Clarification about yawing and `RotN`

[danrhouck]

Is there a way to yaw the turbine or set the inflow angle relative to the rotor plane? Can this be set with the geometry variable RotN, which sets the axis of rotation? I don't see a way to set RotN or anything related to yaw angle in the Matlab files provided to create geometry. I think there's more than one way to create geometry with the Matlab files, so, to be clear, I'm using create_hawt.m and editing hawt_params.m as needed for my geometry.

[whophil]

I took a quick look and it seems like yaw is best implemented by rotating the turbine's initial start geometry, but I'm not sure if yawing was ever implemented in the original Matlab geometry scripts.

[danrhouck]

OK. How do I edit the turbine’s initial start geometry? It looked to me that that’s the RotN vector and that the only way to edit it is to edit the geometry file after it’s made with the Matlab scripts.

[whophil]

You will need to modify the geometry-creating scripts to account for yaw.

[danrhouck]

For posterity, here's what I changed to build geometry for a yawed HAWT:
In CreateTurbine.m: add yaw as a new global variable. Change line 182 to require 11 inputs. Add yaw as the eleventh input in the list below. Duplicate line 236 using RotateTurbine. In the copy, replace Tilt with yaw and change the third input to [0,1,0].

In hawt_dat_to_geom.m: Add this line to the list of rotor params: yaw_angle = rotor_params.yaw_angle;. As the last input to CreateTurbine, add yaw_angle.

In hawt_params.m: Add rotor_params.yaw_angle to the list of rotor params.