Affiliations: State Key Laboratory of Turbulence and Complex System,
College of Engineering, Peking University, Beijing 100871, China. E-mail:
qdwei@pku.edu.cn | Department of Computer Science, Johns Hopkins
University, Baltimore, MD 21218, USA | The Institute of Applied Mathematics and Mechanics,
Shanghai University, Shanghai, China | The Key Laboratory of Enhanced Heat Transfer and
Energy Conservation, Ministry of Education of China, College of Environmental
and Energy Engineering, Beijing University of Technology, Beijing, China
Abstract: Through visualization and measurement on the cylinder-plate junction
flow, we show the horseshoe vortices can be significantly modified by altering
the section shape of the cylinder. Both smoke-wire and
Laser-Induced-Fluorescence (LIF) are employed to visualize the vortex
structures. Laser Doppler velocimeter is used to measure the velocity field in
the symmetry plane upstream of the cylinder. Electrical pressure-scanning valve
is applied to acquire the pressure on the plate. It is found that, the sharper
the frontal shape of the cylinder, the closer the vortex shedding position and
the primary horseshoe vortex location to the cylinder. We quantitatively show
the variation of the scale and strength of the primary horseshoe vortex, as
well as the maximum wall shear stress, when the section shape of the cylinder
is varied. The reduced streamwise adverse pressure gradient explains why the
horseshoe vortices are significantly suppressed when the frontal shape of the
cylinder becomes sharper. At last, we present a swept thin cylinder installed
in front of the primary cylinder can be used to suppress the horseshoe
vortices, which is greatly effective and easy to implement.
