FENSAP-ICE: A CFD Monte Carlo Approach to Shed-Ice Trajectory and Impact

A fully CFD-based methodology for ice particle tracking based on a Monte Carlo statistical approach and a six-degrees-of-freedom particle-tracking module has been developed within the FENSAP-ICE in-flight icing system. A one-way aerodynamic coupling between the airflow and the ice particle has been adopted, such that the flowfield determines the forces and moments on the particle at each location on its track, but the particle, being much smaller, has no aerodynamic effect on the aircraft's flowfield. A complete envelope of force and moment coefficients has been computed for a representative ice shape, in order to generate a permanent database. At each time step during the integration of the particle track, the angles of the local flow velocity vector with the principal axes of the particle are determined and used to interpolate the corresponding force and moment coefficients from the particle's database. These 6-DOFs are then used to compute the next particle location. The linear displacement is obtained from the integration of Newton's Second Law, whereas angular displacement is obtained from the numerical integration of Euler's equations of motion using quaternions and the 4-stage Runge-Kutta algorithm. A comparison of the aerodynamic force and moment envelope for one ice shape with experimental data will be presented to demonstrate the reliability of this approach. Shed ice particle trajectory computation is demonstrated for a complete aircraft geometry.