Remote acoustic measurements of turbulence in high-speed flows with application to in-stream tidal turbine development: The Vectron project

The overall goals of the project are: (I) to improve the knowledge and understanding of turbulence in high flow

tidal channels; and (II) to reduce the high uncertainty surrounding the effects of turbulence on in-stream

turbines. Specific main objectives are: (1) estimates - with error bounds - of higher-order turbulence statistics,

with an emphasis on the statistics of extremes; (2) quantitative comparisons between model-predicted

turbulence fields and measurements; (3) quantifying the turbulent contribution to Doppler noise levels in high

flow environments; and (4) improved assumptions concerning the turbulence metrics used by in-stream turbine

engineering community.

Our approach combines state-of-the-art acoustic Doppler technique with advanced computational fluid

dynamics modelling. A newly-developed acoustic Doppler system - the Vectron - will be used to make the

necessary measurements in Minas Passage in the Bay of Fundy - arguably the site with the greatest tidal power

potential worldwide. The Vectron represents a major advance in flow measurement technology, incorporating

wide-baseline convergent-beam geometry with a new pulse-coherent processing algorithm to achieve

co-located, high sampling rate, turbulence-resolving velocity measurements at or near turbine "hub height".

Turbulence-resolving Detached Eddy Simulation (DES) models employing state-of-the-art Graphical

Processing Unit (GPU) techniques will be implemented for the turbine berth area in Minas Passage, with

boundary conditions provided by a tidal circulation model encompassing the Bay of Fundy/Gulf of Maine.

The significance of the proposed research is two-fold. (1) Fundamental: The combined measurement and

modelling program will provide new knowledge, insight and understanding of turbulence in high flow tidal

channels. (2) Applied: By quantifying the recurrence frequencies of extreme velocity fluctuations in Minas

Passage, the tidal power community will have - for the first time - a reliable basis for assessing the effects of

turbulence on turbine design, performance and operational life in this and similarly challenging environments.