A study of the effect of serration shape and flexibility on trailing edge noise: Physics of Fluids

P. Zhou, Q. Liu, S. Zhong, Y. Fang, X. Zhang

Research output: Journal article publicationJournal articleAcademic researchpeer-review


In this study, we investigated the performance of flexible trailing edge serrations of various shapes for airfoil self-noise reduction through anechoic wind tunnel experiments. A flat plate model was tested at zero angle of attack. The chord-based Reynolds number was between 1.6 × 105 and 4 × 105. The boundary layers were fully tripped near the leading edge. Add-on type trailing edge serrations were cut from flexible polyethylene terephthalate sheets. It is observed that compared with rigid serrations, flexible serrations can achieve an additional broadband noise reduction up to 2 dB-3 dB at high frequencies, and the effect also depends on the geometry of the serrations. Complementary deformation measurement and aerodynamic force measurement show that flexible serrations can align better with the flow and are expected to reduce the crossflow intensity near the serration roots, which has been related to the extraneous high-frequency noise generated by serrations in previous studies. An inviscid model is proposed to predict the wake structure and the loadings for serrations of various shapes. Although the model over-predicts the crossflow speed due to the omission of the viscous effect, the relative intensity corresponding to different serration geometry is consistent with experimental observations. Last, we show that the recent analytical noise prediction model [B. Lyu and L. J. Ayton, "Rapid noise prediction models for serrated leading and trailing edges,"J. Sound Vib. 469, 115136 (2020)] for a serrated trailing edge still significantly overpredicts the noise reduction capacity by serrations and does not reveal the role of serration shape properly. This indicates the necessity to include the non-frozen turbulent properties near serrations in the future prediction models. © 2020 Author(s).
Original languageEnglish
JournalPhys. Fluids
Issue number12
Publication statusPublished - 2020


  • Acoustic noise measurement
  • Angle of attack
  • Boundary layers
  • Forecasting
  • Noise abatement
  • Plastic bottles
  • Reynolds number
  • Wind tunnels
  • Aerodynamic force measurements
  • Anechoic wind tunnels
  • Chord-based Reynolds number
  • Deformation measurements
  • Noise prediction models
  • Self noise reduction
  • Serrated trailing edges
  • Turbulent properties
  • Predictive analytics


Dive into the research topics of 'A study of the effect of serration shape and flexibility on trailing edge noise: Physics of Fluids'. Together they form a unique fingerprint.

Cite this