Icing Wind Tunnel Test Campaign on a Nacelle Lip-Skin to Assess the Effect of a Superhydrophobic Coating on Ice Accretion

Abstract

The formation of ice on nacelle causes the reduction or loss of aerodynamic performance, fuel consumption increases, reduced thrust, and the ingestion of ice, which can damage the engine. The piccolo tube anti-icing employed as an active ice protection system has limitations in terms of performance losses and energy costs. Furthermore, according to the FAA regulation, it cannot be activated during takeoff and initial flight phases in order to avoid engine thrust reduction. This work reports on an icing wind tunnel test campaign performed at initial flight phases conditions on the M28 PZL nacelle before and after the application of a superhydrophobic coating in order to study the effect of wettability on ice accretion. Results highlighted that an ice thickness reduction of −49% has been recorded at −12 °C, matched to an increase in the impingement length of 0.5%. At 95 m/s and at 420 s of exposure time, the ice thickness was reduced by −27% and −14%, respectively, whereas the impingement length reductions were −9.6% and −7.6%. Finally, an ice thickness reduction of −8% was observed at a liquid water content of 1 g/m3, matched to an increase in the impingement length of 3.7% and to a reduction in length and number of the frozen rivulets.