Blade Section Geometry

The blade geometry is defined for each blade station. Select the option at the bottom of the screen to specify either the distance along blade or distance along blade root Z-axis. The alternate value will be automatically calculated using the neutral axis values. For example, selecting Distance along blade will automatically calculate the Distance along blade root Z-axis, and vice versa. For details refer to the section on Distance Along Blade. The following geometry data is required at each blade station:

Table 1: Overview over required geometry parameters for blade definition in Bladed

Variable identifier	Unit	Description
Distance along blade	\(\bunit{m}\)	The distance from the blade root to the current station along the neutral axis, which may not be straight. It must be zero for the first station.
Distance along blade root Z-axis	\(\bunit{m}\)	The distance of the blade station along the blade root Z-axis.
Chord	\(\bunit{m}\)	The distance from the leading edge to the trailing edge along the chord line.
Aerodynamic twist	\(\bunit{deg}\)	The local angle of the chord line. More positive values of twist and set angle push the leading edge further upwind in the direction from which the flow is coming.
Thickness	\(\bunit{\%}\)	The thickness of the blade as a percentage of the chord at that station.
Neutral axis (x)	\(\bunit{m}\)	The distance from the blade root Z-axis to the neutral axis in the x-direction. This would be non-zero if, for example, the blade was pre-bent.
Neutral axis (y)	\(\bunit{m}\)	The distance from the blade root Z-axis to the neutral axis in the y-direction.
Elastic centre (x')	\(\bunit{\%}\)	The distance from the leading edge to the elastic centre along the chord x-axis, as a percentage of the chord.
Elastic centre (y')	\(\bunit{\%}\)	The distance from the leading edge to the elastic centre along the chord y-axis, as a percentage of the chord.
Foil section	\(\bunit{-}\)	An index number defining the aerofoil section at that station.
Moving/Fixed	\(\bunit{-}\)	Differentiates between fixed and movable parts of the blade for aerodynamic regulation or braking, either by bodily changing the pitch of that part of the blade, or by deploying an aileron, flap or other aerodynamic control surfaces.

Figure 1 and Figure 2 illustrate a blade station for Clockwise and Anticlockwise rotor configurations. It is assumed that the perspective is from the tip toward the root, aligned to the root axes plane.

Figure 1: Aerofoil at a blade station illustrating root axes, principal elastic axes and chord axes.

Anticlockwise Rotors

The blade inputs for an Anticlockwise rotor use a left-handed coordinate system, in contrast to the right-handed system for Clockwise rotors. As a result, no changes are needed to the input data when switching between Clockwise and Anticlockwise rotors. See Figure 2 for an illustration of the Anticlockwise blade definition.

Figure 2: Anticlockwise rotating blade station, where the left-handed coordinate system ensures compatibility when switching between rotor directions.

Last updated 13-12-2024