A dynamic collection efficiency formulation implemented in the icing code DICEPS

Abstract

The Technical University of Braunschweig developed the 2D icing code DICEPS, used for the simulation of ice accretion on aircraft components exposed to icing conditions. In its formulations, DICEPS presents an improvement in the traditional formulation which icing codes use for the calculation of the collection efficiency, which works together with a multi-sub-step algorithm used for the surface deformation during an icing-step. This new formulation continuously updates the impingement mass flow based on the change of the wall-normal as the surface deforms during the multi-sub-step routine in an icing-step, resulting in a dynamic collection efficiency. In the current work, DICEPS and its dynamic collection efficiency formulation (DCEF) are presented and validated through several test cases under three categories: prediction of collection efficiency, rime ice shapes and glaze ice shapes. DICEPS managed to successfully replicate distributions of collection efficiency along with an implemented splashing model. A substantial improvement in the prediction of rime ice shapes via single-step simulations was achieved using the DCEF, while the traditional formulation requires several icing-steps to obtain a converged ice shape. This is also seen when rime ice results are compared to those of FENSAP-ICE, which require as well several icing-steps. In the case of glaze ice, the DCEF presents a time limit since prominent ice features will heavily influence the real collection efficiency, making the DCEF inaccurate after this limit. Nevertheless, the effects that geometrical changes have over parameters such as the heat transfer imply that a multi-step approach is eventually required. By analyzing the results, the DCEF shows that it effectively resembles the physical behavior that geometrical changes impose on the collection efficiency for particles with large inertia, while smaller particles present some inaccuracies, suggesting a proper extension of DCEF for these cases.