River Test

The SST concept was successfully tested in 2001 - 2 on a 1.5m diameter model in the Thames at Chiswick. This test established that the buoyancy support concept works well, and can be controlled to successfully present the turbine in its installation, operational and maintenance positions. It also demonstrated that the stall-regulated rotor runs stably on a flexible trailing arm and extracts power from the stream (see image below).

The 1.5m diameter Thames test turbine running in a 0.8 m/s flood tide (water flowing top to bottom). Note the upstream bow-wave as the water tries to go around the rotor.

Computer-generated image of the test set-up at Chiswick Pier - ebb tide, water flow left to right.

Actual set-up for the river test. Buoyancy tanks on the model are proportionately large because of square-cube scaling effect. Gearbox - generator can be seen behind the (three-bladed) rotor. On the right is the hinged support frame.

Float-out of the 1.5m diameter test turbine (aluminium soft buoyancy tank on the left full of air; fixed buoyancy sail on the right). The 'seabed' balljoint connector can be seen in the foreground.

The 'seabed' connection is made (view now from above) and the turbine goes nicely into its 'maintenance' position.

The buoyancy tanks are flooded and the turbine begins to roll over towards its operating position....

... and over ....

... and over ....

... and into its operating position. The rotor is about 20 cm below the water, which is on the ebb tide (right to left).

The rotor running and extracting power in a 0.8 m/s flood tide (top to bottom). Notice the head of water upstream of the rotor as the water tries to avoid going through it and giving up its energy. A sobering thought that the tidal flow in the Pentland Firth can reach 16 knots (8 m/s) - ten times the flow here in the Thames!