Author(s): Li Qiang; Zhang Tuqiao; David Z. Zhu
Linked Author(s):
Keywords: Cylinder group; Vortex shedding; Vortex formation; Wake; Flow pattern
Abstract: The flow structure around a cylinder group in cross flow was investigated experimentally. The experiments were conducted in an open channel. The cylinder group was consisted of 19 identical cylinders arranged symmetrically in two concentric circles and one located in the centre. Wake flow structure behind the cylinder group was measured with an Acoustic Doppler Velocimetry. For comparison, the wake flow structure of a single cylinder with an equal diameter to the external diameter of the cylinder group was also measured. The results show that the flow pattern around the cylinder group has some significant differences compared to a single cylinder. There exists vortex shedding behind the cylinder group, and the vortex formation length of the cylinder group is longer than that of a single cylinder. The flow through the gap of the cylinder group plays an import role in the wake, which is the mainly factor causing the differences. The velocity profiles measured along the transverse reveal a larger defect for the case of cylinder group compared to that for a single cylinder. The power spectral density distributions show that the Strouhal number based on the external diameter of the cylinder group is smaller than the that of a single cylinder.
Year: 2013