Preliminary research on size measurement of supercooled large droplet in icing wind tunnel

Drop-size measurement of the supercooled large droplet (SLD) is very important for capacity building of the icing wind tunnel. In order to evaluate the capability of Phase Doppler Interferometer Flight Probe Dual Range (PDI-FPDR) in measuring the diameter of SLD, the standard droplet stream generated by a droplet generator, was used to evaluate the uncertainty of PDI-FPDR for drop size measurement. Then, for the real large-droplet spray, the particle size characteristic parameters were measured by Malvern and PDI-FPDR simultaneously. The large-droplet spray measurement capability of PDI-FPDR has been further evaluated. The results show that the small size range channel of PDI-FPDR can't accurately measure large droplets, and its measurement results are much smaller than the real droplet size. The relative error of measuring a 189.0 μm droplet is -72.8%. The measuring accuracy of the large size range channel is high, but the precision is poor. The relative error of measuring a 240.5 μm droplet is -5.1%, and the maximum deviation is 50.2 μm. For typical large-droplet spray, the PDI-FPDR small size range channel has poor applicability under measuring conditions of median volume diameter (MVD) greater than 75.0 μm. The measured MVD values of PDI-FPDR large size range channel are larger than those of Malvern.