Experimental Study of a Small-Scale Axial Hydrokinetic Turbine with Adjustable Blade Pitch

A small-scale axial hydrokinetic turbine (HKT) with a runner having 3 blades with adjustable pitch and a diameter of 0.2 m was designed and tested to evaluate the optimum relationship between its power coefficient and its blade tip speed ratio (TSR). The design was carried out for a water velocity of 0.8 m/s and was based on the Blade Element Momentum Theory. The turbine was built by 3D printing and tested in a free surface water channel for water velocities between 0.8 and 1.1 m/s at three different blade pitch angles. The speed and torque at the turbine shaft were measured. The results of the experimental tests are encouraging and in good agreement with the literature and show that for harvesting hydrokinetic energy for power generation, fast HKTs with 3 thinner blades are more suitable than slower designs with wider blades, as the former allow a reduction in the size and cost of the electrical generator.