In this paper, a shearography approach is used to encode flow field density measurements. The fringes are projected through the flow field and automatically analyzed using the Fast Fourier Transform method. The subsequent `wrapped' phase map is `unwrapped' using the largely noise immune Minimum Spanning Tree technique. This allows the flow field to be solved despite the presence of discontinuities such as shocks. This technique was applied to the results made on a 2D transonic windtunnel at Rolls Royce, Derby where whole field measurements were made. The subsequent fringe patterns were each solved by the automatic fringe analysis technique on a Sparc-5 Sun system. The shock structures were observed to be the same as those revealed by earlier flow visualizations. The density measurements correspond well to previous holographic measurements.

Date Published: 19 July 1996
PDF: 12 pages
Proc. SPIE 2861, Laser Interferometry VIII: Applications, (19 July 1996); doi: 10.1117/12.245158

Published in SPIE Proceedings Vol. 2861:
Laser Interferometry VIII: Applications
Ryszard J. Pryputniewicz; Gordon M. Brown; Werner P. O. Jueptner, Editor(s)