This document details how different parts of the IEA 22-MW reference wind turbine are implemented in Ashes.

1 Blade

The IEA 22-MW blade is based on the data published on GitHub in this repository: (last accessed February 2024)

1.1 Blade shape

For the Blade shape file, we used the data from the Aerodyn input file, which has the same format as Ashes. The file can be found at this link

Two modifications have been made to the Aerodyn input file:

1) The aerodyn input file uses 59 different airfoils. In order to simplify the model, we use the airfoil distribution given in the spreadsheet found at this link, in the Blade geometry tab. The model in Ashes will thus have 14 different airfoils, rather than 59.
2) The Aerodyn file gives the distance between the Pitch axis and the Aerodynamical reference point in the column BlSwpAC, whereas the Blade shape file in Ashes expects the distance between the Pitch axis and the Chordline midpoint in the PrebendInPlane column (see Blade shape file). The figrue below illustrates the difference between the two:

The red and blue text corresponds to Aerodyn and Ashes data, respectively..
AR corresponds to the location of the Aerodynamical reference point and that data was taken from the aerodyn airfoil geometry files, found on this link.
c is the chordline

From this figure, it becomes apparent that the PrebendInPlane quantity is given by
$$\text{PrebendInPlane} = \text{BlSwpAC} + c(0.5-AR)$$

Note: when computing the PrebendInPlane column, we have used the Aerodynamical reference points of the model with 59 airfoils (rather than that of the model with 14 airfoils) since those are the airfoils used to create the AeroDyn input file

1.2 Blade structure

For the Blade structure file, we use the data from the spreadsheet in the Blade structural properties. The spreadsheet gives the data as a mass and a stiffness matrix, the trabslation from that to the Ashes format is explained in the following document: Mass and stiffness matrices to Ashes format.

Note: in order to match the total mass of the blade, and since it is unclear how the distributed mass given in the spreadsheet is distributed across elements, we assign to an element in Ashes a distributed mass equal to the average between the distributed masses of the neighbouring structural stations.

2 Airfoil data

The data for the Airfoil geometry file and the Airfoil polar file for each airfoil is taken from the spreadsheet available at this link on the tabs corresponding to each airfoil.

3 Controller