Flow characteristics in low-speed wind tunnel contractions: Simulation and testing

A numerical and experimental study was conducted to characterize flow through low-speed wind tunnel contractions. The simulations were carried out using an incompressible, two-dimensional flow solver based on finite volume scheme, predicting flow along the core, and at immediate vicinity of the wall of three pre-selected wall-shape contractions. The numerical results have been validated against experimental data obtained, utilizing laser-Doppler anemometer (LDA). Particular attentions have been given to the bulk flow velocity, the centerline mean velocity, the centerline velocity fluctuations, the uniformity of the mean velocity distribution at contraction's exit, and to the mean pressure coefficient. The experimentally determined mean-pressure coefficient values along the centerline and at contraction exit were found to be similar to those predicted numerically. The fifth-order polynomial contraction showed, however, good flow characteristics at the exit plane with small non-uniformity when compared to both the two-cubic arcs and the Witoszynski second-order polynomial contractions. It was therefore adopted for the Cottbus Large pipe (CoLaPipe) facility at the Department of Aerodynamics and Fluid Mechanics (LAS), BTU-Cottbus-Sefftenberg. (C) 2017 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).