Performance of the Phase Doppler Particle Analyzer icing cloud droplet sizing probe in the NASA Lewis Icing Research Tunnel

The design, development, and testing of an icing cloud droplet sizing probe based upon the Phase Doppler Particle Analyzer (PDPA) are discussed. This probe is an in-situ laser interferometry based single particle measuring device capable of determining size distributions. The probe is designed for use in harsh environments such as icing tunnels and natural icing clouds. From the measured size distribution, Median Volume Diameter (MVD) and Liquid Water Content (LWC) may be determined. Both the theory of measurement and the mechanical aspects of the probe design and development are discussed. The MVD results from the probe are compared to an existing calibration based upon different instruments in a series of tests in the NASA Lewis Icing Research Tunnel. Agreement between the PDPA probe and the existing calibration is close for MVDs between 15 to 30 microns, but the PDPA results are considerably smaller for MVDs under 15 microns.