Numerical Simulation of Ice Crystal Accretion Inside an Engine Core Stator

A CFD simulation methodology is presented to calculate blockage due to ice crystal icing of the IGV passages of a gas turbine engine. The computational domain consists of six components and includes the nacelle, the full bypass and the air induction section up to the second stage of the low-pressure compressor. The model is of a geared turbofan with a fan that rotates at 4,100 rpm and a low-pressure stage that rotates at 8,000 rpm. The flight conditions are based on a cruising speed of Mach 0.67 in Appendix-D icing conditions with an ice crystal content is 4.24 g/m³. Crystal bouncing, and re-entrainment is considered in the calculations, along with variable relative humidity and crystal melting due to warmer temperatures within the engine core. Total time of icing is set to 20 seconds. The CFD airflow and ice crystal simulations are performed on the full 6-stage domain. The initial icing calculation determines which stage will be chosen for a more comprehensive analysis. In this case the IGV passage was chosen for the detailed multi-shot analysis, where the computational grid is frequently updated to reflect the changes in surface and increasing blockage in the domain. The starting number of grid points in the entire system is approximately 8 million and increases with the remeshing of the iced IGV surfaces. Results show that accretion in the IGV does have an impact as it increases the bypass ratio and reduces the core efficiency. The methodology was shown to be effective in demonstrating an automated workflow for engine icing assessment studies.