Low-Computational-Cost Parabolic RANS Solver for Simulating and Optimizing Wind Turbine Columns




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A computational fluid dynamics tool for prediction of wakes and their interactions within a wind turbine column is presented. A Reynolds-averaged Navier-Stokes (RANS) solver is developed for axisymmetric wake flows using parabolic and boundary-layer approximations, in order to achieve a good trade-off between computational cost and accuracy, with the aim of application in optimization problems of wind farms. Boussinesq hypothesis and a length scale varying as a function of the streamwise location, calibrated from higher accuracy large eddy simulation (LES) dataset, are modeled through a mixing length model and a parabolic transport equation of the turbulent kinetic energy. The novelty of this work consists in modeling the mixing length to accurately predict time-averaged velocity field in the presence of wake interactions as well as varying incoming free-stream turbulence. The actuator disc model is implemented in the parabolic scheme for simulating turbine effects and estimating power production. The RANS simulations have a good agreement with the LES dataset in comparing the wake field, time-averaged turbulence statistics and power production, for cases designed to test effects of tip speed ratio, spacing between turbines and free-stream turbulence. Furthermore, the RANS solver is also assessed with good agreement with wind tunnel experiments of a turbine model. The tool is then leveraged in optimization problems considering different algorithms and objective functions. The proposed Parabolic RANS (P-RANS) solver is a great alternative for analytical and engineering wake models in obtaining more accurate predictions while requiring two orders of magnitude lesser computation than LES.



Wind turbines—Aerodynamics, Wakes (Aerodynamics), Actuators, Computational fluid dynamics, Wind power plants, Dynamic programming, Structural optimization



©2017 Vignesh Santhanagopalan. All rights reserved.