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Browsing Aerospace and Aviation by Subject "4012 Fluid Mechanics and Thermal Engineering"

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    Experimental investigation of unsteady fan-intake interactions using time-resolved stereoscopic particle image velocimetry
    (Elsevier, 2025-07) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David G.; Giannouloudis, Alexandros
    Understanding engine response to unsteady intake flow distortion is a crucial requirement to de-risk the development of novel aircraft configurations. This is more critical for configurations with highly embedded engines. Recent advances in non-intrusive, laser-based flow diagnostics demonstrated the ability to measure unsteady flows in convoluted intakes with high resolution in time and space. This work presents novel non-intrusive, unsteady flow measurements ahead of a fan rotor coupled to a convoluted diffusive intake. The fan rotor caused a local increase of the maximum levels of swirl intensity at the blade tip region, as well as flow re-distribution at the interface plane between the fan and the inlet duct compared to the baseline configuration with no fan in place. This contributed to the reduction of the overall swirl angle unsteadiness across the main flow distortion frequencies. This research presents a notable advance in unsteady fan-intake interaction characterisation. The work shows that high-resolution optical measurements offer notably better understanding of these complex aerodynamic interactions and have the potential to be part of larger scale, industrial testing programmes for future product development and certification.
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    Fundamental concepts of boundary-layer ingestion propulsion
    (American Institute of Aeronautics and Astronautics (AIAA), 2025-05-13) Lamprakis, Ioannis; Sanders, Drewan S.; Laskaridis, Panagiotis
    This work further develops energy-based far-field methods by introducing Galilean covariance in work–energy relationships of flight. The novelty lies in how decomposition formulations are rederived from integral forms of the governing laws applicable to moving control volumes. It is shown that aerodynamic performance is best evaluated in a reference where the aircraft moves through the atmosphere. The advantages are clearly demonstrated through the formulation of a hypothesis on boundary-layer ingestion (BLI) power savings using a series of simplified flat plate–BLI propulsor configurations. This hypothesis links BLI power savings to the energy content within the boundary layer and the propulsor’s ability to attenuate the ingested boundary layer’s velocity profile. Extensive numerical studies on both laminar and turbulent flows are carried out to test this hypothesis, examining different levels of wake recovery achieved through a body force model propulsor with varying load distributions. Near-perfect wake attenuation is shown to yield maximum power savings, but only for higher-Reynolds-number flows, where the influence of aeropropulsive interference on upstream dissipation is minimal. The flat plate findings are extended to a 2D axisymmetric fuselage representation, where baroclinic losses become significant. A maximum power saving of around 8% is achievable at typical cruise conditions for a single-aisle passenger aircraft.
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    Use of non-intrusive flow diagnostics for aero-engine inlet flow distortion measurements in an industrial wind-tunnel
    (AIAA, 2025-01-06) Piovesan, Tommaso; Zachos, Pavlos K.; MacManus, David; Michaelis, Dirk; van Rooijen, Bart; Sheaf, Christopher; Arzoglou, Dimitris
    In crosswind conditions, aero-engine intakes experience unsteady flow distortions at the fan face, typically caused by the ingestion of ground vortices and flow separation. These distortions can negatively impact both intake performance and the compatibility of the downstream propulsion system. Understanding the aerodynamics of these flows is crucial for developing next-generation aircrafts with propulsion systems integrated more closely with the airframe. Optical measurement techniques provide detailed datasets in both space and time to support this understanding, but several challenges limit their widespread use in propulsion integration testing. This study demonstrates a novel application of non-intrusive flow diagnostics in an industrial setting for propulsion integration testing. Optical measurements were conducted within an aspirated intake configuration and, later, within a fully coupled fan-intake propulsion system representative of a modern high-bypass aero-engine. Several innovative solutions were developed to improve the integration of optical systems into industrial settings and enhance data acquisition efficiency. The analysis of the results yielded significant contributions about the unsteady interactions within civil intakes at crosswind and high incidence conditions, which are expected to have a notable impact on the development of future, closely integrated propulsion systems architectures able to meet the specified NetZero targets.