Users may receive a number of warnings when running Bladed simulations such as following:
*** WARNING: Cannot find relevant gradients within polar range for Foil data set 23 to apply the linear fit method. Slope is set to: 6.28319.
*** WARNING: Cannot find relevant gradients within polar range for Foil data set 22 to apply the linear fit method. Slope is set to: 6.28319.
*** WARNING: Cannot find relevant gradients within polar range for Foil data set 23 to apply the linear fit method. Slope is set to: 6.28319.
*** WARNING: Cannot find relevant gradients within polar range for Foil data set 22 to apply the linear fit method. Slope is set to: 6.28319.
Bladed versions affected: all Bladed versions supporting Linear Fit Gradient method.
Date of last article update: 12 December 2022
These warning messages are completely fine and safe. This indicates that the polar data at the specific section number provided in the message has a gradient that is outside [+1.8*pi,+2.5*pi] range when it is searched using the linear fit gradient method (see Linear Fit Gradient Method). Therefore a value of 2*pi (more precisely around 6.28318530718) is adopted for the dynamic stall calculations if being defined.