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Sunday, August 2, 2020 | History

3 edition of Measurements of a turbulent horseshoe vortex formed around a cylinder found in the catalog.

Measurements of a turbulent horseshoe vortex formed around a cylinder

Measurements of a turbulent horseshoe vortex formed around a cylinder

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  • 31 Currently reading

Published by National Aeronautics and Space Administration, Scientific and Technical Information Branch in [Washington, D.C.] .
Written in English

    Subjects:
  • Cylinders.,
  • Flow distribution.,
  • Turbulent boundary layer.,
  • Turbulent flow.,
  • Vortices.,
  • Wind tunnel tests.

  • Edition Notes

    StatementW. A. Eckerle, L. S. Langston.
    SeriesNASA contractor report -- 3986., NASA contractor report -- NASA CR-3986.
    ContributionsLangston, L. S., United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., Lewis Research Center.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL16122222M

    developed vortex system which stretches around the cylinder is referred as a horseshoe vortex system due to its shape. Schwind [1] pioneered in the study on a horseshoe vortex system upstream of a wedge placed in a wind tunnel. The periodical characteristics of the horseshoe vortex system was also noticed by Roper [2] and Dargahi [3], who used the. [1] Most of the erosion around obstacles present in alluvial streams takes place after the formation of a scour hole of sufficiently large dimensions to stabilize the large‐scale oscillations of the horseshoe vortex (HV) system. The present paper uses eddy resolving techniques to reveal the unsteady dynamics of the coherent structures present.

      With the aid of direct numerical simulation, this paper presents a detailed investigation on the flow around a finite square cylinder at a fixed aspect ratio (AR) of 4 and six Reynolds numbers (Re = 50, , , , , and ). It is found that the mean streamwise vortex structure is also affected by Re, apart from the AR value. A turbulent boundary layer approaching a local obstruction, such as when annulus wall boundary layers encounter airfoils and support struts, creates a critical problem in gas turbine engines. The slower portion of the approaching boundary layer cannot negotiate the adverse pressure gradient generated by the obstruction and consequently separates from the endwall.

    Prominent flow features associated with the formation of a scour hole around a cylinder are the necklace-like vortical structure, commonly known as the horseshoe vortex (HV), and the wake eddies shed by the cylinder. Regardless of the exact form of the bridge pier, one the main mechanisms (Baker, , , Dargahi, , ) that. ved an oscillatory behavior of the horseshoe vortex system, starting at almost constant values of Reynolds number based on the size of the obstacle. Baker () studied experimen-tally the horseshoe vortex that is formed around the base of a cylinder by a laminar boundary layer that has separated. He.


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Measurements of a turbulent horseshoe vortex formed around a cylinder Download PDF EPUB FB2

Measurements of a turbulent horseshoe vortex formed around a cylinder the flow is described using a five-hole probe and by cylinder and endwall surface static pressure measurements.

At a. Get this from a library. Measurements of a turbulent horseshoe vortex formed around a cylinder. [W A Eckerle; L S Langston; United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch.; Lewis Research Center.] -- "An experimental program was conducted to track the variation in soot loading in a generic gas turbine combustor.

Get this from a library. Measurements of a turbulent horseshoe vortex formed around a cylinder. [Wayne Alan Eckerle; Thomas James Rosfjord; United.

Measurements of a Turbulent Horseshoe Vortex Formed Around a Cylinder w. Eckerle United Technologies Research Center East Hartford, Connecticut L.

Langston University of Connecticut Storrs, Connecticut Prepared for Lewis Research Center under Grant NSG NI\S/\ National Aeronautics and Space Administration Scientific and Technical.

The horseshoe vortex formed around the base of a cylinder by a separating turbulent boundary layer has been investigated experimentally.

Smoke- and oil-flow visualization has enabled the nature of the horseshoe vortex system to be described. Pressure distributions beneath horseshoe vortex systems have been by: Numerical predictions of the horseshoe vortex formed around an endwall mounted cylinder, using the Reynolds averaged, steady, incompressible Navier-Stokes equations, are compared to experimental measurements.

The flow is fully turbulent with a Reynolds number ofbased on inlet velocity and cylinder diameter. An existing computer code, INS3D, was originally applied to compute this flow.

The Reynolds averaged Navier Stokes equations have been numerically solved for the case of a turbulent horseshoe vortex flow around an endwall mounted cylinder. Two different models were used, one grid containingmesh points, and then a larger grid withpoints. When the approach flow encounters a cylinder, the incoming boundary layer separates from the upstream bed due to an adverse pressure gradient imposed by the obstacle, resulting in a so-called turbulent horseshoe vortex (THV) formed in front of the cylinder.

The THV is highly relevant to many applications in hydrodynamics and aerodynamics. vortex formed around the base of a cylinder by a separating laminar boundary layer, and found that both steady and unsteady vortex systems exist.

On the other hand, experimental investigations on Strouhal numbers and the system of the vortex shed behind a bluff body attached to a plane wall have also been reported by several authors. Due to a strong acceleration along the streamlines, a region of relatively small turbulent kinetic energy is found between the horseshoe vortex and the cylinder.

When passing under the horseshoe vortex, the upstream-directed jet formed by the deflected downflow undergoes a deceleration which gives rise to a strong production of turbulent.

A turbulent horseshoe vortex (HV) system around a wall-mounted cylinder in open channel is characterized by random variations in vortex features and an abundance of vortex interactions. The turbulent HV system is responsible for initiating the local scour process in front of the cylinder.

The evolution of the turbulent HV system is investigated statistically and quantitatively with time. Measurements of a turbulent horseshoe vortex formed around.

Measurements of a turbulent horseshoe vortex formed around a cylinder vortex system in front of and around a single large-diameter right cylinder centered between the sidewalls of a wind tunnel. Surface flow visualization and surface static pressure measurements as well as extensive mean velocity and pressure measurements in and around the.

The turbulent horseshoe vortex (HV) system and the near-wake flow past a circular cylinder mounted on a flat bed in an open channel are investigated based on the results of eddy-resolving simulations and supporting flow visualizations. Of particular interest are the changes in the mean flow and turbulence statistics within the HV region as the necklace vortices wrap around the cylinder’s.

A turbulent horseshoe vortex (HV) system around a wall-mounted cylinder in open channel is characterized by random variations in vortex features and an abundance of vortex interactions. three planes around circular cylinder. The velocity measurements fell in the vertical range of D to 2D from the bed in which it is above the horseshoe vortex activity region.

The horseshoe vortex activity region is always under D as observed from the researches that studied the phenomenon [1, 2, 10]. The substantial adverse pressure gradient experienced by a turbulent boundary layer while approaching an endwall-mounted twisted turbine blade and caused the impending flow to separate.

constant size. Behind the dome, arched vortex tubes form and are shed individually or coalesce before shedding depending on a critical Reynolds number of 2, Using split-fiber probes and hot-wire anemometers Tavakol et al. [6] investigated the turbulent flow around a dome by obtaining.

The time-averaged kinematical and dynamical characteristics of the junction vortex system in front of a symmetrical obstacle are systematically analyzed for both laminar and turbulent flows.

A wide set of experimental and numerical results from the literature is coordinated in nondimensional form together with some new computational data.

The main flow features around a vertical cylindrical pile exposed to a steady current on a plane bed are the horseshoe vortex formed in front of the pile, the lee-side vortices (usually in the form of vortex shedding), contracted streamlines around the sides of the pile and the down-flow in front of the pile due to deceleration of the flow.

2. Previous Work on Turbulent Flows Past Surface‐Mounted Obstacles The Dynamics of the Turbulent Horseshoe Vortex on a Flat Fixed Bed [11] A surface‐mounted obstacle in a turbulent boundary layer induces adverse pressure gradients, causing the for-mation of the dynamically‐rich THV system in the junction of the obstacle with the wall.Details of the horseshoe vortex formation around a cylinder were studied to determine the flow parameters that affect the flow separation in front of the cylinder.

An experimental setup consisting of a circular cylinder vertically mounted on the floor of the wind tunnel test section was assembled. Visualization of the turbulent junction flow upstream of a bluff body.