EXPERIMENTAL STUDY OF DRAG REDUCTION BY USING A ROTATING TUBE WITHIN A STAGGERED TUBE BUNDLE ARRANGEMENT

As a fluid flows through a tube bundle, various stresses are exerted on cylinders, which often leads to a variety of problems. The aim of this study is to investigate experimentally the active flow control by using a rotating tube within the bundle. The latter is composed of nine horizontally staggered cylinders with an equal longitudinal and transverse pitch-to-diameter ratio of <i>P/D</i> = 2.24. The experiments were conducted in a subsonic wind tunnel in order to understand the effect of one rotating cylinder on adjacent stationary cylinders. Measurements are performed for a bundle containing only stationary tubes and another containing only one rotating tube. Reynolds numbers calculated based on tube diameter are 0.393 × 10<sup>5</sup> and 0.786 × 10<sup>5</sup>, and therefore subcritical flow regime is adopted. Heat transfer between fluid and tubes is not considered in this study. The values of pressure drag and lift coefficients acquired from measurements are compared with those characterizing flows across a stationary tube bundle.