UAV Icing: Experimental Characterization of the Performance Impact of Ice Accretion on a Propeller

Ice accretion is a significant threat to the operation of UAV in cold climates. This study analyzed the performance degradation caused by ice accretion on a propeller with a diameter of 0.53 m for a small UAV in an icing wind tunnel. Three different droplet diameters of 20, 40, and 60 µm were tested along with three liquid water contents between 0.28 g/m3 and 1.12 g/m3 along with temperatures of —5 °C, —10 °C, and —15 °C. Additionally, the influence of the variation in the rotation rate was measured. The droplet diameter was observed to have the strongest influence on the propeller’s performance. An increase in the median volume diameter from 20 µm to 40 µm was correlated with a significant decrease in the propeller’s performance. After a minute of icing, the experiment at 20 µm showed a reduction in thrust of 25% compared to a decrease in thrust by 100% for the 40 µm case and 120% for the 60 µm case, meaning that the propeller is not generating thrust, but is generating drag. The temperature influences the propeller’s performance, with the most substantial performance degradation at —5 °C and a decrease in the performance impact with a temperature reduction. Analyzing the performance impact is an important step for deploying UAVs in icing conditions by detecting the most critical conditions for the performance of a UAV propeller. The analysis shows that the most critical conditions are at —5 °C and that an increase in droplet diameter and liquid water content leads to more severe icing conditions. The results show the need for future analysis comparing the performance impact of a propeller at different icing wind tunnels and the validation of numerical methods for predicting the performance degradation of a UAV propeller.