Suppression of fluid forces on two staggered cylinders

Abstract

An investigation is conducted to suppress flow-induced forces on two identical cylinders (diameter D = 49 mm) at stagger angle α = 0° ∼ 180° and gap spacing ratio T/D = 0.1 ∼ 5, where T is the gap width between the cylinders. In order to suppress fluid forces, two tripwires, each of 5 mm, were attached on each cylinder at azimuthal angle β =±30°. Time-mean drag (CD) and fluctuating drag (C Df) and lift (CLf) on two tripped cylinders were measured and compared with those on plain cylinders. Flow visualization test was also conducted to observe flow structures around the cylinders. CD, C Df and CLf all for the plain cylinders are strong function of a and T/D due to six different interaction mechanisms. On the other hand, the tripped cylinders interfere weakly each other, resulting in insignificant variation in forces with α and T/D. Tripwires suppress forces on the cylinders remarkably.