Inlet region flow with polymer additives

Drag reduction due to polymer injection in the inlet region and the fully developed flow region of a pipe, and the general characteristics of mean flow in the developing axisymmetric turbulent boundary layer for the inlet region of a pipe, were experimentally investigated. Experiments were conducted in a 12-in. diameter 200 ft long commercial steel pipe. Poly (ethylene oxide), commercially known as Polyox WSR 301, was injected circumferentially through a perforated injector at 3.5 diameters from the pipe entrance. Drag reduction in the inlet region was found to be a function of Reynolds number, polymer mass flow rate and distance from the injector, but was not significantly dependent on injection concentration or injection velocity. Maximum drag reduction values in excess of 90 percent were recorded in the inlet region. The location of maximum drag reduction occurred between 5 and 11 diameters downstream of the injector.