Broadband trailing edge noise reduction through porous velvet-coated serrations

Peng Zhou, Siyang Zhong, Xiangtian Li, Yuhong Li, Wangqiao Chen, Hanbo Jiang, Xin Zhang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

10 Citations (Scopus)


This study experimentally investigates the potential of using combinations of trailing edge serrations and thin porous membrane/velvet structures for turbulent boundary layer trailing edge noise reduction. The experiments were conducted in an anechoic wind tunnel, with a flat plate model as the baseline model. The chord-based Reynolds number ranged between 2 × 10 5 and 5 × 10 5, and the boundary layers were fully tripped near the leading edge. Two different installation methods were tested, where the serration structure was aligned/misaligned with the undisturbed wake flow. It was observed that the noise reduction capability of the conventional serrations deteriorates significantly when the serrations are misaligned with the flow, while the performances of the combined structures are only slightly affected by flow misalignment. A novel combined treatment is developed, in which the trailing edge serrations are surrounded by serrated porous velvet structures. This treatment is found to outperform the unmodified serrations and can achieve approximately 10 dB noise reduction in both flow-aligned and flow-misaligned conditions, within a wide frequency range corresponding to a boundary layer thickness-based Strouhal number St δ between 0.3 to 1. A 30%-40% increase in the aerodynamic drag due to the velvet structures was observed. Further hotwire wake survey revealed the possible mechanisms for the additional noise reduction capability of the combined treatments.

Original languageEnglish
Article number057112
JournalPhysics of Fluids
Issue number5
Publication statusPublished - 1 May 2022
Externally publishedYes

ASJC Scopus subject areas

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


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