Design, commissioning and performance of a device to vary the turbulence in a recirculating flume

Ambient turbulent flow structures are one of the key drivers that will determine the rate of wake recovery downstream of tidal turbines. For second and third generation arrays or farms such a parameter is critical for the determination of inter-device spacing and the optimisation of energy extraction per unit surface area. At present offshore flow characterisation is dominated by seabed or surface-mounted diverging-beam acoustic Doppler profilers that whilst having a good spatial capture cannot characterise turbulent flow structures to the same accuracy as single point converging laboratory-scale velocimeters. So a paradox presently exists: We can measure the (mean) flow characteristics at real tidal energy sites but lack the ability to accuracy ascertain high-frequency flow characteristic at discrete spatial locations. This is possible at laboratory-scale with convergent-beam devices but as we do not know the real site conditions replication at small-scale can only