Browsing by Author "Ramirez-Rubio, Santiago"

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    Aerodynamics of high-bypass-ratio aeroengine nacelles: numerical and experimental investigation
    (American Institute of Aeronautics and Astronautics (AIAA), 2025-03-12) Tejero, Fernando; MacManus, David G.; Sanchez-Moreno, Francisco; Schreiner, Deneys; Hill, Andrea; Sheaf, Christopher T.; Ramirez-Rubio, Santiago
    This work presents a numerical and experimental investigation of the nacelle aerodynamics for high-bypass- ratio aeroengines. A conventional nacelle that is representative of a current standard, and a compact design that is envisaged for future aeroengines, were optimized with an existing computational method. Both nacelles were tested in a large-scale transonic wind tunnel. For the first time, the aerodynamic benefits of compact nacelles are demonstrated through an experimental test campaign. Measurements and computational fluid dynamics (CFD) simulations confirmed the drag reduction of compact configurations across a wide range of operating points with different flight Mach numbers, mass-flow capture ratios, and angles of attack. For midcruise conditions with a Mach number of 0.85, this was a drag reduction of 8.5% and 8.8% for the measurements and CFD, respectively. These benefits are similar to an isolated optimization, that is, not installed in the wind tunnel, which confirmed the capabilities of the method to identify the drag benefit of compact designs. Relative to the measurements, the main aerodynamic characteristics on the nacelles were captured by CFD in terms of isentropic Mach number distributions and shock location. This work provides a quantitative evaluation for the use of CFD within an industrial setting for nacelle design and analysis.
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    Framework for estimation of nacelle drag on isolated aero-engines with separate jets
    (Sage, 2020-05-08) Ramirez-Rubio, Santiago; MacManus, David G.
    Typically, the evaluation of nacelle drag in preliminary design is required to find an overall optimum engine cycle and flight trajectory. This work focuses on the drag characteristics of aero-engine nacelles with separate jet exhausts. The main body of analysis comes from 3D numerical simulations. A new near-field method to compute the post-exit force of a nacelle is presented and evaluated. The effects of the engine size, Mach number, mass-flow capture ratio and angle of attack are assessed. The results obtained from the numerical assessments were used to evaluate conventional reduced order models for the estimation of nacelle drag. Within this context, the effect of the engine size is typically estimated by the scaling ratio between the maximum areas and Reynolds numbers. The effect of the angle of attack on nacelle drag is mostly a function of the nacelle geometry and angle of attack. In general, typical low order models based on skin friction and form factor can underestimate the friction drag by up to 15% at cruise operating point. Similarly, reduced order models based solely on Reynolds number and Mach number can underestimate the overall nacelle drag by up to 74% for free stream Mach number larger than the drag rise Mach number.