Publication:
Wind turbine modeling for computational fluid dynamics
Wind turbine modeling for computational fluid dynamics
Authors
Martínez-Tossas, Luis A.
Embargoed Until
Advisor
Leonardi, Stefano
College
College of Engineering
Department
Department of Mechanical Engineering
Degree Level
M.S.
Publisher
Date
2012-05
Abstract
With the shortage of fossil fuel and the increasing environmental awareness,
wind energy is becoming more and more important. As the market for wind
energy grows, wind turbines and wind farms are becoming larger. Current
utility-scale turbines extend a signi cant distance into the atmospheric boundary
layer. Therefore, the interaction between the atmospheric boundary layer and the
turbines and their wakes needs to be better understood. The turbulent wakes of
upstream turbines affect the flow field of the turbines behind them, decreasing
power production and increasing mechanical loading. With a better understanding
of this type of flow, wind farm developers could plan better-performing, less
maintenance-intensive wind farms. Simulating this flow using computational fluid
dynamics is one important way to gain a better understanding of wind farm flows.
In this study, we compare the performance of actuator disc and actuator line models
in producing wind turbine wakes and the wake-turbine interaction between multiple
turbines. We also examine parameters that a ect the performance of these models,
such as grid resolution, the use of a tip-loss correction, and the way in which the turbine force is projected onto the flow field. We see that as the grid is coarsened,
the predicted power decreases. As the width of the Gaussian body force projection
function is increased, the predicted power is increased. The actuator disk and
actuator line models produce similar wake profiles and predict power within 1%
of one another when subject to uniform in flow. The actuator line model is able
to capture flow structures near the blades such as root and tip vortices, which the
actuator disk does not capture, but in the far wake, they look very similar. The
actuator line model was validated using the wind tunnel experiment conducted in
The Norwegian University of Science and Technology, Trondheim. Good agreement
between the model and the experiments was obtained, with maximum percentage
difference in power coefficients of 25% and 40% for thrust coefficient. The actuator
line and actuator disk models were compared when running large-scale wind farm
simulations. Normalized power was very similar for both models but dimensional
power was within 1 and 17% difference from of each other. The actuator disk
model was able to run roughly 3 times faster though. This work shows that
actuator models for wind turbine aerodynamics are a viable alternative to fully
blade resolving simulations. However, care must be taken to use the proper grid
resolution and force projection to the CFD grid to obtain accurate predictions of
aerodynamic forces and hence power. More work needs to be done to determine the
best method of body force projection onto the CFD grid.
Keywords
Computational fluid dynamics
Usage Rights
Persistent URL
Cite
Martínez-Tossas, L. A. (2012). Wind turbine modeling for computational fluid dynamics [Thesis]. Retrieved from https://hdl.handle.net/20.500.11801/414