Strengths of horseshoe vortices around a circular cylinder with an upstream cavity

Abstract

Horseshoe vortices are formed at the junction of an object immersed in fluid-flow and endwall plate as a result of three-dimensional boundary layer separation. This study presents the variation of the strengths of such horseshoe vortices around a circular cylinder with a cavity (slot) placed upstream. Through the cavity, no mass flow addition (blowing) or reduction (suction) is applied. With the upstream cavity, adverse pressure gradient is weakened upstream of the cavity whereas it is strengthened downstream of the cavity. Furthermore, a single vortex system is found to form immediately upstream of the cylinder instead of a typical two vortex (primary and secondary vortices) system observed in the absence of the upstream cavity. The strength of the primary vortex is weakened due to the fluid stream engulfed in to the upstream cavity, resulting in diffusion of the mainstream. Consequently, the circulation of the primary vortex is weakened.

Theoretical Investigation of Passive Horse-Shoe Vortex

“…Also, Kubendran et al [8] performed experiments on leading-edge swept fairings by considering turbulent flow around a wing/fuselage-type juncture. K. Kang et al [9] used an upstream cavity to increase the momentum within the BL to face the recirculated flow and found that only one vortex formed instead of a set of vortices. Philips et al [10] and D. Barberis et al [11] used suction to eliminate HSV in which the BL, which is the main source of HSV, was sucked.…”

Effects of an upstream triangular plate on the wing-body junction flow

“…Consequently, it prevented the formation of horseshoe vortices in front of the leading edge [2]. They, however, reported that weak vortex legs might still form downstream of the nose region due to the skew- proposed by Kang et al (2009) was shown to decrease the strength of the horseshoe vortex [9]. Kairouz and Rahai (2005) proposed using longitudinal triangular riblets within a turbulent boundary layer upstream of a wing-body junction.…”