FENSAP-ICE Modeling of the Ice Particle Threat to Engines in Flight

A series of turbofan engine malfunctions characterized by flameout and rollbacks at high altitudes have been reported and analyzed by flight safety agencies and concerned industries¹. Conclusions pointed the source of these incidents to be an ice accretion build-up in the low-pressure compressor of the turbofan explained by the presence of ice crystals in the flying environment. In order to provide a numerical tool to analyze such situations, a new capability is developed within FENSAP-ICE² that provides an unsteady model for ice crystals accretion in jet engines. The first step of this study is concentrated on adapting FENSAP-ICE to turbomachinery problems. A 3D unsteady parallel approach for rotor-stator interaction is developed, allowing the treatment of multi-stage blade motion in mixed relative and absolute frames of reference via a finite element interpolation method at interfaces³. The approach is demonstrated using the NASA compressor stage 35. As a first approximation, physical correlations of ice crystals are substituted in the droplet module of FENSAP-ICE, DROP3D, to obtain the unsteady ice crystals impingement zones in a turbomachinery stage, using flux-based collection efficiency. Particular attention is paid to the effects of unsteady rotor-stator interaction across the crystals’ trajectories.