Industrial PhD on Propeller Icing on Unmanned Aerial Vehicles

The radical increase in use- and development of UAVs worldwide has also led to the operation of UAVs under more severe weather conditions, like for example atmospheric icing. Atmospheric icing occurs when an aircraft travels through a cloud with supercooled (temperature below the freezing point) liquid droplets. The goal of this project is to assess the danger of the resulting ice accretion on the propeller of a UAVs and develop a system to prevent the ice accretion on the propeller. Numerical simulation analyses on ice accretion on the propeller will be used to esta blush models that calculate the shape of the ice on the propeller. The generated ice shapes are used to analyse the performance losses of the propeller. In addition to numerical simulations, experiments will be performed in a special icing wind tunnel. These experiments will be used to validate the numerical simulations. Using those methods, the parameters influencing the ice accretion on the propeller will be analysed. These parameters include the different meteorological conditions and the size and speed of the propeller. The first analyses from the current project support preliminary data showing that icing on a propeller has a large influence on the performance of the propeller. This influence is highly dependent on the temperature. The influence of the meteorological conditions is different compared to the ice accretion on the airframe of an UAV. To enable the safe operation of UAVs in icing conditions, an ice protection system for a propeller will be developed. This system will use electric heating elements, to prevent ice accretion on the propeller. The system will prevent the negative effects of icing on the propeller and enable safe operation of UAVs in icing conditions.

Unmanned aerial vehicles (UAVs) is an emerging technology with a large variety of commercial and military applications. In-flight icing occurs during flight in supercooled clouds or freezing precipitation and is a potential hazard to all aircraft. Icing on UAVs imposes a major limitation on the operational envelope. The purpose of this project is to generate knowledge about atmospheric icing on UAV propellers. This work follows research activities conducted at the Norwegian University of Science and Technology (NTNU) and UBIQ Aerospace. The existing knowledge base has focussed on icing of the airframe (wings and airfoils), whereas the current project will focus on propellers and rotors. This research project will address three key research questions: * How does ice accumulate on a UAV propeller? * How does the ice affect the aerodynamics and the thrust generation? * How to design ice protection systems specifically for UAV propellers? To answer these research questions numerical and experimental methods will be used. The overall strategy will be to establish a simulation-chain that is able to simulate the icing physics using commercially available simulation tools and to validate it with experimental results. A computational fluid dynamics (CFD) code for icing simulation called ANSYS FENSAP-ICE will be used for the numerical methods. This tool has been developed for manned aviation purposes but has recently been applied successfully for UAVs as well. The tool is capable of simulating ice accretion, aerodynamic performance degradation, and ice protection systems. The numerical simulations will be accompanied by experimental tests in icing wind tunnels. Such facilities are able to recreate icing conditions under laboratory conditions. The experimental results will be used to validate the numerical simulations.