Approximation function for betz coefficient based on six parameters (see Heier2009, page 39)
function betzCoefficient extends TransiEnt.Basics.Icons.Function; input TransiEnt.Producer.Electrical.Wind.Characteristics.VariableSpeed.BetzCoefficientApproximation param "Coefficients for approximation (turbine characteristic)" annotation( choicesAllMatching = true); input Real lambda "Tip speed ratio"; input Real beta "Pitch angle"; output Real cp "Betz factor"; end betzCoefficient;