Wind tunnel effects on ice accretion over aircraft wings

Reference ice accretion experiments are reproduced numerically using the simulation framework PoliMIce to investigate solid blockage effects and wall-model boundary layer interaction at the wall-model juncture. The open-source OpenFOAM software is applied to the computation of the aerodynamic flow-field and of the trajectories of water droplets. The thickness of the iced layer is then determined using the PoliMIce ice accretion module, which solves the multi-phase—ice, liquid water and air—flow around the body surface. The iced geometry is updated in the aerodynamic solver to compute the aerodynamic forces, heat transfer and drop trajectories around the iced wing. The iterative process is carried out for the duration of the experiments. Wind tunnel wall effects are investigated for diverse operating conditions. Blockage effects on the measured lift coefficient of a twodimensional iced airfoil result into a variation of the corrected angle of attack during the experiment, due to the modification of the airfoil shape in time introduced by the accreting ice. Finally, icing tests on three-dimensional straight and swept wings are simulated. Water droplets impingement is heavily affected by flow separation at the juncture between the tunnel wall and the model wing: a shadow region where droplets do not hit the wing surface is observed. In pure rime icing conditions, the shadow region is free of ice. In glaze or mized rime-glaze conditions, instead, an ice build-up within the shadow region occurs, due to shear stresses driving the liquid film towards the wall-model juncture. Numerical results compare fairly well with available experimental data on ice accretion.