windpowerlib.density.barometric¶
-
windpowerlib.density.
barometric
(pressure, pressure_height, hub_height, temperature_hub_height)[source]¶ Calculates the density of air at hub height using the barometric height equation.
This function is carried out when the parameter density_model of an instance of the
ModelChain
class is ‘barometric’.Parameters: - pressure (pandas.Series or numpy.array) – Air 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.
- temperature_hub_height (pandas.Series or numpy.array) – Air temperature at hub height in K.
Returns: Density of air at hub height in kg/m³. Returns a pandas.Series if one of the input parameters is a pandas.Series.
Return type: pandas.Series or numpy.array
Notes
The following equation is used [1], [2] :
- with:
- T: temperature [K], h: height [m], : density [kg/m³], p: pressure [Pa]
is the height of the measurement or model data for pressure, the ambient air pressure, the ambient density of air, the ambient temperature and the temperature at hub height .
Assumptions:
- Pressure gradient of -1/8 hPa/m
References
[1] Hau, E.: “Windkraftanlagen - Grundlagen, Technik, Einsatz, Wirtschaftlichkeit”. 4. Auflage, Springer-Verlag, 2008, p. 560 [2] Deutscher Wetterdienst: http://www.dwd.de/DE/service/lexikon/begriffe/D/Druckgradient_pdf.pdf?__blob=publicationFile&v=4