NEMMO spins angled turbine blades

A scale model of a tidal turbine is being tested in SSPA’s cavitation tunnel in Sweden as part of the NEMMO research project.

Scaled tidal turbine being tested at SSPA (Courtesy of NEMMO)

The tests measure thrust and torque, while varying the rotational speed of the blades with an electrical motor, in order to verify the efficiency of the blades and provide data for improved blade design.

Blade pitch angles, within a range of 12-18 degrees, are tested across a range of rotational speeds, according to the researchers.

As this turbine is designed to operate at oblique current angles, the entire model is rotated horizontally to simulate the current at angles of attack between 0-20 degrees, which is a quite unusual feature to test in cavitation tunnels, the project developers said.

The model tested is at 1:38 scale, with blade diameters of 50 centimetres, and the tests emulate the full-scale advance ratio with a constant flow speed of 2.5 m/s.

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The next tests will include LDV (Laser Doppler Velocimetry) measurements for use at assessing the efficiency of the downstream blade and further CFD validation.

The Next Evolution in Materials and Models for Ocean Energy (NEMMO) project is expected to boost the competitiveness of tidal energy by optimising tidal turbine blade design and performance.

NEMMO aims to create a larger, lighter, and more durable composite blade for floating tidal turbines, enabling devices to reach capacities of over 2 MW.

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The project is being developed by twelve international partners including ADERA, Blaest, Dublin City University, Funditec, INPRE, ITAINNOVA, Magallanes Renovables , SPNano, SSPA, Ocean Energy Europe, Technion, and Tecnalia.