Rotor Wake Modifications in Hover Using Tangential Spanwise Blowing Over a Rounded Blade Tip

Tangential spanwise blowing over a rounded blade tip is computationally investigated as an active technique for modifying the structure of the tip vortex core as well as for increasing blade vortex miss distance. This paper is focused on the CFD analysis of rotor flow for the blowing configuration compared with the baseline case of a hovering rotor with rounded blade tip. The mechanisms of formation and convection of rotor blade tip vortices up to and beyond 360 degrees wake age are described, based on the CFD results for both cases. Computational results, obtained in near and far wake, show that, through the spanwise blowing the vortex trajectory is modified with a descent wake rate significantly higher and contraction rate lower than in the baseline case. The contraction and descend rates of the rotor wake are numerically estimated and used as an indicator of potential benefit for BVI noise reduction. Additionally, the numerical results indicate a higher dissipation of the vorticity.