Rotor Icing and De-Icing Tests in the DLR Rotor Tower

Kurzfassung

The paper presents experimental rotor icing investigations in the DLR rotor icing test facility EVA (Eis-VersuchsAnlage) within the frame of the DLR project SAFER2. The project mainly addressed the challenges arising from the combination of sensor technology, machine learning methods, and artificial intelligence in the control of complex technical systems, with regard to functionality and operational safety. In this project, the rotor test stand inside EVA was one of five selected demonstrator platforms for gathering data for ML (Machine Learning) algorithms. In this case, the measurement data comes from sensors integrated or attached to the rotor blades, as well as from a novel optical sensor in the non-rotating frame. The blade-mounted units include piezo sensors using guided waves for structural health monitoring (SHM) and the DLR technology for local icing layer detection (LILD). Additionally, the DLR concept sensor for optical detection of icing conditions (ODIC) measures liquid water droplets, ice particles, and the liquid water content of the ambient air. For testing purposes, the rotor system was equipped with new blades featuring electrical heater systems at the blade tips for de-icing and anti-icing. These tests aim to investigate energy-efficient blade de-icing methods. This technology is essential for small and medium-sized helicopters, which currently lack dedicated rotor de-icing systems. The paper gives an overview of the sensor systems as well as the test campaign. Selected results from de-icing and anti-icing measurements, including temperature and load measurements from the rotating system, as well as results and findings from the guided surface wave sensors used for ice detection and measurement are presented. The measurement results from the ODIC sensor are highly relevant for assessing the quality of the icing conditions. The results presented show that the icing conditions set correspond to those specified in EASA CS-29, Appendix C.