rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Experimental analysis of the vorticity and turbulent flow dynamics of a pitching airfoil at realistic flight (helicopter) conditions
  name:
    name part: Sahoo, Dipankar
    name part: 1978-
    role:
      role term: creator
  name:
    name part: Bowersox, Rodney D. W.
    role:
      role term: thesis advisor.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2008
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: electronic
    form: remote
  abstract: Improved basic understanding, predictability, and controllability of vortex-dominated and unsteady aerodynamic flows are important in enhancement of the performance of next generation helicopters. The primary objective of this research project was improved understanding of the fundamental vorticity and turbulent flow physics for a dynamically stalling airfoil at realistic helicopter flight conditions. An experimental program was performed on a large-scale (C = 0.45 m) dynamically pitching NACA 0012 wing operating in the Texas A&M University large-scale wind tunnel. High-resolution particle image velocimetry data were acquired on the first 10-15% of the wing. Six test cases were examined including the unsteady (k>0) and steady (k=0) conditions. The relevant mechanical, shear and turbulent time-scales were all of comparable magnitude, which indicated that the flow was in a state of mechanical non-equilibrium, and the expected flow separation and reattachment hystersis was observed. Analyses of the databases provided new insights into the leading-edge Reynolds stress structure and the turbulent transport processes. Both of which were previously uncharacterized. During the upstroke motion of the wing, a bubble structure formed in the leading-edge Reynolds shear stress. The size of the bubble increased with increasing angle-of-attack before being diffused into a shear layer at full separation. The turbulent transport analyses indicated that the axial stress production was positive, where the transverse production was negative. This implied that axial turbulent stresses were being produced from the axial component of the mean flow. A significant portion of the energy was transferred to the transverse stress through the pressure-strain redistribution, and then back to the transverse mean flow through the negative transverse production. An opposite trend was observed further downstream of this region.
  note: by Dipankar Sahoo.
  note: "Major Subject: Aerospace Engineering"
  note: Title from author supplied metadata (automated record created on Oct. 13, 2008.)
  note: Vita.
  note: Abstract.
  note: Electronic resource.
  note: Mode of access: World Wide Web.
  note: System requirements: World Wide Web access and Adobe Acrobat Reader.
  note: Ph. D. Texas A&M University 2008.
  note: Includes bibliographical references.
  note: Text (Ph. D.).
  subject:
    topic: Major Aerospace Engineering
  subject:
    topic: NACA 0012
  subject:
    topic: PIV
  subject:
    topic: Reynolds Shear Stress
  subject:
    topic: Time Scale
  subject:
    topic: Turbulent Flow Field
  subject:
    topic: Production of Turbulence
  subject:
    topic: Dynamic Stall
  identifier: http://hdl.handle.net/1969.1/85893
  record info:
    record content source: TXA
    record creation date: 090309
    record change date: 20151110080414.0
    record identifier: in00002484665