Analysis of unsteady flow around an axial circular cylinder of critical geometry using combined synchronous measurement in magnetic suspension and balance system

Sho Yokota, Taku Ochiai, Yuta Ozawa, Taku Nonomura, Keisuke Asai

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Abstract

Abstract: The wake structure of a freestream-aligned circular cylinder and its aerodynamic characteristics were investigated using a magnetic suspension and balance system (MSBS), which can levitate a model to eliminate support interference. The objectives of the present study were to investigate the flow field around a freestream-aligned circular cylinder and to clarify its effect on the aerodynamic force and base pressure. Experiments were conducted using a 0.3-m MSBS for support-free wind tunnel tests. Six models with fineness ratios (length to diameter, L/D) of 1.0, 1.25, 1.5, 1.75, 2.0, and 2.25 were used. The freestream velocity was set to 10 and 20 m/s, which correspond to Reynolds numbers based on model diameters of 3.3 × 10 4 and 6.7 × 10 4, respectively. The velocity field, aerodynamic force, and base pressure were measured for each freestream-aligned circular cylinder. Two characteristic fluctuations with frequencies of St < 0.05 and St ≈ 0.13 were observed in a nonreattaching flow field. A low-frequency axisymmetric fluctuation related to the drag force and base pressure was observed in the axial direction. A high-frequency antisymmetric fluctuation related to the lift force was observed in the radial direction. These features are in good agreement with those of both recirculation-bubble pumping and vortex shedding observed in the wake of a disk reported in previous studies (Berger et al., J Fluids Struct 4(3):231–257, 1990; Yang et al., Phys Fluids 27(6):064101, 2015). Graphic abstract: [Figure not available: see fulltext.]

Original languageEnglish
Article number15
JournalExperiments in Fluids
Volume62
Issue number1
DOIs
Publication statusPublished - 2021 Jan

ASJC Scopus subject areas

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

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