Experimental Study of Roughness Influence on a Turbulent Pipe Flow

The main goal of this study is to obtain experimental data to develop adapted hydraulic and thermal wall functions used by industrial CFD codes. An experimental study, based on a test rig designed to reproduce realistic flow characteristics, has been conducted in order to explore velocity and temperature profiles. Hydraulic characterization of turbulent pipe flow was conducted over a Reynolds number range of 20 000 to 90 000, with three different test sections, presenting an increasing sand grain roughness. The three components of the flow velocity were measured, using laser Doppler velocimetry, and particle image velocimetry. The results obtained give access to turbulent quantities, to non-dimensional velocity profiles and to velocity defect in the boundary layer. These results are considered sufficient to cover the hydraulic requirements of an adequate wall-function related to surface roughness.