Extension and application of the Eigen analysis in general curvilinear coordinates method for acoustic propagation in aero-engine intakes

Abstract

Numerical methods are utilised in the industrial design process of aero-engines to model the acoustic properties of proposed designs. The Eigen Analysis in General Curvilinear Coordinates (EAGCC) method is a numerical method developed to predict acoustic propagation in aero-engine ducts. This PhD thesis aims to validate and develop the EAGCC method such that it can be used to predict the far-field linear acoustic propagation from a representative fully three-dimensional aero-engine intake. This has been demonstrated by applying the method to a non-axisymmetric intake and cross-validated against published ACTRAN/TM results. The cross-validation includes predictions of induct and far-field propagation for both hard wall and lined configurations. The extension of the method has led to the development of guidance to rationalise the modal classification approach for non-axisymmetric intakes and to the re-formulation of the propagation framework for lined cases to reduce the impact of liner discontinuity. A comprehensive error analysis study has identified the mechanisms by which mesh-related error occurs. Two local error terms have been derived, quantified, and validated in one dimension. Further efforts have been made to explore ways of developing the method that broadens future applicability within the industrial design process. Progress towards this goal includes the reduction in computation time through the parallelisation of the generalised eigenvalue problem formulation and the introduction of a new approximation method for predicting sensitivities to small changes in mean flow.

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Identifiers

ORCID for Alan Mcalpine: orcid.org/0000-0003-4189-2167

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