Aerodynamic Effect of Artificial Ice Shapes on the 5.2% Scale Semispan High-Lift Common Research Model in the NASA National Transonic Facility

The in-flight icing of aircraft is an important safety consideration that can impact configuration and sizing during preliminary design stages. Experimental data are needed to help improve and validate computational simulation tools. These tools are needed to develop and optimize advanced aircraft designs for fuel efficiency and reduced noise. The High-Lift Common Research Model (CRM-HL) effort is addressing this need to generate high-quality iced aerodynamic data at flight Reynolds number on a modern commercial transport airplane. This paper describes an experimental effort to quantify the aerodynamic degradation due to artificial ice shapes attached to a 5.2% scale semispan model of the CRM-HL in the NASA National Transonic Test Facility (NTF). Computer simulations were performed using FUN3D for airflow and LEWICE3D for ice-shape predictions. Realistic icing scenarios were analyzed to define an ice-shape configuration for aerodynamic testing. Artificial ice shape parts were fabricated with 3D printing and the ice parts were adhered to the model for aerodynamic testing. Clean and iced model testing was performed at Reynolds number based upon mean aerodynamic chord of 5.3 to 30.0×10^6 at Mach number equal to 0.2 for the CRM-HL landing configuration. The reduction in maximum lift coefficient ranged from 8.0% to 9.8% depending upon Reynolds number and ice-shape configuration. The corresponding range of stall angle reductions was 1.0 to 3.4 deg. Data collected for the iced model at Re_c = 16.0 and 30.0×106 represent the first public domain documentation of iced-airplane performance effects at flight Reynolds number known to the authors and is thus an important contribution toward better understanding an important flight safety aspect. Future test campaigns should consider additional artificial ice configurations to better understand the sensitivity to spanwise location and variations in Mach number that represent realistic approach and landing speeds.