Are Nearly all Tidal Stream Turbines Designs Wrong for the Pentland Firth? Stephen Salter Institute for Energy Systems University of Edinburgh

No names, no pack drill.

Edinburgh vertical-axis, variable-pitch with rim power take off. EWTEC Patras 1998

... just like wind turbines but under water. Frederick Lanchester Albert Betz

BUT for a turbine in a duct:

Open flow field Duct

No names, no pack drill.

Ross McAdam

McAdam RA, Houlsby GT, Oldfield MLG. Experimental measurements of the hydrodynamic performance and structural loading of the transverse horizontal axis water turbine: part 1. Renewable Energy vol. 59 pp

Edinburgh vertical-axis, variable-pitch with rim power take off. EWTEC Patras 1998

Cam circumference628 m Cam rise120 mm Cam wavelength970 mm Lobe number 653 x Bogie length600 mm Coach number60 Stations per coach16 Rollers per station8 Roller number60 x 16 x 8 = 7680 Roller force10 E5 N Cycles per rotation2612 x 7680 = 20 million Power

No tip-to-hub velocity reduction No squeezing torque through a bearing. On-line shirt-sleeve access at the surface. Thousands of force lines. Contact-free gutter seal. Lots of space.

GOOGLE IMAGES MoD order the stretcher bearers to be at the same end ?

Flow Impedance The determination of the water to flow despite the introduction of obstacles.

Flow Impedance The determination of the water to flow despite the introduction of obstacles. Ratio of head increase to flow-rate reduction.

Flow Impedance The determination of the water to flow despite the introduction of obstacles. Ratio of head increase to flow-rate reduction.

Flow Impedance The determination of the water to flow despite the introduction of obstacles. Ratio of head increase to flow-rate reduction.

Flow Impedance The determination of the water to flow despite the introduction of obstacles. Ratio of head increase to flow-rate reduction.

Flow Impedance The determination of the water to flow despite the introduction of obstacles. Ratio of head increase to flow-rate reduction.

Tidal turbine array optimisation using the adjoint approach. S.W.Funke P.E.Farrell M.D.Piggott Renewable Energy 2013

Tidal turbine array optimisation using the adjoint approach. S.W.Funke P.E.Farrell M.D.Piggott Renewable Energy 2013

Laminaria Hyperborea (kelp) are found along the edges of the Pentland Firth at depths up to 30 m. Length can reach 3.5 metres. Cf = ?

Pentland bed stills. P Hayes. Fisheries Research Aberdeen mm bob

Baston and Harris

Abbot I H and von Doenhoff AE Theory of Wing Sections NACA

Friction coefficients for Fshear = 0.5 ρ U 2 Cf TW x 0.04 = 247 GW

Are Nearly all Tidal Stream Turbines Designs Wrong for the Pentland Firth? Stephen Salter Institute for Energy Systems University of Edinburgh