Verifying the Blade Element Momentum Method in unsteady, radially varied, axisymmetric loading using a vortex ring model.

Although the Blade Element Momentum method has been derived for the steady conditions, it is used for unsteady conditions by using corrections of engineering dynamic inflow models. Its applicability in these cases is not yet fully verified. In this paper, the validity of the assumptions of quasi-steady state and annuli independence of the blade...

The wake of an unsteady actuator disc

Blade Element Momentum (BEM) is the most important aerodynamic analysis method for wind turbines. BEM is derived assuming stationary conditions, which limits its ability to model the unsteady aerodynamic effects. This becomes increasingly relevant for the flexible blades of current large-scale turbines, and the employment of passive and active...

New dynamic-inflow engineering models based on linear and nonlinear actuator disc vortex models

Two new engineering models are presented for the aerodynamic induction of a wind turbine under dynamic thrust. The models are developed using the differential form of Duhamel integrals of indicial responses of actuator disc type vortex models. The time constants of the indicial functions are obtained by the indicial responses of a linear and...