Downstream boundary effects on the spectral characteristics of a swirling flowfield

Y. C. Chao, J. H. Leu, Y. F. Hung, C. K. Lin

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The spectral characteristics and the structural response of a swirling flowfield are investigated subject to a non-axisymmetric disturbance and a contraction imposed downstream. Two natural frequencies are noted in different regions of the undisturbed swirling flowfield, one is due to a precessing vortex core and the other to the most amplified downstream azimuthal instability. The downstream contraction usually causes compression of the central recirculation zone into two side-lobes, increases the dominant frequencies and forms a straight central vortex core with a high axial velocity. The dominant downstream instability frequency depends linearly on the inlet Reynolds number and on the mode of the breakdown. For the downstream non-axisymmetric disturbance, such as the passing of the turbine blades, the fundamental frequency is not altered by the disturbance and the oscillation strength of the downstream instability is greatly reduced as the excitation frequency remains unmatched with the dominant downstream natural frequency. Downstream azimuthal instability promotes the breakdown recirculation.

Original languageEnglish
Pages (from-to)341-348
Number of pages8
JournalExperiments in Fluids
Volume10
Issue number6
DOIs
Publication statusPublished - 1991 Mar 1

All Science Journal Classification (ASJC) codes

  • Computational Mechanics
  • Mechanics of Materials
  • Physics and Astronomy(all)
  • Fluid Flow and Transfer Processes

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