Experimental evaluation of horizontal-axis marine current turbine using two scale models

Horizontal-axis marine current turbines (HAMCTs) are devices which harness kinetic energy from oceans, rivers or straits. Model scale tests are a trusted method to define the hydrodynamic characteristics of HAMCTs, and can also be used to optimise turbine design and validate numerical models.

This paper presents experimental results for model-scale 2-bladed HAMCTs with diameters of 800 mm and 500 mm, tested in a circulating water channel (CWC). Power and thrust coefficients were presented as a function of tip speed ratio at different Reynolds numbers. The effects of model scale and Reynolds number on the results were examined by comparing the experiment results between the two models. Given the tests were done in a CWC with turbulent flow; the results are lower than expected. Different hydrodynamic performance characteristics were obtained for the two scale models due to influence of model scale. The results of the 800 mm rotor are less dependent on Reynolds number for inflow speeds of 1.5 m/s and 1.7 m/s; whilst the smaller model results are affected by low Reynolds number. Having some information about the turbulence intensity of the flow during a test would lead to have a better understanding of the hydrodynamic performance of turbines.