Applied Scientific Research

, Volume 56, Issue 2, pp 157–179

3-D scanning-particle-image-velocimetry: Technique and application to a spherical cap wake flow

  • Ch. Brücker
Article

DOI: 10.1007/BF02249379

Cite this article as:
Brücker, C. Appl. Sci. Res. (1996) 56: 157. doi:10.1007/BF02249379

Abstract

A 3-D time-resolving and whole-volume Digital-Particle-Image-Velocimetry (DPIV) technique based on the concept of a scanning light-sheet is presented and applied here to the 3-D transient wake phenomena in the spherical cap wake flow. The technique uses a scanning light-sheet for rapid sampling of the flow in depth and a two-camera recording system for stereoscopic 3-D DPIV. Application of a correlation technique in combination with a calibration yields, aside from the correct in-plane displacement, also the out of plane component and thus the total velocity vectors within the planes of the scanning light-sheet. With a high scanning rate in comparison to the characteristic time scales the method provides the 3-D velocity field in space and time. Through the use of conventional video-techniques the temporal evolution of the complete velocity and vorticity field can be obtained quantitatively from experiments. This is demonstrated for the 3-D starting flow around a spherical cap at Re=300. During the starting process, the flow in the wake evolves into a spherical vortex ring where the velocity distribution is very close to the theoretical solution of the Hill-type vortex. Later on, the Hill-type vortex ring deforms and the flow changes from a rotational symmetric stage to a planar symmetric flow with a double-threaded vortical structure which consists of two counter-rotating streamwise vortices similar to the ones observed in sphere wake flow.

Key words

3-D PIV scanning light sheet spherical cap wake sphere wake Hill-vortex transitional flow 

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Ch. Brücker
    • 1
  1. 1.Aerodynamisches InstitutRWTH AachenAachenGermany

Personalised recommendations