Parametric study of separation control over hemisphere using local wall suction in a circulating water channel
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An experimental study on separation control in front of a hemisphere by local wall suction was performed in a circulating water channel. A vortical system engirdling a bluff body was targeted to mitigate its effect on the wake region where hairpin vortices shed. Local wall suction caused a change in the static pressure distribution over the hemisphere surface, moving the flow separation point upstream. As the flow detached early from the hemisphere surface, the size of the wake region increased indicating that it took longer to generate the vortices. Flow visualization using a dye system indicated that the frequency of hairpin vortices in the wake region was reduced by 21 ~ 33 % depending on the hemisphere size when suction ratio was 2.2. The reduction in the vortex shedding frequency was attributed to the weakening of the standing vortices by local wall suction, which resulted in a reduction in the inrush in the wake region.
Abstract
An experimental study on separation control in front of a hemisphere by local wall suction was performed in a circulating water channel. A vortical system engirdling a bluff body was targeted to mitigate its effect on the wake region where hairpin vortices shed. Local wall suction caused a change in the static pressure distribution over the hemisphere surface, moving the flow separation point upstream. As the flow detached early from the hemisphere surface, the size of the wake region increased indicating that it took longer to generate the vortices. Flow visualization using a dye system indicated that the frequency of hairpin vortices in the wake region was reduced by 21 ~ 33 % depending on the hemisphere size when suction ratio was 2.2. The reduction in the vortex shedding frequency was attributed to the weakening of the standing vortices by local wall suction, which resulted in a reduction in the inrush in the wake region.
참고문헌 (17)
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