Browsing by Author "Lobuono, Luca"

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    Unsteady aerodynamics of a coupled compact intake-fan in crosswind
    (International Council of the Aeronautical Sciences (ICAS), 2024-10-08) Lobuono, Luca; MacManus, David G.; Christie, Robert; Boscagli, Luca
    The design of aero-engine intakes for compact nacelles can be an important contributor in achieving cruise fuel burn reductions. A key aspect for the design of viable compact intakes is considerations of the off-design crosswind and high incidence conditions. The aerodynamics of compact intakes is also notably dependent on the flow interaction with the fan. This work analyses the unsteady intake-fan interactions under crosswind conditions. The effect of crosswind velocity is evaluated together with the intake ground plane interaction and the unsteady aerodynamic coupling between the intake and fan. The overall aim of the research is to identify the flow structures and the unsteady mechanisms involved in the separation of the intake flow. The work uses an unsteady fully coupled time resolved Reynolds averaged Navier-Stokes computational method to identify the unsteady features of intake-fan flow separation in crosswind operations. The unsteady intake flow distortion is assessed as well as the spectral signatures and engine-order perturbations due to the unsteady flow distortion. Local separated regions were identified in the diffuser. These are associated with the characteristics of the boundary layer and are phase-locked with the local pressure pulses from the fan. This aspect should be considered in the design of compact intakes with relatively high diffusion. Additional assessments of the previously reported unsteady lip separation is provided with the identification of the frequencies of the flow features in post-separation conditions and the axial and azimuthal movement of the separation due to the interaction with the ground vortex.
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    Unsteady flow interactions and ground plane proximity in a coupled compact intake-fan in crosswind
    (Association Aéronautique et Astronautique de France (3AF), 2025-04-01) Lobuono, Luca; MacManus, David G.; Hueso Rebassa, Josep; Christie, Robert
    The assessment of the crosswind flow separation mechanisms and resulting distortion for compact intakes can be a key contributor for the design of viable large civil aeroengines. Under crosswind conditions, the intake aerodynamics are strongly influenced by both the fan and the ground plane. However, the impact of key design parameters, such as ground clearance, on the intake flow distortion is not fully understood. This study investigates the effects of a large variation in ground clearance on the intake-fan unsteady aerodynamics using an Unsteady Reynolds-Averaged Navier-Stokes fully coupled with a rotating fan stage. The work includes an assessment of the unsteady swirl distortion and the unsteady peak distortion events. The findings show that increased ground clearance can have adverse effects for the considered compact intake design. Gross separation can occur at lower crosswind velocities and arise at the intake lower section due to mass flow redistribution. When the ground clearance is increased, the gross separation on the windward side of the intake occurs at a greater crosswind velocity but exhibits greater levels of unsteady intake flow distortion. Overall, intake designs should be assessed at the expected ground clearance as the distortion and the onset of separation can vary substantially.