Aeroacoustics of a ducted fan ingesting an adverse pressure gradient boundary layer

Feroz Ahmed*, Ismaeel Zaman, Djamel Rezgui, Mahdi Azarpeyvand

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review


The aeroacoustics of a boundary layer ingesting (BLI) ducted fan is investigated experimentally. The study examines a ducted fan immersed in an adverse streamwise pressure gradient turbulent boundary layer developed over a curved wall. Aeroacoustics measurements indicate that the noise from the BLI ducted fan results from a complex interaction among the fan, duct and the incoming boundary layer. The fundamental mechanisms of noise generation are explained using a general source separation strategy. A detailed noise comparison is made at varying fan rotational speeds and across a wide range of axial inflow velocities. In a low thrust regime, the noise is found to be driven by the fan loading, coupled with duct acoustics and the haystacking phenomenon. In a high thrust regime, the contribution from duct acoustics diminishes, and the noise is predominantly driven by the fan loading coupled with the haystacking phenomenon.

Original languageEnglish
Article numberR1
JournalJournal of Fluid Mechanics
Publication statusPublished - 15 Apr 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s). Published by Cambridge University Press.


  • aeroacoustics
  • turbulent boundary layers


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