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ISSN Печать: 1065-3090
ISSN Онлайн: 1940-4336
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WAKE SENSITIVITY OF FLOW OVER A SQUARE CYLINDER WITH RESPECT TO LENGTH OF AN ATTACHED FLEXIBLE WAKE SPLITTER
Краткое описание
The results presented are from an experimental investigation performed for flow over an attached flexible wake splitter on a square prism. The wake structure and flow parameters are captured for different splitter plate lengths at an intermediate Reynolds number. The flexibility is characterized prior to perform the experiments. The time-averaged and instantaneous flow structures are diagnosed by particle image velocimetry (PIV). Apart from the PIV measurement, the hotwire anemometry (constant temperature anemometry, CTA) is also used to obtain vortex shedding frequency using different lengths (L/D = 0.5 to 6) of the wake splitter. It is shown that varying the length of the splitter significantly affects the wake region of the bluff body. Four wake regimes are noticed. For L/D = 0.5, there is increase in the Strouhal number justified by the decrease in wake formation length for the isolated cylinder case. The second regime is for short lengths (0.5 < L/D ≤ 3), where the vortex shedding is suppressed, and the formation length is increased. In the transitional regime (L/D = 4), wake transition takes place due to the interaction between primary vortices and the trailing edge (TE) of the splitter plate. At L/D = 4, TE vortices constructively interact with primary vortices and increase the secondary vortex strength. The secondary vortices are shed due to the Coanda effect, bearing an opposite sense of rotation concerning primary vortices. In the last regime (L/D ≥ 5), the vortex shedding phenomenon is again suppressed due to limited interaction between the primary shear layers. The study is complemented with a flow visualization study showing particle traces of different wake regimes.
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