Search Results

This paper introduces a recent development in electrothermal heating technology that enables increased power densities on the leading edge of aircraft wings for the purpose of de-icing. Key aspects of this development include a high temperature heater mat, minimal thermal interference between the heating element and leading edge skin, a high quality bond of the heater to the skin and a power density profile that compensates for non-uniform thermal loads on the leading edge skin. Icing tunnel testing results corroborate the value of these key aspects in enabling operation at extreme power densities, even to the point of achieving full evaporative anti-icing operation under Intermittent Maximum conditions. The advent of higher power density capabilities has opened the door to new approaches to electrothermal deicing that were previously impracticable. Some of these new approaches and their benefits are presented.

If an Unmanned Aerial Systems (UAS) encounters icing conditions during flight, those conditions might result in degraded aerodynamic performance of the overall UAS. If the UAS is not reacting appropriately, safety critical situations can quickly arise. Thereby, the rotors, respectively the propellers of the UAS are especially susceptible due to the increased airflow through their domain and the corresponding higher impingement rate of supercooled water droplets. In many cases, the UAS cannot be properly operated if the rotors are not fully functional, as they are a vital component. The FFG/BMK funded research and development project “All-weather Drone” is investigating the icing phenomenon on UAS rotors for a 25 kg maximum take-off weight (MTOW) multirotor UAS and evaluating the feasibility of possible technical ice detection and anti-/de-icing solutions.

Under the EU Clean Sky 2 research project InSPIRe – Innovative Systems to Prevent Ice on Regional Aircraft, numerical and experimental studies have been performed to investigate the potential to minimise the electrical power required for wing ice protection on a regional aircraft wing. In a standard electrothermal de-ice protection scheme there is a parting strip heater which runs along the full spanwise protected extent and is permanently powered. This splits the ice formation on the leading edge into an upper and lower region, which makes it easier to shed. However, the parting strip is relatively energy intensive and contributes a significant portion of the overall power demand. Developing a system which is able to provide the desired ice protection function without a parting strip would therefore offer a substantial power saving. The great difficulty with such a system is in ensuring that acceptable ice shedding occurs.

Research institutes and companies are currently working on 3D numerical icing tools for the prediction of ice shapes on an international level. Due to the highly complex flow situation, the prediction of ice shapes on three-dimensional surfaces represents a challenge. An essential component for the development and subsequent validation of 3D ice accretion codes are detailed experimental data from ice shapes accreted on relevant geometries, like wings of a passenger aircraft for example. As part of the Republic of Austria funded research project JOICE, a mockup of a wingtip, based on the National Aeronautics and Space Administration common research model CRM65 was designed and manufactured. For further detailed investigation of electro-thermal de-icing systems, various heaters and thermocouples were included.

Aircraft icing is a significant issue for aviation safety. In this paper, recent developments for calculating the trajectory of non-spherical particles are used to determine the trajectory and impingement of ice crystals in aircraft icing scenarios. Two models are used, each formulated from direct numerical simulations, to give the drag, lift and torque correlations for various shaped particles. Previously, within the range of Reynolds number permitted in this study, it was only possible to model the trajectory and full rotational progression of cylindrical particles. The work presented in this paper allows for analysis of a wider range of ice shapes that are commonly seen in icing conditions, capturing the dynamics and behaviours specific to ice crystals. Previous limitations relate to the in ability to account for particle rotation and the dependency of force correlations on the measure of particle sphericity - which are now overcome.

This paper details the process involved in the numerical optimisation of a helicopter engine inlet electrothermal ice protection system. Although the process was developed using a production aircraft, it is demonstrated here using a generic intake and flight conditions, due to confidentiality of the actual design. The process includes adherence to the overall system design objectives (maximum power demand), including tolerances required to account for an industrial system (aircraft voltage variation, manufacturing tolerances). The numerical optimisation was performed using a combination of 2D and 3D methods to define the required heated area, power density, locations and settings for temperature control sensors. The use of 2D design tools allows a rapid iteration process to be performed, leading to the possibility of a higher level of optimisation within the allowable time-frame compared to the use of full 3D methods.