Swirl Flow in Long Pipes with Different Roughness

Abstract

Swirl flow in a long pipe is experimentally investigated. In the major part of the pipe, that is, except at the entry zone with a very weak swirl, the circumferential component of the velocity is proportional to the radius near the wall. The axial component of the velocity is minimum at the center and the radial distribution is similar to the velocity profile of the wake behind a body in a uniform flow. The intensity of swirl is indicated by a parameter. The variation of the parameter and the wall pressure along the length is examined for three pipes with different relative roughnesses and semiempirical equations are derived. Using the equations, the velocity distribution and the wall pressure at any section may be predicted if the conditions at an upstream station and the relative roughness of the pipe are specified.