EnginSoft International Conference 2010 |
Full 3D CFD Optimization of Horizontal Axis Wind Turbine |
De Bellis Fabio - Politecnico di Bari (Italy) |
Abstract |
The study and the development of Horizontal Axis Wind Turbines (HAWTs) involve problematic fluidynamic features: stall, three dimensional secondary flows and rotational effects. At the same time, the call for more efficient wind turbines is continuously growing. Due to the complexity of the flow around the blades however, HAWT optimization is commonly based on BEM techniques or similar, which are able of predicting wind turbine performance with much less computational resources than Computational Fluid Dynamics (CFD). The drawback of this approach is that BEM can not describe in detail the three dimensional effects experienced by the blades, giving poor feedback information to the designer. In this paper, the optimization of a HAWT is developed by means of full 3D CFD simulations with the commercial software modeFRONTIER with Fluent integration. The proposed method makes use of some simplifications (i.e.: fully unstructured grid topology, reduced mesh refinement, steady flow, RANS equations) developed by the authors in a past work; this has been done in order to obtain reliable but at the same time affordable numerical computations. Having considerably shortened the computational time required to simulate a single case, a proper optimization technique has been chosen within those available in modeFRONTIER. Starting from initial and pseudo-random solutions, a single objective constrained optimisation has been performed with the aim of maximize the shaft torque at low wind velocity. Results are presented in terms of chord and pitch angle distributions and are compared with a benchmark case available in the literature. The proposed method is recognized able to optimize HAWT (+1.2% available torque obtained) with acceptable required resource (computational power and time) and will be extended in the future works to multi-objective optimisation of small and medium wind turbines. |
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