Recent Applications of Three-Dimensional Doppler-Global Velocimetry in Turbo-Machinery

Abstract

A Doppler global velocimetry (DGV) system optimised for time-averaged three component velocity measurements has been applied in two situations. The system uses a single viewing direction in conjunction with three different illumination directions. A frequency-stablised Ar+-laser (sn<1 MHz) and a pair of Peltier-cooled CCD’s with 12-bit dynamic range allow a measurement resolution better than 1 m/s. A modified version of the hardware was used to map the cross-section of an engine inlet within a 1:10 scale aircraft model. In order to meet spatial constraints within the model, miniature light sheet devices and a flexible endoscope were necessary to obtain the data. In another application time-average volumetric, three-component velocity data was obtained in a double-staged, ‘cold’ combustion chamber by translating the light sheet plane at 2 mm increments. More recent efforts directed toward obtaining phase-averaged DGV data are also presented.