Convective heat transfer from realistic ice roughness distributions.

As supercooled water droplets impinge the surfaces of in-flight aircraft, a layer of accreted ice will form. In the initial stages of the accretion process, the ice will form as a distributed surface roughness. Ice accretions degrade the aerodynamic performance and safety of an aircraft. Icing effects are simulated and mitigated during aircraft design through the use of computational ice accretion codes. A significant area for improvement of these codes exists in the simplistic characterization of convective heat transfer from ice roughness. A better characterization of convective heat transfer must be obtained for flows over surfaces with realistic ice roughness properties and relevant thermal boundary conditions. A series of steady state experiments was performed in a wind tunnel on a flat plate with two realistic ice roughness surfaces. Using an infrared camera, detailed maps of convective heat transfer coefficients were obtained for the surfaces.