A hybrid anti-icing ice protection system

A hybrid ice protection system has been developed to provide an economical alternative to conventional anti-icing systems on roughness sensitive airfoils where high power is either impractical or unavailable. It consists of a thermal subsystem operating in a running-wet mode that partially or fully covers the impingement zone at the leading edge, and a low power de-icing subsystem just downstream. The thermal system maintains a clean leading edge in the roughness sensitive zone by preventing the impinging supercooled water droplets from freezing. This requires minimal power because the surface temperature is held just above freezing. The heated water then runs back and freezes downstream where the low power de-icing system removes the ice contamination periodically. The total power consumption of the hybrid system is a fraction of that required to achieve total evaporation. Tests conducted in the NASA Lewis Icing Research Tunnel on a truncated horizontal stabilizer section of a light business jet proved the hybrid system to be a viable alternative to conventional anti-icing systems that require substantial power.