Aérojoules project: Vertical Axis Wind Turbine

Abstract

The objective of the Aérojoules project is to optimise the design of a Darrieus type Vertical Axis Wind Turbine and assess its validity of use as small scale electrical power generation in the ‘Pay de la Loire’ region. It is well known that flow phenomena over a VAWT is complex and difficult to predict. A good understanding of flow characteristics is needed to predict torque and net power at various wind speeds, minimise stall effects, allow reliable starting, minimise loads and in particular fluctuating loads leading to excessive fatigue, understand tangential and radial forces and identify flow characteristics in the wake of the turbine to better understand interference effects. Detailed 3D unsteady CFD analyses has been undertaken using the CFD program Star CCM+ to better analyse and predict flow over a VAWT. Such analysis has been compared with published articles and model tests with the aim to provide a reliable model for future applications. Also detailed model testing has been conducted in a wind tunnel at various angles of attack, to measure lift forces and understand flow characteristics. Further wind tunnel testing has been conducted at full scale and compared with predicted results. A good comparison between static and dynamic foil wind tunnel behavior as well as between model and full scale is obtained. The designed turbine uses a fixed pitch, yet helicoidal 3-bladed VAWT made of composite material. Its use in the marine industry and in particular on cargo ships is further investigated. It is also compared with a concept design which alters the angle of attack of the turbine over a rotation, allowing better control of turbine characteristics for a more reliable prediction of performance.