Ultrasonic De-Icing Bondline Design and Rotor Ice Testing

The use of ultrasonic excitation has shown the ability to promote ice shedding of impact ice (less than 2 mm thick) during prior wind-tunnel testing efforts. The ultrasonic de-icing technology is implemented to structures representative of rotorcraft blade leading edges and tested under impact icing and centrifugal environments (390 g). Finite element models are experimentally validated and used to predict the ultrasonic ice shedding transverse shear stresses responsible for ice shedding. The finite element models tools are then used to guide the design of a robust bondline between the lead zirconate titanate actuators and the host structure. The novel bondline approach is implemented to a rotor blade leading-edge erosion cap representative structure (0.813-mm-thick stainless-steel leading edge). The system is tested under centrifugal loads and icing conditions generic to helicopter operational envelopes. Details on the de-icing system fabrication and integration are provided. The bondline configuration does not degrade during operation and increases the ice interface transverse shear stresses by 15% with respect to prior bonding approaches. To promote ice shedding of impact ice, a system control to identify and excite optimum de-icing modes during rotor ice testing is also implemented and described in this paper. The power consumption of the de-icing system is quantified to average 0.63 W/cm(2). The de-icing system is able to promote shedding of ice layers ranging from 1.4 to 7.1 mm in thickness for varying icing conditions representative of helicopter icing environments.