Coherent detection in Doppler global velocimetry: a simplified method to measure subsonic fluid flow fields

The principles of an entirely new method to demodulate Doppler signals in Doppler global velocimetry (DGV) are discussed. The method makes use of coherent detection and streak imaging to record both temporal and spatial information on a single image. The method retains the simplicity of the basic DGV technique yet increases its applicability to subsonic flow regimes. The combination of a straightforward optical configuration and the ability to collect large data sets efficiently make this technique particularly useful in high-cost experimental facilities such as wind-tunnel testing where large quantities of data must be collected in a relatively short time period.