Transient Flow Features in the Vicinity of a Vertical Axis Wind Turbine

The increasing demand of energy in the world is driving the search for more renewable and
sustainable energy sources. Renewable sources of energy are being explored globally to overcome the depletion of fossil fuels and the resulting energy crisis. Moreover, use of fossil fuels has significant negative effects on the environment. Therefore, the focus is currently on both to ensure long-term energy supply, as well as to monitor and minimise the negative effects of these sources on the environment. In order to meet renewable energy targets, harnessing energy from all available resources such as wind, (through wind turbine), is necessary. Wind energy is one of the important sources of renewable energy. Wind turbine technology has been developed continuously, but the maintenance of wind turbines is still a topic of interest. Horizontal axis wind turbines (HAWT) have dominated the wind energy and high power generation characteristics. However, vertical
axis wind turbines (VAWT) are also gaining wide acceptance owing to being capable of producing power even at low speeds.
The present study focuses on the quantification of the effect of steady wind flow conditions
on the performance of Savonius type vertical axis wind turbine. The Savonius vertical axis
wind turbine considered in this study comprises of multi-blade rotor and stationary inlet guide vanes, with the arrangement most suitable for a low wind speed application. Advanced numerical modeling tools within ANSYS–Fluent have been used in the present work to simulate the flow in and around the Savonius vertical wind turbine in order to quantify the flow behavior. Sliding mesh technique has been incorporated to simulate the rotation of the rotor blade, which capture the flow phenomenon caused by the stator and the
rotor interaction, and hence providing more accurate results. A critical analysis of the flow across vertical axis wind turbine has been conducted through investigating the static
pressure and velocity magnitude variations in the vicinity of the wind turbine.
Furthermore, the present study has also focused on the performance of a vertical axis wind
turbine under unsteady flow conditions whereby the flow is accelerated and decelerated as
characterised by the change in the wind velocity. The torque and power generation
capabilities of the turbine have been characterised and in particular the rotor contribution has been quantified. The effect of transient phenomena under varying torque outputs during accelerating and decelerating flows has also been highlighted. Overall performance of the turbine has also been quantified.