Three-Dimensional Ice-Accretion Measurement Methodology for Experimental Aerodynamic Simulation

Determining the adverse aerodynamic effects due to ice accretion often relies on dry-air wind-tunnel testing of artificial, or simulated, ice shapes. Recent developments in ice-accretion documentation methods have yielded a laser-scanning capability that can measure highly three-dimensional features of ice accreted in icing wind tunnels. The objective of the current study was to evaluate the aerodynamic accuracy of ice-accretion simulations generated from laser-scan data. Tests were conducted in the NASA Glenn Icing Research Tunnel, where ice accretions were measured with laser scanning before the molding process. Aerodynamic performance testing was conducted at the University of Illinois low-speed wind tunnel at a Reynolds number of 1.8 x 10(6) and a Mach number of 0.18 with an airfoil model designed to accommodate artificial ice shapes. The ice-accretion molds were used to fabricate one set of artificial ice shapes from polyurethane castings. The laser-scan data were used to fabricate another set of artificial ice shapes using rapid-prototype manufacturing. The iced-airfoil results with both sets of artificial ice shapes were compared to evaluate the aerodynamic simulation accuracy. The data showed that the laser-scan and rapid-prototype manufacturing approach was capable of replicating small ice features within the reported accuracies of the laser-scan measurement and rapid-prototyping methods, thus providing a new capability for high-fidelity ice-accretion documentation and artificial ice-shape fabrication for icing research.