Convection from realistic ice roughness on a simulated NACA 0012 airfoil.

Ice roughness properties are critically important to the development of ice accretions on aircraft surfaces. Ice accretions degrade aircraft performance by increasing the skin friction drag, increasing the weight of the aircraft, and decreasing the lift and stall angle. During the aircraft design process, icing effects are simulated using ice predictions codes such as LEWICE. These codes can be improved by providing a better characterization of the convective enhancement caused by ice roughness. Previous studies have considered convective enhancement from ice roughness surfaces with constant properties in the flow direction and in a flow with negligible acceleration. This work investigates convective enhancement from realistic ice roughness surfaces by 1) including roughness variations in the streamwise direction as measured in the Icing Research Tunnel at NASA Glenn with laser scanning and 2) including a flow acceleration profile in the flow direction by installing a foam insert on the wind tunnel ceiling.