The Effects of the Substrate Thermal Conductivity on the Dynamic Ice Crystal Icing Process Over Heated Airfoil Surfaces

This study investigates the influence of substrate thermal conductivity (K_S) on dynamic ice crystal accretion over airfoil surfaces under simulated glaciated icing conditions. Experiments were conducted in the Iowa State University Icing Research Tunnel using two geometrically identical NACA0012 airfoils, one with an aluminum skin and the other with a stainless-steel skin, exhibiting contrasting thermal conductivities. A theoretical energy balance model establishes a direct proportionality between substrate thermal conductivity and melting rate. A series of tests were performed by varying surface temperature (T_S), free-stream velocity (V_∞), and ambient temperature (T_∞), capturing ice impingement, deposition, melting, shedding dynamics, and transient surface temperature variations using synchronized high-speed imaging and surface-mounted thermocouples. The experimental findings agree with the theoretical model. The results indicate that the thermal conductivity of the airfoil surface significantly impacts ice accretion behavior. The results show a higher rate of ice build-up and greater overall ice mass accumulation at the leading edge of the aluminum surface (K_Al = 170 W/m*K) compared to the stainless-steel surface (K_SS = 16.3 W/m*K) under similar test conditions. This difference is due to the aluminum surface reaching a lower equilibrium temperature (T_eq) than stainless steel, promoting a favorable melt ratio and stronger ice adhesion, which enhances ice growth and reduces shedding. Notably, ice shedding occurs earlier as the surface temperature increases from 0 °C to 10 °C, particularly on the aluminum surface, where complete shedding is observed. In contrast, the stainless-steel surface exhibits partial and localized shedding that appears randomly. The outcomes underscore the critical role of material properties in mitigating ice crystal icing hazards in aero-engine components.