Novel Image Measurement Method of Diameter Distribution of Dynamic Supercooled Water Droplet

A novel dynamic supercooled droplet diameter measuring method based on optical image processing is presented in this paper. The diameter distribution of dynamic supercooled water droplets (SWDs) of a novel self-built icing wind tunnel equipment is detected under low temperature circumstances. The diameter and diameter distribution of dynamic SWDs are important factors affecting the growth rate of aircraft wing icing. And they are key parameters for icing wind tunnel equipment in this paper. The images of dynamic SWDs are captured by a high-speed industrial camera. And the image size calibration is implemented by comparing the physical size with its pixel size. The measurement error of the novel measuring method is determined by measuring the pixel size of a molybdenum wire and the results show that the error is within 5%, and it met J. T. Kashdan’s suggestion about the measurement error of 100μm particle size. The measuring experiment was carried out under low temperature circumstances in Jilin City, Jilin province, China. The final measurement results show that the diameter of dynamic SWDs ranges from 25.63μm to 110.21μm and volume fraction distribution fits the normal distribution basically. The median volume diameter of dynamic SWDs is 68.95μm, and range from 65.6μm to 76.4μm when the fan power and the water pressure are changed from 50W to 400W and 40kpa to 90kpa respectively, quite stable.