This study is focused on volcanic ash ingestion in aircraft engines, that can lead to slow but constant deterioration in engine performance and engine failure because of the mechanical damages to the wall surface. In particular the particles that impact on blades surfaces cause erosion damage and permanent losses in engine performance. Aircraft engine fans could be severely damaged by the ash flow.. In order to clarify the erosion phenomenon the fan has been simulated through the general-purpose CFD code and the numerical simulations were performed using the Reynolds–Averaged Navier–Stokes (RANS). After validating the numerical modeling of the flow without erosion by comparisons with experimental data in literature, a surface injection of a discrete phase has been introduced in order to evaluate particle ingestion of volcanic ash. This phenomenon is a typical gas-particle two-phase turbulent flow and a multi-physics problem where the flow field, particle trajectory and wall deformation interact with among others. A wide experimental investigation has been carried out on an ash sample from Etna volcano. In particular a sieve analysis to obtain particles dimensional distribution and an analysis of SEM images to calculate particles shape factor. These data were used to modeling the particle injection in the CFD model. The numerical investigation was aimed to clarify the effects of particle erosion and to evaluate the change of the flow field in the case of eroded blades. By erosion rate patterns, the eroded mass was estimated and it was used to model the eroded geometry, by a user routine implemented in the dynamic mesh module of the code. So the performances of the damaged fan were estimated and compared with the baseline geometry without erosion.

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