Vortical Inflow Distortion in a Jet Engine Intake During Take-Off

Abstract

The effects of inlet distortions arising from the interaction between the ground boundary layer and the flow into a jet engine intake during ground operation and take-off is examined using computational fluid dynamics (CFD). Steady state numerical simulations using the German Aerospace Center (DLR) in-house CFD-solver TRACE are conducted in order to identify the dependency of the interactions on parameters like mass flow through the engine and far-field Mach number. Object of the study is the nacelle and inlet duct of an International Aero Engines (IAE) V2500, a typical jet engine for a single aisle aircraft. For an axial inflow into the simulation domain, the variation of inflow velocity and mass flow through the engine exposes three different configurations of the inflow distortion: undistorted inflow (no vortical structures in the intake section of the engine), distorted inflow with one dominant vortex in the lower part of the engine intake and one form of distorted inflow with two counter-rotating vortices. The undistorted inflow is associated with a low mass flow through the engine when not the entire boundary layer upstream of the engine is ingested into the intake. Higher mass flows result in a vortex system with two counter-rotating vortices in the lower part of the engine intake. Simulations with cross-flow show an interaction between the inlet distortion from the ground interaction and the effects of the cross-flow inside the nacelle resulting in a complex 3D-flow. This study is a preliminary study for further investigations that will combine a full annulus model of the engines fan stage and the booster stage IGVs with the existing model of the nacelle, the inlet duct and the far field. The focus of these future investigations will be the analysis of the influence of inflow distortions on the aerodynamics of the fan. This interaction is of particular interest regarding the possible integration of jet engines into the airframe of future aircraft concepts like blended wing bodies or flying wings.