Predicted Ice Shape Formations on a Boundary Layer Ingesting Engine Inlet 2019-01-2025

Computational ice shapes were generated on the boundary layer ingesting engine nacelle of the D8 Double Bubble aircraft. The computations were generated using LEWICE3D, a well-known CFD icing post processor. A 50-bin global dropsize discretization was used to capture the collection efficiency of water onto the engine nacelle. These discrete results were superposed in a weighted fashion to generate six drop size distributions that span the Appendix C and O regimes. Due to the presence of upstream geometries, i.e. the fuselage nose, the trajectories of the water drops is highly complex. Since the ice shapes are significantly correlated with the collection efficiency, the upstream fuselage nose has a significant impact on the ice accretion on the engine nacelle. These complex trajectories are caused by the ballistic nature of the particles and are thus exacerbated as particle size increases. Shadowzones are generated on the engine nacelle, and move from the bottom to top as particle size increases. The largest particle impinging one the engine nacelle from the 50-bin discretization was the 47 µm dropsize. As a result, the MVD greater than 40 µm Appendix O conditions were characterized by very low collection efficiency on the engine nacelle.