On the design and testing of a research device about streaming water phenomena

The Group of Mechanical Design of the University of Brescia was charged with the task to develop, and design a large scale facility aimed to perform tests about streaming water phenomena, the final user being the Group of Civil Hydraulics of the same University. The facility has been designed, developed and successfully tested. It is mainly composed with a sub-horizontal channel, flat bottomed and transparent walled. The cross area of the streaming flow can be reduced and the slope can be controlled (0 to 7°). Very severe requirements were foreseen with respect to smoothness and planarity (0.5 mm Vs 12 m length and 700 mm width). Acceptable deformations were limited to very slight values, although the length of the channel being remarkable and the expected loads being widely variable, due to the relevant range of foreseen speeds and flow rates of streaming water (sand and small stones transport by stream had been foreseen too). To guarantee the required flatness along the whole channel a modular design has been adopted and proper means to adjust the fitting between contiguous modules have been developed. Notice the sealing must not be compromised in adjusting phase. A mobile support free to be moved along the channel has been designed in order to allocate a number of measuring probes devoted to hydraulic phenomena monitoring. An inlet tank was designed too, equipped with proper devices to guarantee a smooth and waveless inlet of water in the whole range of foreseen flow rates (up to 220 litres/s). An output tank was equipped with proper piping and pumping items to re-circulate the fallen water. Of course devices to precisely modify the slope rate were developed too. The facility has been installed and is nowadays in use for scientific and teaching purposes. In the proposed paper the following items will be dealt with: exact design requirements definition, study and design phases, solid modelling of the plant, building, trials and delivery, some considerations about using geometric and dimensional tolerancing (GD&T) on machine with relevant measures.