LASER VELOCIMETRY SEED PARTICLES WITHIN COMPRESSIBLE, VORTICAL FLOWS

The ability of seed particles to penetrate and accurately track vortices is of critical importance to the analysis of laser velocimetry (LV) measurements within these flow structures. In applying a particle equation of motion to vortical flowfields which extend into the supersonic, compressible regime, two approaches are considered. First, an ideal, potential vortex is developed for a compressible flowfield. As an aid to the design and analysis of vortical flowfield surveys over a wide range of independent parameters, this model is used to plot the time and position at which any particle starting at rest within a vortex will begin to track the flow velocity within 3% error. As a specific application, the potential vortex is then used to estimate the dynamic bias of LV measurements taken within a vortex shed from a 75-deg delta wing at 20 deg angle of attack in a Mach 1.9 supersonic flow. The second approach uses a computationally derived Navier-Stokes flowfield solution in place of the potential vortex model. The computationally flowfield method predicts that accurate LV measurements within the delta wind flowfield require seed particles no larger than 0.1-0.2 mu m in diameter, and defines the unseeded inner vortex core region. Both approaches show an increase in velocity bias which is nearly proportional to particle diameter, stressing the need for a monodisperse seed of known size to resolve particle bias in complex flows.

  • Supplemental Notes:
    • AIAA J, v 30 n 2, Feb 1992, p 376 [8 p, 11 ref, 1 tab, 14 fig]
  • Authors:
    • Maurice, M S
  • Publication Date: 1992

Language

  • English

Subject/Index Terms

Filing Info

  • Accession Number: 00716246
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Feb 28 1996 12:00AM