Multi-Location Microwave Ice Sensor for Integrated, Zone-Based De-icing

Atmospheric icing during flight poses a significant risk to smaller autonomous aerial vehicles, drones, and electric vertical take-off and landing crafts. In-flight icing negatively affects their aerodynamics and increases weight, thus restricting their operational envelopes and reducing seasonal reliability. Here a smart ice detection and removal system utilizing multifrequency microwave split-ring-resonator sensors for location-specific impact ice sensing is introduced. The sensor is integrated onto an airfoil with a multizone electrothermal deicing system and a deicing coating for a zone-based ice protection system. Experimental testing is conducted within a refrigerated icing wind tunnel under low-Reynolds number conditions (Re ∼ 10⁵) at airspeeds (20 and 40 m/s) relevant to urban air mobility. The sensor's response to distinct accretion characteristics at −5 °C, −10 °C, and −20 °C and at varying liquid water contents (0.3, 0.5, and 0.8 g/m³) is investigated. The sensor exhibits a high sensitivity of 179 MHz/mm and data postprocessing enables precise monitoring of icing rates under various conditions and with different types of ice accretions for prediction of ice thickness. This proof-of-concept system shows significant potential for use in green energy and aviation sectors, offering prompt and efficient ice protection to maintain the safety and effectiveness of aerospace vehicles.