FAST/AeroDyn Time Shift When Using FF Wind Files

Wind & Water Computer-Aided Engineering Software Tools
1

Hi all,

I’m using FASTv7 through Simulink for a simulation with a full-field wind file. I am looking at the uWind output from FAST and the grid point that correspond to the hub-height point in the human readable form of the FF wind file (.u). In my case there is a time-shift between these two signals that is greater than 1.5 seconds. This is a behavior I haven’t seen with .hh wind files. Is there a way of calculating this time-shift without running a simulation? Also, is there a simple explanation of this behavior?

Thanks!
Arda

2

The current implemetation of AeroDyn/InflowWind shifts the full-field files by the distance of GridWidth/2 meters, so the time difference you will see between the FF and HH files is GridWidth/(2*UHub) seconds. This is described in the TurbSim User’s Guide; see Figure 17 (page 28) and the section on “UsableTime” (pages 9-10).

3

Hi Bonnie,
Thank you very much for your answer!
Arda