Abstract
The authors explained the mechanisms that caused the reciprocating bubble migration with flip-flop phenomenon in a diamond-shaped cylinder bundle. However, it lacks sufficient, quantitative explanation due to complexity in these flows. An experimental study is performed to determine flow instability in the diverging-flow region with flip-flop phenomenon inside diamond-shaped cylinder bundles. The velocity variations in their flow fields were measured using two-dimensional laser Doppler velocimetry(LDV). The study leads to the following disclosures in the diverging region with flip-flop phenomenon: (i) Power spectrum distribution with identical dominant frequency prevails in every row, indicating flow oscillations propagate over the entire passage. (ii) At the third row, the magnitude of power spectra reaches maximum near the "energy supply point", but subsequently diminishes to the minimum value at the apex of the succeeding cylinder. (iii) The flow exhibits the characteristics of a edge tone.
