Development of a planar three-component velocimeter using Doppler global velocimetry (DGV) and PIV

Doppler global velocimetry (DGV) is a planar velocity measurement technique, which is based on the determination of the Doppler shift of laser light scattered off particles by using a molecular filter. Currently a pulsed Doppler global velocimeter is being constructed at the Institute of Fluid Dynamics. An out-of-plane component of each velocity vector in the laser-illuminated plane is obtained by that configuration. The experimental setup is extended so as to measure the in-plane component of those velocity vectors by using particle image velocimetry (PIV). Thus, a measurement system is being developed which is capable of obtaining three components of the velocity vectors located in a plane by using one single camera system. A velocimeter based on pulsed DGV consists of a long-pulse laser for the flow illumination, an image acquisition system and the molecular filter cell. The specifications of each single component have a major effect on the overall system performance. Therefore the technical specifications of all velocimeter components have been evaluated experimentally. Evaluation data are presented in this report. First results of calibration measurements are also shown and an outlook on upcoming steps of the system development is given.