TurbSim: Wind variable HFlowAng

Hi,

do you know how can I generate a wind file with different HFlowAng without using random turbulence models.
I would like to generate a wind field where the horizontal cross flow varies e.g. between -20 deg and 10 deg during 600s and no turbulence.
is this possible?

thanks!

Best Regards
Pablo Guarnizo

Dear Pablo,

If you wish to generate wind without turbulence, use AeroDyn’s simple “hub-height” format wind data file in place of wind files generated by TurbSim.

Best regards,

Hi Jason,

thank you very much for your support, it worked I could generate a wind file with changing cross-wind vWind and no turbulence.
But I realize that FAST provides different results depending which format is selected for the input wind file i.e. bts or hh. even when the input wind is exactly the same.
I guest the inflow model used for the wind turbine in the simulation is different.

my question now is:

is it possible to generate a wind file with turbsim where the HFlowAng (cross wind vWind) changes i.e. HFlowAng gets different values in the same wind file.
what would be the best way to make it?

Tank you very much in advance!

Best regards
Pablo

Pablo,

My guess is that the differences you see in the FAST results using HH vs FF wind files representing the same flow field is because of the way AeroDyn calculates the “average disk velocity.” I have never liked the implementation AeroDyn uses, which takes

  • the instantaneous wind speed and direction (not including gust speeds or any shear) from the HH files to calculate a sort of disk-averaged wind speed, or
  • the FF advection speed for the U component, and 0 for the V and W components, which is the time-averaged hub-height wind speed (assuming the FF file has no wind direction)

So, it uses different averaging methods based on the type of wind file being used, and it can give very different results.

TurbSim does not have the ability to have time-varying HFlowAng. You could try to generate your own FF binary file to be read in AeroDyn/InflowWind, using formats/code descirbed in this post: http://forums.nrel.gov/t/running-fast-based-on-cfd-turbulence-fields/774/1.