Search Results

3D-scanning is an established method for the documentation of wing ice accretion. The generated 3D-data can be used to determine specific parameters of interest, like the local ice-thickness, or the surface ice roughness. The surface roughness has significant impact on the heat transfer, and therefore on the icing process itself. Insights into the effects of surface roughness on the ice accretion and the correlated aerodynamical effects contribute to the improvement of icing codes. In this paper, the surface roughness of various test specimens is determined by performing a self-organizing maps (SOM) approach for roughness point cloud analysis on data generated with a 3D-scanner. A validation of the SOM method is achieved by means of focus variation microscopy and a mathematical proof of the utilized SOM algorithm. Different scanning systems from several manufacturers are used to determine the surface of different sandpapers.

In the scope of development or certification processes for the flight under known icing conditions, aircraft have to be tested in icing wind tunnels under relevant conditions. The documentation of these tests has to be performed at a high level of detail. The generated data is used to prove the functionality of the systems, to develop new systems and for scientific purposes, for example the development or validation of numerical tools for ice accretion simulation. One way of documenting the resulting ice geometry is the application of an optical 3D scanning or reconstruction method. This work investigates and reviews optical methods for three-dimensional reconstructions of objects and the application of these methods in ice accretion documentation with respect to their potential of time resolved measurement. Laboratory tests are performed for time-of flight reconstruction of ice geometries and the application of optical photogrammetry with and without multi-light approach.

The demand for low power ice protection systems and the introduction of further regulations for flight into known icing will stretch current technologies and the analytical tools required to support them. This paper considers an approach in the development of an analysis tool for the assessment of a combined electro-thermal and electro-mechanical deicing system. The tool development is part of a 4 year EU programme (project ‘HETEMS’ - Hybrid ElectroThermal and ElectoMechanical Simulation) and will include the icing wind tunnel testing of a hybrid deicing system to provide validation data. The various analytical components required by the system are presented and some of the issues in applying them are discussed. The tool will aim to provide both a 2D and 3D capability and allow both conceptual and detailed design strategies.

When conducting experiments in icing wind tunnels (IWTs), a significant question is to what extent the temperature of the water droplets generated by the spray system has converged to the static air temperature when the droplets impinge on the test object. This is a particularly important issue for large droplets, since the cooling rate of droplets decreases sharply with increasing diameter. In this paper, on the one hand, realistic droplet temperature distributions in the measurement section of the Rail Tec Arsenal IWT (located in Vienna) are computed by means of a numerical code which tracks the paths of the droplets from the spraying nozzle to the measurement section and simultaneously calculates their cooling rates. On the other hand, numerical icing simulations are performed to investigate to what extent the deviation of the droplet temperature from static air temperature influences icing and thermal anti-icing processes.

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.

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.

In the course of the Horizon 2020 project ICE GENESIS of the European Union, an experimental database was developed to host documentation of icing experiments. The database serves as a source of information for numerical code development and validation as well as future test matrix design, IPS layout and development and wing design. Several legacy data icing cases have been included into the database, which are partly publicly available. Furthermore, the database will serve as the main platform for dissemination of public results of icing cases after and during the project ICE GENESIS. The database itself provides detailed information about the test configurations and the icing wind tunnel. More specifically, CAD data, ice protection system characteristics if applicable, installation in the test facility, instrumentation, test matrix, generated aero-icing conditions and test results are included.

Low power ice protection systems are an important research area that is highlighted in the EU Clean Sky programme. In this paper an icing wind tunnel test of a full-scale wing incorporating both an electro-thermal and a hybrid electro-thermal electro-mechanical system is described. A description of a software tool to analyse both systems as full 3D models is also given. Preliminary comparisons of test data and prediction are shown both for the electro-thermal system and the hybrid system. Initial comparisons show a reasonable correlation in the main with recommendations for a structure tear-down to identify exact internal transducer locations. Recommendations are also made with regard to undertaking tests to determine a more consistent set of mechanical failure properties of ice. Future work in the development of the tool is also discussed.

Accurate calculation of the catch efficiency β is of paramount importance for any ice accretion calculation since β is the most important factor in determining the mass of ice accretion. A new scheme has been proposed recently in [1] for accurately calculating β on a discretized two-dimensional geometry based on the results of a Lagrangian droplet trajectory integrator (start and impact conditions). This paper proposes an extension to the algorithm in Ref. [1], which is applicable to three-dimensional surfaces with arbitrary surface discretization. The 3D algorithm maintains the positive attributes of the original 2D algorithm, namely mass conservation of the impinging water, capability to deal with overlapping impingement regions and with crossing trajectories, computational efficiency of the algorithm, and low number of trajectories required to reach good accuracy in catch efficiency.

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.

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.

Results are presented from the application of the ICECREMO code to various geometries. ICECREMO is a 3D ice accretion model, based on a structured approach. It does not include a CFD solver and therefore may be used in combination with a range of CFD packages. The code consists of a Lagrangian particle tracking module, a splash and bounce module, a water film thickness and motion module, a heat transfer module, and a freezing module. This paper aims to show the ability of the ICECREMO code to accurately predict droplet catch and ice accretion on components where the flow is highly 3D. The use of 2D icing analysis is widespread and has been shown, in certain cases, to prove reliable. However, in situations where the flow is highly 3D, such as with instances of geometrical double curvature, a 3D icing analysis is not only desirable, but necessary.

Current modelling capability for engine icing accretion prediction is still limited for App. C. To further validate icing codes in complex engine geometries, it is necessary to perform additional experimental work in relevant geometrical and environmental conditions. Within the frame of ICE GENESIS [1], an experiment has been setup to replicate the condition at the inlet of an engine first stage compressor. This paper describes the choices for the design of the engine compressor model, the setup within the icing wind tunnel and the methodology employed to obtain the results. Additionally, more effort has been focused on obtaining accurate ice shapes using a 3D scanning system. Results of 3D scans are given.

The European Union’s Horizon 2020 programme has funded the SENS4ICE (Sensors for Certifiable Hybrid Architectures for Safer Aviation in Icing Environment) international collaboration flagship programme. Under this programme a number of different organizations have developed ice detection technologies, specifically aimed at providing information to differentiate between ‘classical’ Appendix C icing conditions and the larger droplets found in Appendix O icing. As a partner within the SENS4ICE project, AeroTex UK has developed an ice detection concept called the Atmospheric Icing Patch (AIP). The sensor utilizes a network of iso-thermal sensors to detect icing and differentiate between small and large droplet icing conditions. This paper discusses the development of the sensor technology with a focus on the outcomes of the flight testing performed on the Embraer Phenom 300 platform during early 2023.

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.

This paper provides information on the comparison of numerical simulations with experimental data for an electrothermal ice protection system with a focus on Appendix O [1] Freezing Drizzle (FZDZ) and Freezing Rain (FZRA) conditions. The experimental data is based on a test campaign with a 2D NACA23012 wing section in the RTA Icing Wind Tunnel in Vienna. 22 icing runs (all either unheated or in anti-ice mode) were performed in total and all residual ice shapes were documented by means of high-resolution 3D scanning. Unheated FZDZ and FZRA reference as well as heated cases with different heater configurations are presented. The experimental results are compared to numerical predictions from two different icing codes from AeroTex GmbH (ATX) and the University of Applied Sciences FH JOANNEUM (FHJ) in Graz. The current capabilities of the codes were assessed in detail and regions for improvement were identified.

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.

The European Union (EU) ‘Clean Sky’ [1] Joint Technology Initiative (JTI) is a research programme aimed at developing breakthrough technologies which will minimise the impact of aviation on the environment. Within this, the System for Green Operations (SGO) Integrated Technology Demonstrator (ITD) looks to improve aircraft operation through management of energy and mission trajectory. As part of the SGO ITD, a series of environmental icing tests have been conducted on an ice protected, acoustically protected, electrically powered, scoop intake and channel. The range of conditions tested included in-flight icing (CS-25 Appendix C, same as 14 CFR 25), super-cooled large droplets (proposed 14 CFR 25 Appendix O, [2]), snow and ice crystal conditions as well as ground icing in freezing fog conditions.

This work introduces an approach allowing the detailed replication of ice shapes generated in icing wind tunnels, with a special focus on complex and strongly varying ice structures, e.g., ice feathers or residual ice stemming from incomplete removal of accreted ice by ice protection systems. 3D-scans are used as an input for the manufacturing process of the ice shape replica. The manufacturing approach itself is based on additive techniques using semi-flexible materials. In contrast to existing replication techniques, this approach allows also clean areas between ice-covered surface locations. In the present paper, a quality assessment based on the comparison of the lift coefficients of real and corresponding artificial ice shapes is presented.