In the present study, a systematic experimental investigation on the effect of a circular disk obstacle placed axi-symmetrically in the line of a vertical helium jet is presented. The obstacle is placed within the 2 m(3) enclosure of AIHMS facility. The location of the obstacle and volume Richardson number have been varied parametrically and the results are compared with those of the free jet with obstacle. The experimental data shows that the obstacle enhances mixing near the obstacle, decreases transport of helium to upper regions of the enclosure and increases transport to lower regions of the enclosure. This effect decreases with increase in the distance between the obstacle and the jet exit. The effect is more pronounced at higher jet velocities i.e. at lower values of volume Richardson number. The experimental database presented can be used for validation of CFD models, grid independence studies, and gaining user experiences before complex problems on helium hydrogen distribution in confined spaces are taken up. (C) 2018 Elsevier Ltd. All rights reserved.