Browsing by Author "Otter, John J."
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Item Open Access Aerodynamic analysis of civil aeroengine exhaust systems using computational fluid dynamics(AIAA, 2018-06-25) Otter, John J.; Goulos, Ioannis; MacManus, David G.; Slaby, MichalAs the specific thrust of civil aeroengines reduces, the aerodynamic performance of the exhaust system will become of paramount importance in the drive to reduce engine fuel burn. This paper presents an aerodynamic analysis of civil aeroengine exhaust systems through the use of Reynolds-averaged Navier–Stokes computational fluid dynamics. Two different numerical approaches are implemented, and the numerical predictions are compared to measured data from an experimental high-bypass-ratio separate-jet exhaust system. Over a fan nozzle pressure ratio range from 1.4 to 2.8, a comparison is drawn between values of the thrust coefficient calculated numerically and those obtained from experimental measurements. In addition, the effects of the freestream Mach number and extraction ratio on the aerodynamic behavior of the exhaust system are quantified and correlated to fundamental aerodynamic parameters.Item Open Access Design and analysis of non-axisymmetric installed aero-engine exhaust systems(Elsevier, 2020-09-17) Otter, John J.; Goulos, Ioannis; Christie, Robert; MacManus, David G.In order to increase propulsive efficiency, and hence reduce fuel consumption, future aero-engines are expected to operate with higher bypass ratios and larger fan diameters relative to current in-service engines. As such, propulsion systems are likely to be more closely-coupled with the airframe which is expected to accentuate detrimental aerodynamic interference effects between the engine and airframe. It is therefore crucial that the design of future aero-engine exhaust systems is considered as part of an engine-airframe configuration in order to ensure that the expected benefits of high BPR engines are realised. This work presents the aerodynamic performance and evaluation of a set of novel exhaust systems within complete engine-airframe configurations. The introduction of non-axisymmetric exhaust systems was shown to mitigate the aerodynamic penalties associated with closely-coupled propulsion systems at cruise conditions. Relative to an axisymmetric baseline configuration, the introduction of non-axisymmetric bypass and core nozzles were found to increase the net vehicle force of the engine-airframe configuration by 0.8% and 0.6% respectively. As a result of this work, it can be concluded that non-axisymmetric exhaust systems represent a viable method for reducing aircraft cruise fuel burn.Item Open Access Multi-fidelity assessment of exhaust systems for complete engine-airframe integrations(Unknown, 2020-02-28) Hueso Rebassa, Josep; Tejero, Fernando; Otter, John J.; Goulos, Ioannis; MacManus, David G.For podded underwing configurations, the goal of specific fuel consumption reduction has led to engine designs with larger fan diameters and higher bypass ratios to increase propulsive efficiency. As a consequence of this trend, the aerodynamic interference with the airframe is increased. Non-axisymmetric exhaust geometries could minimise such interference for coupled configurations. Class Shape Transformation functions are used to define 3D podded engine geometries that are installed on a transonic aircraft configuration. The complete system is assessed at mid-cruise conditions of a representative long-range cruise operation. The assessment is conducted by multi-fidelity computational fluid dynamics computations that are Euler inviscid and Reynolds Averaged Navier Stokes turbulent methods. The correlation between the different fidelities is analysed and a multi-fidelity co-kriging model is developed. The model is applied to predict the behaviour of installed non-axisymmetric exhaust systems and results into a 33% computational benefit compared to single-fidelity surrogates.Item Open Access Parametric design of non-axisymmetric separate-jet aero-engine exhaust systems(Elsevier, 2019-07-16) Otter, John J.; Christie, Robert; Goulos, Ioannis; MacManus, David G.; Grech, NicholasFuture civil air vehicles are likely to feature propulsion systems which are more closely integrated with the airframe. For a podded underwing configuration, this close coupling is expected to require non-axisymmetric design capabilities for the aero-engine exhaust system. This work presents the development of a novel parametric representation of non-axisymmetric aero-engine exhaust system geometries based on Intuitive Class Shape Transformation (iCST) curves. An exhaust design method was established and aerodynamic analyses of a range of non-axisymmetric configurations was demonstrated. At typical flight conditions, the introduction of non-axisymmetric separate jet nozzles was shown to increase the engine net propulsive force by 0.12% relative to an axisymmetric nozzle.