Rotorcraft vehicles are highly sensitive to ice accretion. When ice forms on helicopter rotor blades, performance degradation ensues due to a loss of lift and rise in drag. The presence of ice increases torque, power required, and leads to rotor vibrations. Due to these undesirable changes in the vehicle's performance, the FAA requires intensive certification to determine the helicopter’s airworthiness in icing conditions. Since flight tests and icing tunnel tests are very expensive and cannot simulate all conditions required for certification, it is becoming necessary to use computational solvers to model ice growth and subsequent performance degradation. Currently, most solvers use the strip theory approach for 3D shapes. However, rotor blades can experience significant span-wise flow from separation or centrifugal forces. The goal of this work is to investigate the influence of span-wise flow on ice accretion. The classical strip theory approach is compared to a curved surface streamline based approach to assess the relative differences in ice formation.

An improved knowledge regarding what spatial scale temperature data is needed for ice-prediction would improve calculations how ice-coverage has been affected over time. Which by extension would give insight how ice might response to climate change. The purpose of this study was to find out if ice-growth in Sävar River could be explained by both local and regional temperature data, and what factors beyond temperature affect ice-growth. To accomplish this, I analyzed time-lapse photos from Sävar River during a three-month period. I found out that the use of regional temperature data to explain ice-growth on a local scale is limited due to the differences in accumulated degrees. The local temperature data measurement accumulated -2281 °C from ice began to grow until the whole channel was ice-covered and the regional temperature data accumulated -1901 °C under the same period. My findings support the assumption that frazil ice in large concentrations seem to increase ice-growth. Furthermore, no relation between ice-growth/decrease and precipitation or wet spots was found in this study.