13th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

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Yaozhi Lu - Imperial College London
Bharat Lad - Rolls-Royce plc
Jeff Green - Rolls-Royce plc
Mehdi Vahdati - Imperial College London
Sina Stapelfeldt - Imperial College London


Due to manufacturing tolerance and deterioration during operation, fan blades in the same engine exhibit geometric variability. The absence of symmetry will inevitably exacerbate and contribute to the complexities of running geometry prediction as the blade variability is bound to be amplified by aerodynamic and centrifugal loading. In this study, we aim to address the fan blade untwist related phenomenon known as Alternate Passage Divergence (APD). As the name suggests, APD manifests as alternating passage geometry (and hence alternating tip stagger pattern) when the fan stage is operating close to/at peak efficiency condition. APD can introduce adverse influence on fan performance, aeroacoustics behaviour, and high cycle fatigue characteristics of the blade. The main objective of the study is to identify the parameters contributing to the APD phenomenon. In this study, the APD behaviours of two transonic fan blade designs are compared.

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