Effect of boundary layer trip on reduction of jet noise in over-expanded nozzle flow

Masayuki Anyoji, Issei Tabaru

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


A flow resonance accompanied by the emission of acoustic tones occurs in an over-expanded convergent-divergent (C-D) nozzle when operated at comparatively low pressure ratios. This phenomenon is distinguished from conventional screech tones and is referred to as “transonic tones”. In contrast to screech tones, the peak resonant frequency for transonic tones increases with pressure ratio; the peak sound pressure level exceeds 110 dB. In this study, we investigated the basic characteristics of transonic resonance and tones using a circular C-D nozzle in an anechoic room. The effects of the boundary layer trip were also evaluated using a tripping wire for the suppressing transonic resonance and tones. The results of acoustic measurements show that several predominant peaks correspond to transonic tones. However, the boundary layer trip inside the nozzle effectively eliminated these tones and suppressed the unsteadiness of the flow inside the nozzle.

Original languageEnglish
Pages (from-to)448-452
Number of pages5
JournalJournal of Thermal Science
Issue number5
Publication statusPublished - Oct 1 2017

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics


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