VORTEX PAIRING IN A CIRCULAR JET UNDER CONTROLLED EXCITATION - 1. GENERAL JET RESPONSE.

K. B.M.Q. Zaman, A. K.M.F. Hussain

Research output: Contribution to journalArticlepeer-review

261 Scopus citations

Abstract

Hot-wire and flow-visualization studies have been carried out in three air jets subjected to pure-tone acoustic excitation, and the instability, vortex roll-up and transition as well as jet response to the controlled excitation have been investigated. The conditions most favorable to vortex pairing were determined as a function of the excitation Strouhal number, the Reynolds number (Re//D), and the initial shear-layer state. It is shown that the rolled-up vortex rings undergo pairing under two distinct conditions of excitation: ″the shear layer mode″ when the Strouhal number based on the intitial shear-layer momentum thickness is about 0 multiplied by (times) 012, and ″the jet column mode″ when the Strouhal number based on the jet diameter is about 0 multiplied by (times) 85. The trajectories of the vortex centers and their convection velocities during a pairing event have been recorded through phase-locked measurements. Refs.

Original languageEnglish
Pages (from-to)449-491
Number of pages43
JournalJournal of Fluid Mechanics
Volume101
Issue numberpt 3
StatePublished - 1980

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