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Browsing Staff publications (AA) by Publisher "American Institute of Aeronautics and Astronautics (AIAA)"

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    Framework for multi-fidelity simulations of flow interaction and noise of an open rotor
    (American Institute of Aeronautics and Astronautics (AIAA), 2025-01-06) Huang, Guangyuan; Sharma, Ankit; Chen, Xin; Jimeno, Sergio; Riaz, Atif
    Flow-induced noise from open rotor aircraft has received immense research interests as the flow interactions of the components of open rotors lead to significant non-linear features and the flow-induced noise is complicated. Numerical approaches for predicting open rotor flow interactions and the induced noise are in demand without compromising computational accuracy and reducing cost. In this paper, an existing multi-fidelity framework for propeller noise modelling is extended to open rotor configuration. A generic contra-rotating open rotor (CROR) configuration is developed to assess the capability of this multi-fidelity framework. The flow and noise of this configuration are modelled separately in hybrid manner. The flow solution is computed using two methods, which employ unsteady Reynolds average Navier-Stokes (URANS) equations and lattice-vortex method (VLM) at respectively higher- and lower-fidelity levels. Then, the acoustic solution is computed based on the flow solution using Gutin’s method. Results show that transonic features over the rotor blades and significant tip vortices in the wake characterise the CROR flow. Multi-rotor interactions are observed. The aerodynamic loadings are investigated in terms of their mean and fluctuating components. In addition, the far-field noise from the two rotors are compared. The present multi-fidelity framework will be used in future aircraft design which involves open rotor engines. This work is being administered as part of the Innovate UK, Aerospace Technology Institute (ATI) funded research project - ONEheart (Out of Cycle NExt generation highly efficient air transport).
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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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    Wind tunnel installation effects on a high-speed exhaust flow under large blockage
    (American Institute of Aeronautics and Astronautics (AIAA), 2025-05-19) Tsentis, Spyros; Goulos, Ioannis; Debiasi, Marco; Prince, Simon; Pachidis, Vassilios; Zmijanovic, Vladeta; Saavedra, Josè
    This study presents a numerical investigation of wind tunnel installation effects on the exhaust flow for a high-speed system under a blockage ratio of 16.5%. The configuration features a nozzle and a cavity embedded at the base of an ogive-cylindrical body and is representative of future, high-speed exhausts. The work is motivated by the need of testing large, powered-on models and the size of most closed transonic tunnels available in academic research facilities. This combination leads to high blockage ratios and therefore severe flow distortion. The objective is to examine the installation effects and quantify the base flow similarity relative to unbounded conditions. The numerical approach is validated against experimental data. A jet vectoring effect is identified due to the pylon, which is intensified under choked tunnel operation. Additionally, a methodology is proposed, which allows base pressure to be compared to unbounded flow conditions. Results show that the pressure distribution agrees within 1.5% and 0.1% for the base and cavity walls, respectively. This demonstrates that local aerodynamic similarity can be established between large-blockage, tunnel-tested conditions and unbounded flow through the proposed approach. This enables the use of small-scale facilities for base flow studies of high-speed exhausts under large blockage.