Asymmetrical Boundary Layer Separation at the Base of a Two Cylinder Geometry

This paper reports on the experimental description of the three-dimensional horseshoe vortex system occurring at the base of two cylinders mounted side by side on an endwall. The spacing between the two cylinders is adjusted to generate a family of viscous flows. Flow visualization performed in a water tunnel provides a qualitative understanding of the flow over a range of flow variables. A detailed wind tunnel experiment, provides a quantitative description of the flow at a single test condition. The flow is described by the use of a five-hole pressure probe and by cylinder and endwall surface static pressure measurements. At Re_D = 2.5 × 10⁵ the measurements show an asymmetrical primary vortex with a wide flat cross section. A small counter rotating vortex is found between the primary vortex and the cylinder leading edge.