windpowerlib.density.rho_ideal_gas¶

windpowerlib.density.rho_ideal_gas(pressure, pressure_height, hub_height, T_hub)[source]¶

Calculates the density of air at hub height using the ideal gas equation.

This fuction is carried out when the parameter rho_model of an instance of the Modelchain class is ‘ideal_gas’.

Parameters:	pressure (pandas.Series or array) – Pressure in Pa. pressure_height (float) – Height in m for which the parameter pressure applies. hub_height (float) – Hub height of wind turbine in m. T_hub (pandas.Series or array) – Temperature at hub height in K.
Returns:	Density of air at hub height in kg/m³.
Return type:	pandas.Series

Notes

The following equations are used [1], [2]:

$\rho_{hub}=p_{hub}/ (R_s T_{hub})$

and [3]:

$p_{hub}=\left(p/100-\left(h_{hub}-h_{p,data}\right)\cdot \frac{1}{8}\right)\cdot 100$

$R_s$ is the specific gas constant of dry air (287.058 J/(kg*K)) and $p_{hub}$ is the pressure at hub height.

References

[1]	Ahrendts J., Kabelac S.: “Das Ingenieurwissen - Technische Thermodynamik”. 34. Auflage, Springer-Verlag, 2014, p. 23

[2]	Biank, M.: “Methodology, Implementation and Validation of a Variable Scale Simulation Model for Windpower based on the Georeferenced Installation Register of Germany”. Master’s Thesis at RLI, 2014, p. 57

[3]	Deutscher Wetterdienst: http://www.dwd.de/DE/service/lexikon/begriffe/D/Druckgradient_pdf.pdf?__blob=publicationFile&v=4