Two-cylinder wake with and without tripwires

Abstract

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.This works aims to investigate interference between two tripped cylinders of identical diameter D (= 49 mm), based on measured time-mean drag (CD) and fluctuating drag (CDF) and lift (CLF) at stagger angle a= 0°~ 180° and gap spacing ratio T/D = 0.1 ~ 5, where T is the gap width between the cylinders. Two tripwires, each of 5 mm, were attached on each cylinder at azimuthal angle p = ±30°. Forces on two plain cylinders are also measured and compared with those on tripped cylinders. Flow visualization test was conducted to observe flow structures around the cylinders. CD, CDF and CLF all for the plain cylinders are strong function of a and T/D due tostrong mutual interference between the cylinders, connected to nineteen distinct flow categories including three kinds of tristable flow and five kinds of bistable flow. On the other hand, the tripped cylinders interfere weakly one another, resulting in insignificant variation in forces with a and T/D. Tripwires suppress forces on the cylinders remarkably.