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Turbine data: BEM and UA |
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Turbine data: BEM and UA |
Data to control and parameterise the UA model and BEM calculation.
The model used to account for unsteady aerodynamics. If none, then the static (i.e. steady) aerofoil coefficients, as specified by the wing type coefficients, are used to determine the aerodynamic load. If Gonzalez or Minnema Pierce, the aerofoil coefficients are modified to account for unsteady effects, including dynamic stall.
You can choose whether UA is enabled for each wing type individually. By default, it will be disabled, so for the UA model to apply, UA must first be enabled for at least one wing type and the associated unsteady aerodynamics wing type data be populated.
Determines the directions, if any, in which the induction factors will be calculated, using the BEM method, and applied.
If none is selected then no induction factors are calculated and the relative flow velocity is determined purely from geometrical considerations.
If axial or axial and tangential are selected then the blade element momentum method is applied to calculate the induction factors. These factors modify the relative velocity used to determine the aerodynamic loading. Axial means that the relative velocity perpendicular to the nominal rotor plane is modified. Tangential means that the relative velocity is modified in the direction which is perpendicular to both the axial flow direction and the blade axis.
Warnings will be raised if the BEM method fails to converge, or the UA model is operating in flow conditions for which it might not be valid, provided that the simulation time exceeds the monitoring start time. If the monitoring start time is '~', then all BEM and UA warnings will be reported, regardless of simulation time. These warnings are more likely at the beginning of a simulation, when the rotor speed is low and the wind velocity is possibly being ramped up from zero. This early transient phase is often not of interest, and it is desirable to choose a monitoring start time that is sufficient to suppress BEM and UA warnings generated in this period.
A non-dimensional value which determines the accuracy to which the root of the residual function is found, when calculating the induction factors. Should you choose to increase the tolerance from the default value, we recommend that you perform sensitivity studies to confirm the accuracy of your results. If included induction is none, the BEM method is not applied and this data will not be available to edit.
Values of the non-dimensional tip speed ratio (TSR) between which the induction factors are smoothly scaled from zero to their full value. If the TSR is below the lower bound TSR, the induction factors will be set to zero; if the TSR is greater than the upper bound TSR, the induction factors are unmodified from the BEM calculation. The TSR bounds can be set to zero to supress induction scaling.
Enables the Prandtl tip loss model in the BEM calculation. If included induction is none, the BEM method is not applied and this data will not be available to edit.
Enables the Prandtl hub loss model in the BEM calculation. If included induction is none, the BEM method is not applied and this data will not be available to edit.
Enables the Pitt and Peters skewed wake model in the BEM calculation. If included induction is none, the BEM method is not applied and this data will not be available to edit.
Constant used in the skewed wake correction. If the skewed wake correction is not enabled, this data will not be available to edit. If it is '~', it is calculated as
\begin{equation} F_{s} = \frac{15 \pi}{32} \end{equation}
Enables the Øye dynamic inflow model. If included induction is none, the BEM method is not applied and this data will not be available to edit.
Parameterises the dynamic inflow model. If it is '~', the value is time dependent and calculated at each time step. If dynamic inflow is not enabled, this data will not be available to edit.