In recent years, aircraft concepts employing wake-filling devices to reduce mission fuel burn have gained increasing attention. The study presented here aims at a detailed physical understanding of the effects of integrating a propulsive fuselage device on a commercial aircraft. Compared to an isolated, axisymmetric fuselage-propulsor configuration, a propulsive fuselage device experiences an increased circumferential inlet distortion due to three-dimensional geometric features of the aircraft. This study uses three-dimensional CFD simulations to investigate the effect of fuselage upsweep on the aero-propulsive performance of an aircraft configuration featuring a boundary layer ingestion device. It is shown that fuselage upsweep has a negative impact on the performance of a propulsive fuselage device as compared to an axisymmetric configuration. Increasing the upsweep angle by $$\Delta \alpha _{{{\text{SW}},{\text{PFC}}}} = 3.5^\circ$$ Δ α SW , PFC = 3 . 5 ∘ leads to an increase in required fuselage fan shaft power by 19%. Furthermore, it is demonstrated that the negative effects of fuselage upsweep on the propulsor’s performance can be effectively mitigated by a circumferential variation in the propulsor nacelle thickness.

Engine operating cost contributes a major share to an aircraft’s direct operating cost. Thus, the knowledge of the current and future state of their engines is a major concern to any airline operator. To be able to schedule shop visits, state-of-the-art diagnostic and prognostic tools including CFD methods are employed. These RANS-based turbulence and transition models are used to predict the overall efficiency and operational behavior of the engine components. Aerofoil surfaces undergo dynamic change during operation and surface roughness increases in complex non-homogeneous ways due to corrosion, erosion, and fouling processes; depending on the engine component and the environmental condition encountered. The influence of real fouling based roughness on the boundary layer transition is investigated experimentally and numerically within this study. For this purpose, the rotor midspan from the second HPC rotor of the CFM56 is used as the basis for experimental and numerical investigations. Realistic fouling based roughness is applied and investigated both in a cascade tunnel and a low speed compressor rig. The results shown here indicate that laminar boundary layers and their transition to turbulence must be included in the RANS model combination used. Furthermore, it is necessary to consider roughness effects in the respective turbulence and transition model. While the consideration of roughness for the turbulence models has already found wide acceptance, the results in this work motivate the additional extension of the transition model to include roughness effects.