Method for Designing Hybrid Airfoils for Icing Wind-Tunnel Tests

The certification of modern commercial aircraft requires manufacturers to demonstrate flight safety under various scenarios, including icing conditions. Although computational tools play a key role in icing-related aircraft design and certification, icing wind-tunnel testing remains an important part of the process. The size of models that can be tested is limited by the dimensions of the existing icing wind-tunnel facilities. To obtain ice accretions on full-scale aircraft wings in icing wind tunnels, scaling methods must be applied. One attractive option is the use of hybrid airfoils. Hybrid airfoils present the same leading-edge geometry of the full-scale airfoil but replace the aft section with a redesigned geometry of reduced chord. When properly designed, these models generate the full-scale ice accretion on the leading edge, with reduced blockage and aerodynamic loads. This paper presents an investigation of the effects of different design parameters on the performance of hybrid airfoils, identifies the key design parameters to generate full-scale ice shapes, and puts the research findings in perspective with overall model design tradeoffs.