Browsing by Author "Swarthout, Avery E."

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    Aerodynamics of a compact nacelle at take-off conditions
    (IEEE, 2023-06-08) Swarthout, Avery E.; MacManus, David G.; Tejero, Fernando; Matesanz García, Jesús; Goulos, Ioannis; Boscagli, Luca; Sheaf, Christopher
    Next generation ultra-high bypass ratio turbofans may have larger fan diameters than the previous generation of aircraft engines. This will potentially increase the nacelle diameter and may incur penalties to the weight and drag of the powerplant. To offset these penalties, a more compact nacelle may be used. Compact nacelles may be more sensitive to boundary layer separation at the end-of-runway conditions, particularly at an off-design windmilling operating point. Additionally, the flow separation on the external cowl surface is likely to be influenced by the integration between the powerplant, pylon and airframe. The publicly available NASA high lift common research model (HL-CRM) with take-off flap and slat settings was modified to accommodate an ultra-high bypass ratio powerplant. The powerplant has an intake, separate jet exhaust, external cowl and pylon. Boundary layer separation on the external cowl of the compact powerplant is assessed at end-of-runway rated take-off and take-off windmilling scenarios. Additionally, the lift curve and Cp distributions of the high lift common research model (HL-CRM) are compared for rated take-off and take-off windmilling engine mass flows. Overall, the nacelle boundary layer separates from the nacelle highlight at windmilling conditions when the engine mass flow is relatively low. The mechanism of separation at windmilling conditions is diffusion driven and is initiated on the nacelle aft-body. The pylon has a small impact on the overall mechanism of separation. However, the wing and high-lift devices of the HL-CRM introduce local separation on the external cowl. The HL-CRM wing with the installed powerplant stalls at a similar angle (αa/c = 16°) to the HL-CRM with the through flow nacelle available in the open literature. Compared with the nominal take-off condition, the maximum lift coefficient of the HL-CRM airframe was reduced by about 2% under windmilling engine mass flows.
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    Coupled propulsive and aerodynamic analysis of an installed ultra-high bypass ratio powerplant at high-speed and high-lift conditions
    (AIAA, 2023-06-08) Matesanz García, Jesús Matesanz; MacManus, David G.; Tejero, Fernando; Goulos, Ioannis; Hueso Rebassa, Josep; Swarthout, Avery E.; Christie, Robert
    To achieve the targets proposed in the Flightpath 2050 for the aviation industry, more efficient propulsive systems are required. One possible solution is to increase the bypass ratio of the engines to increase the propulsive efficiency and reduce the specific fuel consumption. However, larger fan diameters are expected for these configurations, which results in an increase in the aerodynamic coupling between the powerplant and the airframe. The aim of this work is to develop and demonstrate a thrust and lift matching methodology for installed powerplants using a coupled aero-propulsive model. As a proof of concept, the aerodynamic performance of an ultra-high bypass ratio powerplant integrated with the airframe was evaluated across different flight conditions. This includes high-lift operating conditions such as end of runway; and high-speed conditions such as mid cruise. To evaluate the aerodynamic performance of the propulsion integration a combined assessment of the airframe and powerplant aerodynamics is required using computational fluid dynamics (CFD). The integration of the powerplant with the airframe has the potential to change the engine requirements across the aircraft operational envelope. To account for this the aerodynamic analysis is coupled with a turbomachinery model to adjust the engine thermodynamic conditions at a given operating point.