An Aerodynamic Analysis of a Robustly Redesigned Modern Aero-Engine Fan

TL;DR

This study uses computational methods to redesign a modern aero-engine fan, making it more resistant to leakage flow effects by analyzing aerodynamic changes that improve performance and stability under seal erosion conditions.

Contribution

The paper introduces a novel aerodynamic redesign of a fan stage that reduces sensitivity to leakage flows using advanced optimization and flow analysis techniques.

Findings

Redesigned fan shows increased insensitivity to leakage flows.

Flow re-acceleration prevents corner separation.

Reduced cross-passage pressure gradient improves robustness.

Abstract

This paper documents results from a recent computational study aimed at de-sensitizing fan stage aerodynamics---in a modern, high bypass ratio aero-engine---to the effects of rear-seal leakage flows. These flows are the result of seal erosion between a rotor and stator disk in an engine, and deterioration over the life of an engine. The density-matching technique for optimization under uncertainty was applied to this problem. This involved RANS and adjoint flow solves of a full fan stage carried out at two different leakage conditions. Here a detailed analysis of the fan stage aerodynamics is carried out to determine why exactly the new design is more insensitive to the effects of leakage flows. Specifically, it is shown that this insensitivity is attributed to three main factors: a slight rearward shift in loading, and thus a reduction in incidence; a reduction in the cross-passage pressure gradient; and a re-acceleration of the flow towards the trailing edge, which prevented any corner separation.