The experimental investigation of a rotor hover icing model with shedding

Icing environments have long been an issue for rotorcraft. Flight in icing conditions is fraught with operational hazards, including reduced vehicle performance and large torque rises. Shedding of ice from blades due to centrifugal forces poses a ballistics danger to the aircraft and creates large vibrations due to imbalanced rotors. Modeling the effects of accreted ice on rotorcraft flight performance has been a challenge due to the complexities of periodically changing conditions as well as spanwise variations of angle of attack, velocities and surface temperatures. A new icing model has been developed to model the ice accretions across a rotor in hover. A shedding module is used to predict the shedding events and station. This model was correlated with published ice shapes for both small and full scale ice accretion results. The shedding module was evaluated based upon experimental results in the newly developed Adverse Environment Rotor Test Stand (AERTS). Favorable comparisons have been made between ice thickness, impingement limits and ice shape, especially at inboard stations. Shedding behavior was also evaluated, but required correction factors to improve test data correlation. Further investigations are required, but the icing model has demonstrated the ability to predict rotor icing trends.