Signal Processor for Doppler Measurements in Icing Research

An advanced signal processor has been developed to enable high-resolution measurement of the frequency and phase shifts of noisy laser Doppler velocimeter (LDV) and phase Doppler particle analyzer (PDPA) signals. The purpose of the measurements is to exploit the phase Doppler principle to determine the sizes and velocities of droplets entrained in airflows. By enabling such measurements, this signal processor is making it possible to perform ground-breaking research in icing of airplanes and combustion of liquid fuels, involving (1) water-droplet-laden, high-speed airflows that simulate clouds flowing past airplanes and (2) high-speed, dense sprays of liquid fuels, respectively.