Working principle and experimental results for a differential phase-Doppler technique

By replacing the two detectors of a standard phase-Doppler anemometer (PDA) with a charge coupled device (CCD) line scan sensor, the scattered light c an be measured not only with high temporal but also with improved spatial r esolution. Thereby, the quantity to be measured by PDA, the phase differenc e Delta phi, can be determined as function of the elevation angle psi. This allows a statistical evaluation of the received signal and permits precise measurements of the size and velocity even of non-ideal solid particles wi th inhomogeneous composition, aspherical shape or rough surface. In this paper, the basis of data acquisition and evaluation is described. T his is followed by experimental results for glass spheres with intact and d efect surfaces and, for comparison, for water droplets. These results demon strate the potential of this measuring device, described as a differential phase-Doppler anemometer (DPDA).