Broadband design of acoustic metasurfaces for the stabilization of a Mach 4 boundary layer flow

Rui Zhao, Xiao Liu, Chihyung Wen, Xiaoyong Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

A piecewise acoustic metasurface is designed to suppress the first mode while marginally amplifying the Mack second mode in a Mach 4 flat-plate boundary layer (BL) flow. The results of linear stability theory (LST) and the eN method demonstrate the stabilization effect and transition delay performance, respectively. However, the direct numerical simulation (DNS) results indicate that the designed broadband acoustic metasurface actually weakly excites the first mode with a slightly larger fluctuating pressure amplitude at the surface, which is in contrast to the analysis of LST. The discrepancies are found to lie in the ‘roughness’ effect caused by the recirculation zones inside the microslits and the alternating expansion and compression waves induced at the slit edges, which significantly amplifies the first mode. For further clarification of the competitive mechanism between the acoustic stabilization and ‘roughness’ destabilization effects of metasurfaces on the first mode, a carefully designed metasurface is installed at the maximum growth rate region, which excites the first mode on the metasurface but inhibits its development downstream.

Original languageEnglish
Article number15
JournalAdvances in Aerodynamics
Volume4
Issue number1
DOIs
Publication statusPublished - 6 Apr 2022

Keywords

  • Acoustic metasurfaces
  • Boundary layer stabilization
  • High-speed flow
  • Mack modes

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Aerospace Engineering
  • Mechanical Engineering
  • Renewable Energy, Sustainability and the Environment
  • Modelling and Simulation

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