UAV Icing: Comparison of LEWICE and FENSAP-ICE for Ice Accretion and Performance Degradation

One of the main limitations of the operational envelope of UAVs today is the risk of atmospheric icing. UAV icing is not well researched and this paper aims to generate a better understanding of how ice accretion and aerodynamic performance degradation on UAV airfoils can be simulated. In particular, the objective is to investigate how well a panel-method based code compares to a modern CFD icing code. LEWICE and FENSAP-ICE are used to generate three characteristic 2D ice shapes (rime, glaze, mixed) on a NREL S826 airfoil for low Reynolds numbers. RANS calculations are performed to assess the resulting aerodynamic performance degradation. Validation of the ice growth predictions is achieved by using literature data. Aerodynamic performance degradation is validated with experimental results from a (non-icing) wind tunnel at NTNU. The numerical results indicate that icing morphology has a major influence on the ability of both codes to capture ice shape and aerodynamic penalties. Rime is simulated consistently, whereas predictions for mixed and glaze show significant differences. All ice cases negatively impact the aerodynamic performance by reducing maximum lift, decreasing stall angle and increasing drag.