Experimental demonstration of bow-shock instability and its numerical analysis

Y. Kikuchi, N. Ohnishi, K. Ohtani

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

An experimental demonstration was carried out in a ballistic range at high Mach numbers with the low specific heat ratio gas hydrofluorocarbon HFC-134a to observe the unstable bow-shock wave generated in front of supersonic blunt objects. The shadowgraph images obtained from the experiments showed instability characteristics, in which the disturbances grow and flow downstream and the wake flow appears wavy because of the shock oscillation. Moreover, the influence of the body shape and specific heat ratio on the instability was investigated for various experimental conditions. Furthermore, the observed features, such as wave structure and disturbance amplitude, were captured by numerical simulations, and it was demonstrated that computational fluid dynamics could effectively simulate the physical instability. In addition, it was deduced that the shock instability is induced by sound emissions from the edge of the object. This inference supports the dependence of the instability on the specific heat ratio and Mach number because the shock stand-off distance is affected by these parameters and limits the sound wave propagation.

Original languageEnglish
Pages (from-to)423-430
Number of pages8
JournalShock Waves
Volume27
Issue number3
DOIs
Publication statusPublished - 2017 May 1

Keywords

  • Ballistic range
  • Bow-shock instability
  • Supersonic blunt object

ASJC Scopus subject areas

  • Mechanical Engineering
  • Physics and Astronomy(all)

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