Cycle count for rainflow openfast

Wind & Water Computer-Aided Engineering Software Tools
1

I was looking at some of the output from openfast and noticed a pattern like bellow:

50kN 1000 cycles
203kN 337 cycles
83 kN 2000 cycles
etc
etc

i know this is part of the rainflow counting and minors rule stuff, but how does openfast determine how many cycles to run a particular load at? IE why did it choose 203kN for 337 cycles? What controls this? also how do i see all of the load history and cycle counts for each one?

thanks

2

Dear @Matt.Thomas,

OpenFAST solves the dynamic response of the wind turbine in the time domain and the response will be dictated by the turbine properties, wind/wave excitation input, and controller. Due to stochastic excitation from turbulence/irregular waves, the response typically has a range of frequency content with peak energy at natural frequencies and harmonics of the rotor speed.

Best regards,

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3

interesting. Is there a way to see the cycle counts and the associated load ?

i just want to write down a few lines of it as an example im sharing with someone

thanks

4

Dear @Matt.Thomas,

A rainflow cycle counting algorithm can be used to partition a stochastic time series into a binned set of cycle amplitudes and frequencies.

Best regards,

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