Browsing by Author "Lamprakis, Ioannis"

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    Energy-based aerodynamic loss and recovery characteristics of adiabatic and heated fuselages
    (AIAA, 2023-06-07) Lamprakis, Ioannis; Sanders, Drewan S.; Laskaridis, Panagiotis
    An energy-based aerodynamic analysis of the mechanical loss generation and potential energy/exergy recovery mechanisms is carried out for adiabatic and heated 2D axisymmetric flows over fuselage-shaped axisymmetric bodies. A generality of these mechanisms is obtained from dimensional analysis by appropriately scaling the freestream Reynolds and Mach numbers, while varying a reference fuselage’s fineness ratio. Thermo-aerodynamic implications and synergies of boundary-layer heating on the loss distribution, energy, and heat exergy recovery potentials are further considered for varying wall temperature ratios. The result is a clear identification of partial dynamic similarity and heat transfer effects on flow mechanisms such as shear layers, separation bubbles, and shockwaves of axisymmetric flows, and subsequent implications on loss distribution and energy recovery characteristics relating to boundary-layer ingestion. The analysis indicates that dissipating heat from aircraft surfaces aids, circumstantially, to drag reduction of unpowered fuselage bodies and increases, relative to the adiabatic, the recoverable energy fraction available for the boundary-layer ingestion propulsor, by strategically manipulating the loss distribution, while removing excess heat from the aircraft’s subsystem (batteries, fuel cells). Finally, an approach to assess the feasibility of exergetic heat recuperation as a possible means of useful work extraction and improved aerodynamic performance is explicitly introduced and discussed in the paper.
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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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    Potential for energy recovery of a nonadiabatic subsonic airfoil
    (American Institute of Aeronautics and Astronautics (AIAA), 2025) Lister-Symonds, Joseph E.; Mutangara, Ngonidzashe E.; Lamprakis, Ioannis; Sanders, Drewan S.
    This paper investigates the effect of wall temperature and flow conditions on the potential for energy recovery of the NACA0012 airfoil. A work–energy balance has been derived from the governing equations for moving control volumes for a body in dynamic equilibrium, aerodynamically decoupled from its propulsive source. The formulation has been applied to an extensive test matrix of computational fluid dynamics cases, with steady level flight imposed and wall temperature, angle of attack, Reynolds number, and Mach number varied independently. The decomposition of the wake energy shows explicitly that the near-field work of the body manifests as global energy constituents, viscous dissipation, and baroclinic work. The analysis identifies the conditions and underlying mechanisms that minimize and maximize the potential for energy recovery, revealing that there are synergistic opportunities for tightly coupled airframe and propulsor configurations with waste heat to reject.