On the design of propeller hydrokinetic turbines: the effect of the number of blades

International audience; A design study of propeller hydrokinetic turbines is explored in the present paper, where the optimized blade geometry isdetermined by the classical Glauert theory applicable to the design of axial flow turbines (hydrokinetic and wind turbines).The aim of the present study is to evaluate the optimized geometry for propeller hydrokinetic turbines, observing the effectof the number of blades in the runner design. The performance of runners with different number of blades is evaluated in aspecific low-rotational-speed operating conditions, using blade element momentum theory (BEMT) simulations, confirmedby measurements in wind tunnel experiments for small-scale turbine models. The optimum design values of the power coefficient,in the operating tip speed ratio, for two-, three- and four-blade runners are pointed out, defining the best configurationfor a propeller 10 kW hydrokinetic machine.