About¶
TurbSim is a statistical rather than a physical or dynamic tool. That is, rather than solving fluid-flow equations (e.g. large eddy simulations) it produces time-series that match specific statistics of real flows. PyTurbSim is capable of matching the following statistics of any velocity dataset:
- the mean velocity profile,
- the turbulent kinetic energy spectrum (and therefore the turbulence intensity),
- the Reynold’s stress profile, and
- the spatial coherence.
These statistics have been found to be critical predictors of wind-turbine fatigue loading. Therefore, though this tool does not produce time-series that obey fluid-flow equations (i.e. the Navier-Stokes equations, compressibility), it does provide time-series that drive realistic wind and MHK turbine device simulation and it does so using significantly lower computational resources than fluid-flow simulations. That is, TurbSim and PyTurbSim efficiently produce time-series that drive realistic loads estimates that agree reasonably with measurements of loads on real wind turbines [1].
History¶
pyTurbSim is a python-implementation of the National Wind Technology Center’s (NWTC) ‘TurbSim’ program [2]. Throughout the documentation, the term ‘TurbSim’ is used to refer to both PyTurbSim and the original TurbSim tool (hereafter ‘O-TurbSim’). O-TurbSim is still actively maintained and available from the NWTC design codes site.
PyTurbSim was originally written as a script for developing and testing new profile and turbulence models that would later be incorporated into O-TurbSim. The idea was that the script could be quickly modified and executed to produce new output that could be compared to measured datasets (for validating new models) or O-TurbSim output (for validating the script). Once a new model had been developed it could then be incorporated into O-TurbSim and released as part of O-TurbSim. As the ‘PyTurbSim script’ was developed to simplify its use it became a full-fledged program of its own with some capabilities that exceed O-TurbSim. O-TurbSim has capabilities that are not included in PyTurbSim as well; see the capabilities.txt file for a comparison of capabilities of these two tools.
PyTurbSim does supports some, but not all spectral models of the original (atmospheric) TurbSim program. Furthermore, PyTurbSim does not support the ‘coherent structures’ functionality that Neil Kelley developed. For producing simulations of atmospheric turbulence, I highly recommend using the original TurbSim program, developed by Bonnie Jonkman and Neil Kelley (based on the original SNLWIND tool developed by Paul Veers). That having been said, I believe the ‘SMOOTH’ and ‘IEC’ spectral models are accurately represented by this tool. All other spectral models have not been verified or are not included in this tool. PyTurbSim would not be possible without the work of Niel Kelley, Paul Veers and especially Bonnie Jonkman. Thank you to all of these people for their excellent work and support in creating this tool.
The PyTurbSim documentation is based on O-TurbSim’s documentation. For additional information, especially regarding the ‘config’/’input’ file operational mode, take a look at that document.
License¶
PyTurbSim is released publically by the National Renewable Energy Lab under the FreeBSD license (see the COPYRIGHT file in the repository).
| [1] | Moriarty, P. J.; Holley, W. E. & Butterfield, S. Effect of turbulence variation on extreme loads prediction for wind turbines Transactions of the American Society of Mechanical Engineers Journal of Solar Energy Engineering, AMERICAN SOCIETY MECHANICAL ENGINEERS, 2002, 124, 387-395 |
| [2] | The NWTC is a center at the Department of Energy’s (DOE) National Renewable Energy Lab (NREL). The DOE provided funding for development of these tools. |