Rotor Blade Shed Ice Length Prediction

Shed ice from rotor blades is a potential ballistic concern for rotorcraft. Ice projectiles could damage the tail rotor or fuselage, and shed ice could also be ingested by the engine. Substantial research has already been conducted in the areas of ice adhesion strength, shedding, projectile trajectories, and impact damage. Work on predicting the shed ice size as it slides off a rotating blade will be discussed in this paper. An Euler-Bernoulli beam model was developed to predict the ice length of shed ice as it is removed from the rotor under the effect of centrifugal forces. The model was validated with experiments conducted at the Adverse Environment Rotor Test Stand at the Pennsylvania State University. The ultimate tensile strength of the ice was experimentally measured, given the scattered ice tensile strength data found in the literature. It was found that the ultimate tensile strength on impact ice at the tested condition was 0.597 MPa with a standard deviation of 28%. High-speed cameras captured the ice break up for size quantification. The model was able to predict the ice length of fragmented shed ice within 22%.