Parametric design of non-axisymmetric separate-jet aero-engine exhaust systems

John J Otter,Robert Christie,Ioannis Goulos,David G Macmanus,Nicholas Grech

doi:10.1016/j.ast.2019.05.038

John J Otter, Robert Christie + Show 3 more

Open Access

https://doi.org/10.1016/j.ast.2019.05.038

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Abstract

Future 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.

Highlights

The reduction of engine specific fuel consumption (SFC) is a major focus in the design and development of aero-engines: the aerodynamic performance of the exhaust system is central to this aim
Future engines are expected to operate with low Fan Pressure Ratios [1], high bypass ratios (BPR) [2] and low specific thrust in order to increase propulsive efficiency and reduce specific fuel consumption (SFC) [3]
This paper has presented a novel design and analysis method for non-axisymmetric aero-engine exhaust systems

Summary

Introduction

The reduction of engine specific fuel consumption (SFC) is a major focus in the design and development of aero-engines: the aerodynamic performance of the exhaust system is central to this aim. Future engines are expected to operate with low Fan Pressure Ratios [1], high bypass ratios (BPR) [2] and low specific thrust in order to increase propulsive efficiency and reduce specific fuel consumption (SFC) [3]. The primary aim of much of the previous research into single stream non-axisymmetric exhaust nozzles is on the enhancement of jet mixing [5,6,7] with multiple applications to military aircraft demonstrated [8,9,10]. The impact of non-axisymmetric designs on the aerodynamic performance of a separate-jet exhaust nozzle has not yet been reported in the open literature

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