Influence of Engine Exhaust on Wing Underside Flow for a Passenger Aircraft

  • Mueller, Jan (The University of Electro-Communications)
  • Chiba, Kazuhisa (The University of Electro-Communications)
  • Oba, Yoshinori (IHI Corporation)

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Modern aircraft are usually equipped with engines that feature a large bypass ratio and therefore a large diameter, with engine exhaust and surrounding flow significantly influencing the flow field around the aircraft wing and fuselage. With the current approach of isolated design processes for both airframe and engine, these aerodynamic influences are rarely represented accurately, as the interaction models are often simplified (e.g. flow-through nacelle, artificially modelled inlet air distribution). However, to achieve the optimal design for a future aircraft, an accurate way to predict these influences is necessary. In this study, we conducted an integrated analysis of an aircraft airframe together with an operating engine to directly capture the interaction phenomena caused by engine spill and exhaust. The airframe is based on the NASA Common Research Model (CRM) with wing, body, nacelle and pylon (wbnp), while the engine bypass is modelled in detail with the fan rotor based on NASA Rotor67. Airframe and rotor were discretized separately with an unstructured mesh to accommodate the complex geometry and interaction between the domains is facilitated via the overset mesh method. Computation was carried out for 8 + 17/22 rotations of the fan. However, the time scales of the phenom- ena at each domain are too different: As this limits the speed of our integrated calculation, we terminated the analysis here. Accordingly, the mass flow rate inside the nacelle has not yet achieved sufficient con- vergence. Nonetheless, significant interaction phenomena can already be observed: The engine exhaust is pulled towards the wing underside and enlarged regions of supersonic flow impact lift.