Key results from the EU H2020 project CENTRELINE are presented. The research activities undertaken to demonstrate the proof of concept (technology readiness level—TRL 3) for the so-called propulsive fuselage concept (PFC) for fuselage wake-filling propulsion integration are discussed. The technology application case in the wide-body market segment is motivated. The developed performance bookkeeping scheme for fuselage boundary layer ingestion (BLI) propulsion integration is reviewed. The results of the 2D aerodynamic shape optimization for the bare PFC configuration are presented. Key findings from the high-fidelity aero-numerical simulation and aerodynamic validation testing, i.e., the overall aircraft wind tunnel and the BLI fan rig test campaigns, are discussed. The design results for the architectural concept, systems integration and electric machinery pre-design for the fuselage fan turbo-electric power train are summarized. The design and performance implications on the main power plants are analyzed. Conceptual design solutions for the mechanical and aero-structural integration of the BLI propulsive device are introduced. Key heuristics deduced for PFC conceptual aircraft design are presented. Assessments of fuel burn, NOx emissions, and noise are presented for the PFC aircraft and benchmarked against advanced conventional technology for an entry-into-service in 2035. The PFC design mission fuel benefit based on 2D optimized PFC aero-shaping is 4.7%.

This paper presents a novel methodology for the design of a gauze that produces distributions of stagnation pressure, swirl angle, pitch angle and turbulence intensity, tailored in both the radial and circumferential directions. A distortion gauze is made from a large number of small-scale circumferential and radial blades with tailored thickness and camber distributions. By controlling the blade design independently in both the radial and circumferential directions, the target inflow pattern can be achieved. 1D correlations are used to initialise the blades and they are refined using full 3D CFD simulations. The final design is additively manufactured for use in rotating rigs. In this paper, the method has been used to reproduce four target inflow patterns with large variations in stagnation pressure and flow angularity. Two examples model the inlet flow distortion seen at the aerodynamic interface plane of an aft-mounted boundary layer ingesting fan. The final two examples model the inlet distortion at inlet to an axial compressor spool caused by upstream structural struts in a swan neck duct. The gauzes are shown to replicate the structures of the target flow in an experimental test. These kind of flow structures would be extremely difficult or impossible to replicate in an experiment in any other way.Graphical abstract

Ultra-high bypass ratio (UHBPR) turbofans offer significant reductions in fuel burn and pollutant emissions due to their higher propulsive efficiency. To minimise drag and weight penalties with larger fan diameters, shorter and slimmer intakes are used. Compact intakes pose a risk of delivering highly distorted flow into the fan when operating at high power in strong crosswind. The fan-distortion interaction can degrade the thrust delivered by the engine, jeopardise the stable operability and threaten the mechanical integrity of the fan. This paper aims to understand the impact of crosswind direction on the aerodynamics of a low pressure ratio fan with both a conventional and a short intake. A fully coupled numerical model of the fan, intake and external flow-field is used to quantify how crosswind direction and intake length impact the loss generation and work through the fan. For crosswind from the left (looking into the engine) the ground vortex is co-rotating relative to the fan direction. This causes co-swirl at the fan tip at entry to the windward lip separation leading to reduced incidence and fan work. In contrast, crosswind from the right causes counter-swirl towards the fan tip as it leaves the separated region, leading to higher work and large corner separations extending down the span. A shorter intake length has a more closely coupled fan and intake lip, which tends to suppress the extent of the windward lip separation, but increases the swirl variations at the casing. This leads to reduced rotor losses for crosswind from the right but increased loss for crosswind from the left. Overall, for a short intake, the fan work is found to be around 6% higher for crosswind from the right relative to crosswind from the left. Despite the large levels of distortion in extreme crosswind, the prototype fan demonstrates in all cases it can operate stably without a significant drop in performance.