UAV Icing: 3D Simulations of Propeller Icing Effects and Anti-Icing Heat Loads

In-flight atmospheric icing is a significant threat to the use of unmanned aerial vehicles (UAVs) in adverse weather. The propeller of the UAV is especially sensitive to icing conditions, as it accumulates ice at a faster rate than the wings of the UAVs. Ice protection systems can be developed to counteract the danger of icing on the propeller of UAVs. In this study, the influence of different meteorological conditions on a propeller of a UAV is analyzed for a UAV with a wingspan of a few meters. The ice accretion and the performance degradation and the required anti-icing heat fluxes have been calculated using numerical methods with ANSYS FENSAP-ICE. This analysis has been used to evaluate the critical conditions for the operation of a UAV in icing conditions and the design of a thermal IPS system for a propeller. The highest ice mass has been found at a temperature of −10 °C and an MVD of 20 μm in intermittent maximum icing conditions. The performance degradation has been the highest at lower temperatures of −15 °C in intermittent and at −5 °C in continuous maximum icing conditions. For the design of an IPS, the conditions at the lowest design temperature and the smallest median volumetric diameter (MVD) have been identified as critical points. The most important driver for the required IPS loads on the propeller is the outside temperature, followed by the liquid water content of the cloud. The MVD is important for the distribution of the liquid water content. Here, the highest heat flux required for anti-icing has been computed. The second critical design point is the highest temperature, at an MVD of 40 μm. At this condition, the heat flux is the lowest. This analysis is the basis for the development of electro-thermal IPS for use in UAVs. This paper expands previous research to cover the effect of icing on a propeller of a UAV in a wide range of icing conditions and explains the influence of those conditions on an IPS design.