TurbSim User's Guide: Version 1.06.00 - NREL

Figure 8. Coherent turbulent kinetic energy (CTKE) of an example simulation using KHTEST: thecoherent structure placement in the middle of the time series is shown by the red linesIEC_WindType: IEC Turbulence Model [-]This parameter indicates which IEC wind model will be used. Valid entries, which are found inTable 5, include the Normal Turbulence Model (NTM), Extreme Turbulence Model (ETM), andExtreme Wind Speed Model (EWM) using the 10-minute average wind speed with a recurrenceperiod of 1 year or 50 years. Note that the EWM scaling parameters in TurbSim are valid onlyfor 10-minute simulations. The definitions of these models and of the wind turbine classes can befound in the IEC 61400-1 standard (3 rd ed.) [20]. If the IECturbc parameter was specified as apercentage instead of as a standard turbulence category, the wind model must be “NTM.” Thisinput is used only with the IEC spectral models.ETMc: Extreme Turbulence Model Parameter c [m/s]The ETMc input parameter is the value of the variable c in the equation for the longitudinalcomponent standard deviation, σ1, in the ETM (see Eq. 19 in section 6.3.2.3 of IEC 61400-1 3 rded. [20]):⎛⎛Vave⎞ u⎞hubσ1 = cI ⎜ref0.072 3 ⎛ 4 ⎞⎜ + − + 10⎟c⎟ . (8)⎜ ⎝ ⎠ ⎜ c ⎟ ⎟⎝⎝ ⎠ ⎠Table 5. Valid IEC Turbulence ModelsIEC_WindTypeNTM1ETM2ETM3ETM1EWM12EWM13EWM11EWM502EWM503EWM50DescriptionNormal Turbulence ModelClass I Extreme Turbulence ModelClass II Extreme Turbulence ModelClass III Extreme Turbulence ModelClass I turbulent Extreme Wind Speed Model, 1-yr recurrenceClass II turbulent Extreme Wind Speed Model, 1-yr recurrenceClass III turbulent Extreme Wind Speed Model, 1-yr recurrenceClass I turbulent Extreme Wind Speed Model, 50-yr recurrenceClass II turbulent Extreme Wind Speed Model, 50-yr recurrenceClass III turbulent Extreme Wind Speed Model, 50-yr recurrence14