EXPERIMENTAL INVESTIGATION OF DRAG REDUCTION IN ANNULAR TWO-PHASE FLOW OF OIL AND AIR.

In this study the effect of the presence of a drag reducing agent (DRA) on the pressure drop in cocurrent horizontal rough pipes carrying annular flow of air and crude oil is investigated. An experimental set-up is constructed. The test section of the experimental set-up consists of two rough pipes of galvanized iron, 8.8m long and having 2.54cm and 1.27cm ID. The DRA applied is a polyalpha-olefin (polyisobutylene). The pressure drop , Doth in the presence and the lack of DRA, has been calculated using the experimental data obtained. The results show that the addition of DRA could be effective up to certain doses of DRA, after which, the pressure drop is kept constant. A percentage drag reduction of about 45 is observed at some experimental conditions.