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3 edition of Visualization of secondary flow development in high aspect ratio channels with curvature found in the catalog.

Visualization of secondary flow development in high aspect ratio channels with curvature

Visualization of secondary flow development in high aspect ratio channels with curvature

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Published by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC], [Springfield, Va .
Written in English

    Subjects:
  • Flow visualization.,
  • Turbulence.,
  • Curvature.

  • Edition Notes

    StatementMichael L. Meyer and James E. Giuliani.
    SeriesNASA technical memorandum -- 106658
    ContributionsGiuliani, James E., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL17112881M

      Example of creeping-flow of the sPTT fluid with ɛ = and β = 1 / 9 in a cross-slot channel with normalized aspect ratio A R n = Flow is (a, b) steady symmetric at D e = and (c, d) steady asymmetric at D e = The issue was resolved in part by a flow visualization study of the secondary flow development in a curving high aspect ratio (AR = 5) channel.3 The study showed qualitatively that the secondary vortex pair developed. But because the study was limited to low turbulent Reynold's numbers and the strength of the secondary flow was not quantified.

      Ligrani P M and Niver R D Flow visualization of Dean vortices in a curved channel with 40 to 1 aspect ratio, Phys. Fluids 31 Crossref Google Scholar Ligrani P M, Finlay W H, Fields W A, Fuqua S J and Subramanian C Features of wavy vortices in a curved channel from experimental and numerical studies, Phys. Fluids A 4 A detailed experimental study of flow in a rectangular sudden expansion using both active and passive forcing techniques has been made. The configuration consists of a 2: 1-aspect-ratio rectangular channel which undergoes a sudden expansion such that the backward-facing step height (h) is uniform, and equal to the minor side of the inlet channel.

    Particles in finite-inertia confined channel flows are known to segregate and focus to equilibrium positions whose number corresponds with the fold of symmetry of the channel’s cross section. The addition of curvature into channels presumably modifies these equilibrium inertial focusing positions, because of the secondary flow induced in curved channels. , aspect ratio 1 ≤ Ar ≤ 8 and Grashof number Gr ≤ ≤ It has been illustrated that the onset of Dean instability would vary with the duct aspect ratio and curvature ratio while the application of wall heat flux radically changes the flow patterns. Subsequently, other numerical work such as those.


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Visualization of secondary flow development in high aspect ratio channels with curvature Download PDF EPUB FB2

The results of an experimental project to visually examine the secondary flow structure that develops in curved, high aspect-ratio rectangular channels are presented. The results provide insight into the fluid dynamics within high aspect ratio channels. A water flow test rig constructed out of plexiglass, with an adjustable aspect ratio, was used for these experiments.

Results were obtained Cited by: 5. Get this from a library. Visualization of secondary flow development in high aspect ratio channels with curvature. [Michael L Meyer; James E Giuliani; United States. National Aeronautics and. A water flow test rig constructed out of plexiglass, with an adjustable aspect ratio, was used for these experiments.

Results were obtained for a channel geometry with a hydraulic diameter of mm ( in.), an aspect ratio ofand a hydraulic radius to curvature radius ratio of Author: James E. Giuliani and Michael L. Meyer. But the effects of aspect ratio on secondary flow development have not been experimentally studied.

To provide some insight into the effects of channel aspect ratio on secondary flow and to qualitatively provide anchoring for the numerical codes, a flow visualization experiment was initiated at the NASA Lewis Research : Michael L. Meyer, James E. Giuliani. Flow within an alluvial channel bend is significantly affected by channel geometry, including curvature ratio (bend radius/channel width, R / B) and aspect ratio (channel width/flow depth, B / H).High curvature bends (R / B ≤ 3) can experience substantially more erosion than milder curvature study employs a three-dimensional Reynolds-Averaged Navier-Stokes (RANS) model to Cited by: Results from a flow visualization study of Dean vortex flow are presented.

These were obtained over a range of Dean numbers from 40 to using a transparent channel with mild curvature, an aspect ratio of 40 to 1, and an inner to outer radius ratio of   In this work, we investigate these secondary flows in low aspect ratio spiral rectangular microchannels and define their development with respect to the channel aspect ratio.

Flows in channels with streamwise curvature and spanwise rotation are visualized in terms of end-view near the exit of the test sections through injecting smoke into the flows.

Two test sections are used, i.e. the rectangular channels with the aspect ratio of respectively. The work focuses on visualization of Dean and Coriolis vortices under the effects of secondary instabilities and.

Secondary flows were experimentally examined in three 90° curved ducts with square cross sections and different radii of curvature.

Dean numbers were from × 10 4 to × 10 4 and radius ratios of, and were used. Streak photography flow measurements were made and general developing secondary flow patterns were studied for three cross sections in each bend: the.

Examples are shown for the following secondary flow phenomena: (1) laminar entry flow in a curved pipe, (2) flow in a degree sharp turn of square duct, (3) instability phenomena in a curved rectangular channel with aspect ra (4) relaminarization in a helical pipe, and (5) pitch effect on secondary flow in helical pipes.

Visualization of secondary flow development in high aspect ratio channels with curvature Turbulence in cooling channels of rocket engines: Large Eddy Simulations Jan Measurements for developing turbulent flow in a high aspect ratio (AS = 6), small area ratio (AR = 2), 90 deg curved diffuser have been made.

Mean velocities, static and total pressures, and turbulence intensities were measured using a three-hole pressure probe and a hot-wire probe. Flow visualization studies were also made using a tuft probe. The observed sequential development of secondary Dean vortices depends upon the Dean number in the spiral microchannel, as well as the radius of curvature, and the aspect ratio of the channel.

Additionally, this vortex development is consistent with the macroscale investigations reported by Sugiyama et al. Effect of aspect ratio on developing and developed narrow open channel flow with rough bed Minakshee Mahananda, a Prashanth Reddy Hanmaiahgari, a b Ram Balachandar * b a Department of Civil Engineering, Indian Institute of Technology Kharagpur, KharagpurIndia.

The paper presents an experimental study of heat/mass transfer coefficient in aspect ratio smooth channels with non-uniform cross-sections. Curved leading and trailing edges are studied, for two curvatures of m −1 ( in −1) and m −1 ( in −1) and for two different curvature.

Ko and Wu () investigated secondary flow instability induced by turbulent forced convection in curved rectangular ducts with Ar =1 and 4. It is noted that the aforementioned studies focused on curved ducts with constant curvature and aspect ratio. Two test sections were used; rectangular channels with aspect ratios of 1 and The focus was on Dean and Coriolis vortices under the effects of secondary instabilities and flows in the region with a low negative rotation speed and a relatively high rotation speed.

Le Guer and H. Peerhossaini, “ Order breaking in Dean flow,” Phys. Fluids A 3, (). Google Scholar Scitation; 3. Ligrani and R. Niver, “ Flow visualization of Dean vortices in a curved channel with 40 to 1 aspect ratio,” Phys. Flu (). Google Scholar Scitation; 4. The effects of secondary flow are introduced by changing the aspect ratio of rotating channels.

Moore [11] examined the velocity profiles in a duct with aspect ratio and 7 1 3: 1 aspect ratio. Two test sections are used, i.e.

the rectangular channels with the aspect ratio of respectively. The work focuses on visualization of Dean and Coriolis vortices under the effects of secondary instabilities and flows in the region with a relatively high rotation speed.

of anisotropy in narrow open channel flow is less than wide open channel in flows. Finally, a linear regression model i s proposed to predict flow development length in narrow open channel flows with a rough bed.

Keywords: turbulence, narrow open channel, aspect ratio, developing flow, fully develop flow, flow development length. Page 2 of The micromixer, which has a rotor with a curved channel, is studied experimentally. The secondary flow in a curved channel of rectangular cross-section is investigated using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) methods.

Two walls of the channel (the inner and top walls) rotate around the center of curvature and a pressure gradient is imposed in the direction of.The development of laminar flow in a ° section of a curved square duct (R/d = ) was studied by laser-Doppler anemometry (LDA).The streamwise flow-velocity component V ϕ and the secondary flow component V r were measured as a function of Dean number and of the azimuthal angle ϕ.

The development of the streamwise flow component was found to be connected with a strong .