Cooperation between IFS and Dezineforce on optimisation of wind turbine design - March 2009
Significant natural reservoirs of kinetic energy exist within tidal waterways, ocean streams, rivers, and off-shore winds. Zero-head wind and water turbines are becoming increasingly important in producing renewable energy from these sources. However, developing an in-depth understanding of turbine efficiency in zero-head flows is important for both device optimisation and the assessment of the economic viability of the energy production.
Wind power is arguably the most mature of the currently available renewable energy technologies and has had the greatest success in breaking into practical large scale energy generation. However, the overall efficiency of the power generation system remains a critical component of the overall economic justification for a potential installation. Similar technology has been adopted for water turbines, and a similar trend has been evident within this industry.
There is therefore significant interest in the development of prediction methodologies that are capable of addressing the in-situ performance of multiple turbine installations within a specific local environment over a range of operating conditions. The underlying dynamics of the fluid flow processes and interaction of multiple installations is therefore a key component of the overall efficiency of the installation. Computational Fluid Dynamics (CFD) has been identified as a key technology that could provide both the assessment of an individual turbine design and the performance multiple installations.
In comparison to the other, semi-empirical methodologies, CFD offers probably the most scientific approach. Although, CFD modelling of even a single wind turbine requires sophisticated analysis software coupled with significant computational resources, the technology has the potential to capture the full complex three-dimensional physics for the most demanding operational conditions. With falling costs of computational resources, the use of CFD as a design and assessment tool is becoming increasingly practical within an engineering environment. Furthermore, there is the potential of coupling the fluid flow CFD model with a structural mechanics model to perform a complete fluid-structure interaction simulation which fully represents the physics of the real system. This enables analysis of turbine deformations due to aerodynamic loading and their subsequent effect on the performance of the installation.
In addition, CFD simulations can be used to generate input data for a semi-automatic design optimisation process. With use of modern tools, an engineer can perform the optimisation tasks virtually automatically and remotely, over the internet. This reduces the need for user interference and offers additional possibilities on different levels of the design process and operational analysis. It simplifies the development of suitable blade profiles to accommodate a variety of flow conditions. The technology also enables the selection of an optimum blade orientation in order to maximise torque. On a wider scale, the efficiency of a wind farm depends on the positioning of the wind turbines to minimise the interference due different environmental conditions and wake shading. The automated optimisation process can predict the optimal wind farm arrangement and to reduce the risk in project development.
