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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.

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.

The simulation of icing conditions in icing wind tunnels (IWTs) is a significant element in the certification of aircraft components and offers unique possibilities for research purposes. Up to 2014 only the conditions defined in Appendix C of the EASA Certification Specification 25, respectively the FAA Code of Federal Regulations Title 14 Part 25 were used for the certification processes in IWTs. In addition, Appendix O was introduced in 2014 to cover the supercooled large droplet (SLD) icing conditions of freezing drizzle and freezing rain, which pose a potential risk for flight safety. The simulation of SLD icing in IWTs is, due to the different behavior of the large droplets, very challenging and not all required conditions have successfully been recreated yet. RTA Rail Tec Arsenal Fahrzeugversuchsanlage GmbH has focused on the simulation of in-flight icing conditions since 2012 and increased effort was put in the simulation of SLDs in recent years.