Actuator disk theory and blade element momentum theory for the force-driven turbine

The Actuator Disk Theory and the Blade Element Momentum Theory (BEMT) are widely applied in the field of tidal and wind turbine design. The current BEMT turbine design method is based on the assumption of achieving the Betz limit when the axial induction factor (a) reaches 13. But this only applies to turbines driving by a constant velocity, i.e. the velocity-driven turbine. This paper introduces a new type of turbine, namely the force-driven turbine which by its name is driven by a constant force.This paper then expanded the actuator disk theory for the force-driven turbine and identified the relationship between the axial induction factor with the power and the energy yield of the force-driven turbine. According to the relationship, this paper proposes a new BEMT turbine design method for the preliminary design of the forcedriven turbine. Then, a case study is conducted to demonstrate and verify the developed method. The case study shows the newly developed method can be used to quickly and effectively identify the optimum design for forcedriven turbines.