4.2.1.6. AeroDyn Theory

This theory manual is work in progress, please refer to the AeroDyn 14 manual for more details [ad-MH05]. Many changes have occured since AeroDyn 14 (e.g. BEM formulation, coordinate system used in the BEM equations, dynamic stall, dynamic BEM), but these changes are not yet documented here.

4.2.1.6.1. Steady BEM

The steady blade element momentum (BEM) equations are solved as a constrained equation, and the formulation follows the description from Ning [ad-Nin14].

4.2.1.6.2. Tower shadow models

Powles tower shadow model (TwrShadow=1) is given by:

\[u_{TwrShadow} = - \frac{C_d}{ \sqrt{\overline{r}} } \cos\left( \frac{\pi/2 \overline{y}}{\sqrt{\overline{r}}}\right)^2\]

where \(\overline{r} = \sqrt{ \overline{x}^2 + \overline{y}^2 }\).

Eames tower shadow model (TwrShadow=2) is given by:

\[u_{TwrShadow} = -\frac{C_d}{ TI \: \overline{x} \, \sqrt{2 \pi } } \exp{\left( -\frac{1}{2} \left(\frac{ \overline{y}}{ TI \: \overline{x} } \right)^2 \right) }\]

where \(TI\) is the turbulence intensity at the tower node.