Aerodynamic Characteristics of Two Airfoils with Critical Ice Shapes

Aerodynamic characteristics of the transport aircraft with critical ice shapes should be predicted before flight test in order to be satisfied with the requirements of airworthiness for flight safety in icing condition. Computational fluid dynamics (CFD) method is used to investigate aerodynamic characteristics of two airfoils (NACA23012 and a business jet airfoil) with critical ice shapes formed in icing wind tunnel. First, the appropriate turbulence model and computational grid are validated by comparison of the result of computation and experiments. Next, the analysis of aerodynamic forces of the two airfoils with and without critical ice shape is executed. It is shown that in the same angle of attack, the lift and drag of the airfoil decreases and increases largely, respectively, and the maximum lift-drag ratio becomes smaller because of ice accretions. It is different that the pressure contributes to the lift and the drag of the airfoils with and without critical ice shapes. The airflow separated from both upper and lower surface in the leading edge is appearance at small angle of attack and develops to the trailing edge with increased angle of attack due to ice accretions. It is the reason that aerodynamic characteristics become worse.