2D planar jet control for manipulating the separation bubble behind the vertical fence

Abstract

The effect of a 2D planar jet was investigated to manipulate the separation bubble behind the vertical fence. The pulsating and continuous blowing jets were generated in front of or behind the fence. The experiments were carried out in a circulating water channel. The parameters used for controlling the jet included the distance between the slit nozzle and fence, the speed of the jet, and the frequency of the pulsating jet. The velocity fields were measured using phase-averaged DPIV method. From the results, the mechanism of reduction of the separation bubble and the quantitative effects of parameters to reduce the separation bubble behind the fence were found. A maximum reduction of 87% compared with the reattachment length of the uncontrolled fence flow was achieved using the front continuous jet. The controlled fence wakes have higher flow fluctuations and less sheltering effect than that of uncontrolled fence wake.