Abstract
New tidal flow measurements have been obtained upstream of the Meygen Phase 1A turbines from recent bed mounted acoustic doppler current profiler deployments. This paper presents a preliminary assessment of the flow speed and direction, streamwise turbulence intensity and wave climate at two of the turbine locations. Flow speeds and directions are strongly influenced by proximity to Stroma, which diverts the flow into the Inner Sound, resulting in higher speeds and available energy at the north of the site. Comparisons of the average flood and ebb flow directions at each of the turbine locations show differences of 10_. Streamwise turbulence intensities were found to be greatest during ebb tides at the two study locations. Initial results suggest that this is caused by both bed and wave generated turbulence. Large roughness features located to the east (ebb side) of the turbines are the likely cause of eddy shedding and increased shear in the outer flow. Wave measurements show that wave height and zero up crossing period were greatest during ebb tides when wave propagation opposes the flow direction. Preliminary power curve testing shows that the average coefficient of power of the Meygen Phase 1A turbines is 0.41, which exceeds their contractual requirement by 8%. Preliminary results indicate that the turbines are performing well in response to the different turbulent onset flows observed at the Meygen site.