Unusual approach to tunnel testing of blades by NEMMO project
A scale model of a tidal turbine is being tested in SSPA’s cavitation tunnel, in order to verify the efficiency of the blades and provide data for improved blade design.
The tests measure thrust and torque, while varying the rotational speed of the blades with an electrical motor. Blade pitch angles within a range of 12-18 degrees are tested across a range of rotational speeds. 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 model is at 1:38 scale, with blade diameters of 50cm, and the tests emulate the full-scale advance ratio with a constant flow speed of 2.5m/s. The next tests will include LDV (Laser Doppler Velocimetry) measurements for use at assessing the efficiency of the downstream blade and further CFD validation.
Check out the short video of the turbine being tested: