-stream turbulence in order to understand the evolution of a vortex and its decay mechanism.

The vortex decayed faster in the presence of turbulence. The flow in the cross-flow separation region of a prolate spheroid at 10 deg angle of attack, Re L = × 10 6, was investigated using a novel, miniature, 3-D, fiber-optic Laser Doppler Velocimeter (LDV).The probe was used to measure three simultaneous, orthogonal velocity components from within the model, from approximately y + = 7 out to the boundary layer edge.

J.S. Chow, G.G. Zilliac, P. BradshawMean and turbulence measurements in the near field of a wingtip vortex AIAA J., 35 (10) (), pp. Winglets and wingtip fences also increase efficiency by reducing vortex interference with laminar airflow near the tips of the wing, by 'moving' the confluence of low-pressure (over wing) and high-pressure (under wing) air away from the surface of the wing.

Wingtip vortices create turbulence, originating at the leading edge of the wingtip and. adshelp[at] The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A.

Details Turbulence measurements in the near field of a wingtip vortex EPUB

The structure and development of a wing-tip vortex - Volume - William J. Devenport, Michael C. Rife, Stergios I. Liapis, Gordon J. Follin P. Turbulence measurements in the near-field of a wingtip vortex. ASME Forum on Turbulence in Complex Flows, Chicago IL, Nov.

6– Ciffone, D. Correlation for estimating vortex. Turbulence measurements in the near-field of a wingtip vortex. NASA Tech MemNASA.]. The aim is to assess the performance of two turbulence models which, in principle, might be seen as capable of resolving both the three dimensional boundary layer on the wing and the generation and near-field decay of the strongly accelerated vortex.

Wingtip vortices are an important phenomenon in fluid dynamics due to their complex and negative impacts. Despite numerous studies, the current understanding of the inner vortex is very limited; th. The ground proximity is known to induce an outboard movement and suppression of the wingtip vortices, leading to a reduced lift-induced drag.

Depending on the ground boundary cond. Wingtip Vortices. Today we are going to talk about Wake Turbulence and Wing Tip Vortices. Wake turbulence is best explained as a spinning mass of air, originating from the wingtips of a large heavy airliner, trailing backwards that may cause following aircraft to enter an "unusual attitude" of which recovery is doubtful.

These measurements were made in the Caltech Free-Surface Water Tunnel, using a laser-Doppler velocimeter to measure two components of velocity in the vortex wake.

Two different model planforms were tested, and measurements were made at several. The turbulent rollup of a vortex generated by a rectangular wing has been investigated. Extensive mean and turbulence measurements of the flowfield on a wingtip and in the near field have been.

A physical linked-measure is mathematically consisted of a complex scalar, a complex vector and a bi-vector and is geometrically equivalent to a vortex. When the complex scalar means mass, the complex vector implies directed momentum and the bi-vector rotates angular momentum, with using the least action principle to the linked-measure.

The principal subject of this paper is analysis and modeling of turbulent wing tip vortex flows in a far‐field region of the vortex evolution. The choice of a Reynolds stress closure (RSC) to model the vortex turbulence is shown to be indispensable for representation of the flow rotation effects on turbulence.

The principal result reported is the model–experiment comparison of the vortex. Part of the Notes on Numerical Fluid Mechanics and Multidisciplinary Design book series (NNFM, G.G., Bradshaw, P.: Mean and turbulence measurements in the near field of a wingtip vortex.

AIAA J. 35(10), – () Google Scholar. Churchfield, M.J., Blaisdell, G.A.: Numerical simulations of a wingtip vortex in the near field. Because tip vortex cavitation occurs at short distances from the wing tip, most recent works have been concerned on the very near region (less than a chord), Stinebring et al.

(), Fruman et al. (a, b, a, b, c, ) and Pauchet et al. (, ), and the intermediate region (comprised between one and ten chords.

Description Turbulence measurements in the near field of a wingtip vortex EPUB

the turbulence in the vortex. Based on this experiment, Dacles-Mariani et al (Dacles-Mariani, et al, ) conducted the numerical simulations of the wingtip vortex flow in the near field region.

The method of artificial compressibility was used to solve the. A full Reynolds stress turbulence model with a hybrid unstructured grid was used to compute the wing-tip vortex in the near field while an x-wire anemometer and five-hole probe recorded the experimental results. The mean flow of the computed vortex was in good agreement with experiment as the circulation parameter was within 6% of the.

The turbulent rollup of a vortex generated by a rectangular wing has been investigated. Extensive mean and turbulence measurements of the flowfield on a wingtip and in the near field have been completed.

Velocity fluctuation measurements show that the near-field core is not laminar. Particle image velocimetry measurements were conducted for a wing-tip vortex decaying in free-stream turbulence. The vortex exhibited stochastic collapse with free-stream turbulence present, with the breakdown initiating earlier for higher levels of turbulence.

An increased rate of decay of the. The near-wake vortex flowfield from a NACA half-wing was simulated using a fully unstructured Navier-Stokes flow solver in three dimensions at a chord Reynolds number of million and a Mach number of approximately Several simulations were performed to examine the effects of boundary conditions, mesh resolution, and turbulence scheme on the formation of wingtip vortex and its.

An experimental investigation of the wake of an Unmanned Aerial Vehicle (UAV) model using flow visualization techniques and a 3D Laser Doppler Anemometry (LDA) system is presented in this work.

Emphasis is given on the flow field at the wingtip and the investigation of the tip vortices. A comparison of the velocity field is made with and without winglet devices installed at the wingtips. Turbulence modelling in application to the vortex shedding of stalled airfoils; The computational modelling of wing-tip vortices and their near-field decay; URANS computations of shock induced oscillations over 2D rigid airfoil: Influence of test section geometry; Zonal multi-domain RANS/LES simulation of airflow over the Ahmed body.

The vortex shed from a straight rectangular wing with squared tips was investigated to identify the main mechanisms involved in the near-field roll up of the vortex. The combination of experimental measurement techniques, such as hot-wire anemometry and a five-hole pressure probe, gave great insight into the behaviour of the mean and turbulent.

The near-field (up to three chord lengths) development of a wing-tip vortex is investigated both numerically and experimentally. The research was conducted in a medium speed wind tunnel on a NACA square tip half-wing at a Reynolds number of × 10 5.A full Reynolds stress turbulence model with a hybrid unstructured grid was used to compute the wing-tip vortex in the near field while an.Wingtip vortices are circular patterns of rotating air left behind a wing as it generates lift.

One wingtip vortex trails from the tip of each wing. Wingtip vortices are sometimes named trailing or lift-induced vortices because they also occur at points other than at the wing tips.

Indeed, vorticity is trailed at any point on the wing where the lift varies span-wise (a fact described and.Wake turbulence is a disturbance in the atmosphere that forms behind an aircraft as it passes through the air.

It includes various components, the most important of which are wingtip vortices and jetwash. Jetwash refers simply to the rapidly moving gases expelled from a jet engine; it is extremely turbulent, but of short duration.