The power system based on the horizontal axis turbines has been extensively employed to harness the kinetic energy of the moving fluid to generate the clean renewable energy in several domains, such as wind, river, and sea. The characteristic of the rotational speed is one of the prominent aspects in designing the power based on the horizontal axis turbine. This is the characteristic that can determine the quantity of the electricity production in the generator on the power technology system.

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... e number of blades is another important aspect in designing the technology. It is believed that the number of blades not only determines the aerodynamic performance, the construction, and the production cost but also the turbine rotational speed characteristics. This study investigates the effect of the blade number on the rotational speed characteristic of a horizontal axis river current turbine. The methodology of generating the investigation is a parametric study using the blade element momentum theory. The result shows that the turbines with low blade number have high rotational speed characteristics while the turbines with high blade number have low rotational speed characteristics. The very low attack angle which yields into a low lift coefficient is one of the factors responsible for the inability of the turbines with high blade number to operate at high rotation. A further discussion on the results on this investigation relating to the hydrodynamic behavior is explored in this study. It is recommended that when a turbine is decided to have a high blade number, the transmission ratio should be high to obtain a high rotation in the generator.