HAP 1: Aerodynamic Analysis

Ice accretion on wings of aircrafts decreases significantly the aerodynamic performance. On the one hand, the aerodynamic drag is increased that has to be compensated with additional thrust of the engines. Consequently, this yields increased fuel consumption. On the other hand, the flow stalls at lower angles of attack. Therefore, the operational range of safe aircraft manoeuvring is reduced.

To better understand the ice accretion process as a consequence of the accumulation of super-cooled, large droplets, theoretical, numerical and experimental methods of aerothermodynamics shall be applied. The research is focussed on three main areas:

1. What is the influence of droplet dynamics of super-cooled large droplets on the ice accretion process? If a large droplet impinges on a surface, small secondary droplets are created that are shed back to the flow. Only a part of the original droplet mass remains on the aircraft wing.
2. Besides the geometric ice shape on the wing, is there an influence of any material property or macroscopic structural parameter of ice, which alters the surrounding flow?
3. In which way has the numerical simulation of the ice accretion process to be carried out? The current numerical models of ice growth are based on a thermodynamic balance equation. However, the different terms in this equation are model dependent and shall be analyzed regarding their impact on ice accretion. Particularly, the friction heat and the convective heat transfer are expected to have a big impact.

Many of the experiments will be carried out at the new icing tunnel of Technische Universität Braunschweig (completion in spring 2013), which is unique across Germany. In this tunnel, ice accretion and ice growth can be studied using a generic airfoil. The experimental results will then be compared with the computational predictions

Paticipating Institutes:

• Institut für Aerodynamik und Strömungstechnik (DLR)
• Institut für Strömungsmechanik (TUBS)