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Fast identification of transonic buffet envelope using computational fluid dynamics

Jernej Drofelnik (Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK)
Andrea Da Ronch (Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK)
Matteo Franciolini (Department of Energetics, Universitá Politecnica delle Marche, Ancona, Italy)
Andrea Crivellini (Department of Energetics, Universitá Politecnica delle Marche, Ancona, Italy)

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 2 November 2018

Issue publication date: 6 March 2019

149

Abstract

Purpose

This paper aims to present a numerical method based on computational fluid dynamics that allows investigating the buffet envelope of reference equivalent wings at the equivalent cost of several two-dimensional, unsteady, turbulent flow analyses. The method bridges the gap between semi-empirical relations, generally dominant in the early phases of aircraft design, and three-dimensional turbulent flow analyses, characterised by high costs in analysis setups and prohibitive computing times.

Design/methodology/approach

Accuracy in the predictions and efficiency in the solution are two key aspects. Accuracy is maintained by solving a specialised form of the Reynolds-averaged Navier–Stokes equations valid for infinite-swept wing flows. Efficiency of the solution is reached by a novel implementation of the flow solver, as well as by combining solutions of different fidelity spatially.

Findings

Discovering the buffet envelope of a set of reference equivalent wings is accompanied with an estimate of the uncertainties in the numerical predictions. Just over 2,000 processor hours are needed if it is admissible to deal with an uncertainty of ±1.0° in the angle of attack at which buffet onset/offset occurs. Halving the uncertainty requires significantly more computing resources, close to a factor 200 compared with the larger uncertainty case.

Practical implications

To permit the use of the proposed method as a practical design tool in the conceptual/preliminary aircraft design phases, the method offers the designer with the ability to gauge the sensitivity of buffet on primary design variables, such as wing sweep angle and chord to thickness ratio.

Originality/value

The infinite-swept wing, unsteady Reynolds-averaged Navier–Stokes equations have been successfully applied, for the first time, to identify buffeting conditions. This demonstrates the adequateness of the proposed method in the conceptual/preliminary aircraft design phases.

Keywords

Acknowledgements

Da Ronch and Drofelnik gratefully acknowledge the financial support from the Engineering and Physical Sciences Research Council (grant number: EP/P006795/1). Data supporting this study are openly available from the University of Southampton repository at http://dx.doi.org/10.5258/SOTON/D0463

Citation

Drofelnik, J., Da Ronch, A., Franciolini, M. and Crivellini, A. (2018), "Fast identification of transonic buffet envelope using computational fluid dynamics", Aircraft Engineering and Aerospace Technology, Vol. 91 No. 2, pp. 309-316. https://doi.org/10.1108/AEAT-01-2018-0057

Publisher

:

Emerald Publishing Limited

Copyright © 2018, Emerald Publishing Limited

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