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Future energy-efficient aircraft requires a further drastic reduction in drag and weight. Is it contradictory to improve both at the same time? Is it possible to design a highly efficient HLFC system to be weight-neutral? The present study, performed within the Cluster of Excellence SE 2 A -Sustainable and Energy-Efficient Aviation, summarizes aspects and considerations of the contributing disciplines to derive a solution for a suction-based system on short-range aircraft wings with maximum efficiency, i.e. hybrid laminar flow control application capabilities at minimum weight penalty. Several new features -novel wing design and simulation tools, the potentials of thin plies for weigth saving and the 3D-printing possibilities for ventable core structures -are investigated to achive this goal.

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Hybrid laminar flow control (HLFC) can be a possible solution for future sustainable energy-efficient aviation. The current study proposes a MATLAB-based numerical tool for the design of the suction system for an airfoil optimized for a subsonic short-range HLFC application. Considerable energy losses may occur when the air passes through the perforated metallic outer surface and the inner structure of the suction system. A semi-empirical approach is used to design a layout that provides a target suction velocity based on measured pressure losses through porous medium and substructures. Flowbench measurements were performed on 3D-printed internal core test samples to quantify the pressure losses that can be used to create a lower pressure below the porous sheet matching the target suction velocity. The actual suction realized on the airfoil using this substructure concept has a discrete nature that increases with the distance between two adjacent walls. Finally, the suction system’s power requirement is calculated. The power requirement for distributed suction accounts for the pressure loss characteristics of the porous material, the internal core structure, and throttling holes. However, the study does not include the ducting losses from the substructure to the compressor. Approximately 80% of the total suction power is utilized to eject the sucked air back to the freestream conditions for a system with a compressor and propulsive system efficiency equal to one. The study analyses the performance of the designed internal core layout to different flight conditions and addresses the suction power requirement variation with lift coefficient and flight altitude.