Measurement of Hydroturbine Draft Tube Turbulence with Acoustic-Doppler Velocimeters

Efforts to use a multiple acoustic-Doppler velocimeter (ADV) system to measure turbulence in a hydroturbine draft tube and exit jet are reported, including an assessment of the ability of ADVs to provide useful information on the size, duration, and frequency of turbulent motions produced by hydroturbines. Such information is intended to augment traditional time-averaged and spatially averaged velocity information in future studies of hydroturbine environmental performance characteristics such as fish safe-passage and bubble evolution in auto-venting turbines. The design of the data acquisition system is presented, including ADV specifications and sampling parameters, sensing of ADV motion, high-frequency synchronization of multiple ADVs and accelerometers, and preliminary analyses of turbulent velocity time series data.