The research program VI (LuFo VI-2) of the German Federal Ministry of Economics and Climate Protection (BMWK), called NANNY (INnovative ANd AuftriebssYsteme für die nächste Generation leichter bis mittelschwerer Hubschrauber), aims to develop the predictive capability of the approach and lift systems of light to medium-weight helicopters. Within the project, the Institute of Fluid Mechanics of the TU Braunschweig, together with the Department of Fluid Mechanics and Aerodynamics of the TU Darmstadt and Airbus Helicopters, deals with the icing of the main rotor of a helicopter configuration with the aim of advancing the concept of "digital twins" in the design process of rotorcraft with respect to icing resilience.
The TU Braunschweig uses numerical simulation methods for this purpose with the aim of investigating the physical models that represent the ice accretion on the rotor blade as a whole. For the numerical simulation of the ice accretion on a helicopter rotor blade, various aspects of the multiphase flow must be correctly represented. In addition to the aerodynamic simulation, this also includes the mass and energy balance of the ice formation for each individual rotor blade section. This requires the simulation of the collection efficiency of the supercooled water droplets, the correct modeling of the adhering water mass, the simulation of the movement of the liquid phase on the rotor blade and the determination of the heat transfers. The already existing simulation tools of the Institute of Fluid Mechanics will be extended based on experimental results for the special application on rotor blades. For this purpose, basic experiments will be carried out at the TU Darmstadt, which will capture in detail the ice accretion caused by small, supercooled droplets with high impact velocities.
At the end of the project, the developed numerical methods of the TU Braunschweig will allow the simulation of the icing of a rotating three-dimensional rotor blade. In order to investigate the influences of the individual physical effects on the results of the icing simulation, a sensitivity analysis will be performed. Furthermore, a comparison with a numerical and experimental data set from Airbus Helicopters is performed to validate the methods. The results of the sensitivity analysis and the validation can then be used by Airbus Helicopters to optimize the deicing system and thus contribute to efficient aviation.