The design, construction, and validation of a new academic wind tunnel is described in detail. The wind tunnel is of a classical, blow-down type and generates a pressure-induced, turbulent separation bubble on a flat test surface by a combination of adverse and favorable pressure gradients. The Reynolds number, based on momentum thickness just upstream of separation, is Re θ  5,000 at a free-stream velocity of U ref = 25ms -1 . The length of the separation bubble is estimated at 0·42 ± 0·02m by three different methods. Results of a numerical simulation demonstrate the absence of flow separation in the wind-tunnel contraction. This results in a turbulence level of about 0·05% in the test section. Oil-film visualisation experiments show that the flow near the wall is strongly three-dimensional in the recirculating region and that the topology of the limiting streamlines is consistent with experiments performed on configurations with fixed separation. Finally, spatial variations of the forward-flow fraction have been documented using a thermal-tuft probe and are shown to compare well with the results of the oil-film visualisation.

The design, construction, and validation of a new academic wind tunnel is described in detail. The wind tunnel is of a classical, blow-down type and generates a pressure-driven, turbulent separation bubble on a flat test surface. The Reynolds number, based on momentum thickness just upstream of separation, is Re θ 5000 at a free-stream velocity of U ref = 25 m/s. The length of the separation bubble has been estimated at 0.42 ± 0.02 m by three different methods. Experimental and numerical results demonstrate the absence of flow separation in the wind-tunnel contraction. This results in a turbulence level of about 0.05% in the test section. Oil-film visualization experiments show that the flow near the wall is strongly three-dimensional in the recirculating region and that the topology of the limiting streamlines is consistent with experiments performed on configurations with fixed separation. Finally, spatial variations of the forward-flow fraction have been documented using a thermal-tuft probe and are shown to compare well with the results of the oil-film visualization.