The water tunnel provides a means to visualize the flow around complex shapes either through the injection of coloured dyes at points on the surface of the model or by tracing the water with small particles or electrolytically-generated hydrogen bubbles. It is also used to perform PIV, PTV or LDV non-intrusive optical measurements of instantaneous or average velocity fields and turbulent structures. The WT-1 is a continuous facility featuring a pump with a maximum head and flow rate of 18 m and 21.6 m3/h, but can also be run in the blow-down mode when ultimate flow quality is required.
The settling chamber, where a constant water level is controlled by an overflow weir, is fitted with two layers of open-cell polyurethane foam and an anodized aluminum honeycomb. The water volume flow is measured by four rotameters, with ranges from 1000 to 16 m3/h. The fairly long (900 mm) test section is completely built out of transparent plexiglass with a cross section of 120 mm x 240 mm to provide flow speeds up to 0.15 m/s. The test section is fitted with interchangeable plexiglass doors on which all model supports and portholes are fixed, to preserve integrity of the other walls and full optical access through them.