Development and Testing of the Virginia Tech Doppler Global Velocimeter (DGV)

Abstract

A new laser based flow interrogation system, capable of simultaneous measurement of planar three-component velocity data, was constructed and tested. The Virginia Tech Doppler Global Velocimeter (DGV) system was designed for use in the Virginia Tech Stability Wind Tunnel as a tool for investigating complex three-dimensional separated flow regions. The systems was designed for robustness, ease of use, and for acquisition of low uncertainty velocity data. A series of tests in the Stability Tunnel were conducted to determine the how well the new DGV system met these goals. Extensive calibration tests proved the system is capable of measuring the frequency shifts of scattered laser light, and therefore velocity. However, equipment failures and inadequate flow seed density prevented accurate velocity measurements in the separated wake region behind a 6:1 prolate spheroid. Detailed uncertainty analysis techniques demonstrated that, under the proper conditions, the system is capable of making velocity measurements with approximately +/- 2m/s uncertainty.