TY - JOUR
T1 - Analysis of unsteady flow around an axial circular cylinder of critical geometry using combined synchronous measurement in magnetic suspension and balance system
AU - Yokota, Sho
AU - Ochiai, Taku
AU - Ozawa, Yuta
AU - Nonomura, Taku
AU - Asai, Keisuke
N1 - Funding Information:
This work was partly supported by JSPS KAKENHI Grant number 18H03809.
Publisher Copyright:
© 2021, Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2021/1
Y1 - 2021/1
N2 - 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.]
AB - 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.]
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U2 - 10.1007/s00348-020-03101-7
DO - 10.1007/s00348-020-03101-7
M3 - Article
AN - SCOPUS:85098940162
VL - 62
JO - Experiments in Fluids
JF - Experiments in Fluids
SN - 0723-4864
IS - 1
M1 - 15
ER -