Autonomous Underwater Vehicles (AUVs) are increasingly important tools for marine applications. A reasonably reliable prediction of their six degrees of freedom (6DOF) motions is essential. The manoeuvrability of these unmanned submarines relies on the capability to predict the hydrodynamic forces on a freely moving submerged body. Numerical simulators integrating the full physics of the problem have been developed but their validation remains the key issue. Three-dimensional calculations still take too much computing power to complete the very large number of simulations which is required for a full validation procedure. Furthermore, a very large pool with expensive measuring devices is also necessary to obtain experimental results. It was therefore decided to construct a 2D hydrodynamic tunnel in which an object can move with three degrees of freedom solely subjected to gravity and hydrodynamic forces. In the present paper, we describe the experimental device ensuring a simple and rapid implementation of trials: a 2D channel with a constant uniform flow. A general validation is considered with an ellipse. The experimental trajectories are compared with the corresponding analytical results and discussed at the end of the paper.