Optimal Design of a Micro Vertical Axis Wind Turbine for Sustainable Urban Environment

The need for sustainable energy sources becomes greater each year due to the continued depletion of fossil fuels and the resulting energy crisis. Solutions to this problem are potentially in the form of wind turbines, for sustainable urban environment, that have been receiving increased support. At present, a number of wind turbines have been developed that show significant increase in performance compared to existing technologies. From an extensive literature review, a number of key issues have been highlighted which are concerned with the design, optimisation and diagnostics of Vertical Axis Wind Turbines (VAWTs) that have been used to formulate the scope of this research.

A design procedure for a vertical axis wind turbine, that features both multi-blade rotor and fixed outer stator guide vanes, has been derived, in which both rotor and stator blade profiles have been generated for a low wind speed application. In the presented work, numerical investigations have been carried out extensively to determine the optimised design of the VAWT. Sliding mesh technique has been used for the rotation of rotor blades. This new technique captures the transient flow phenomena that occur when the rotor and the stator blades interact with each other. Hence, the results predicted by CFD using this technique are much superior in accuracy. Furthermore, a detailed flow field analysis of the VAWT has highlighted large asymmetries in both pressure and flow velocity about the central axis of the VAWT in both the stationary and the rotating frames of references.

Various geometric parameters associated with the design of the VAWT have been investigated over a wide range in order to analyse the effect of these parameters on the performance output of the VAWT. These geometric parameters are the blade angles, the number of blades in the VAWT and the size of the rotor/stator sections of the VAWT. It has been shown that all these parameters considerably affect the performance output of the VAWT and hence have been optimised in the present study for maximum performance output of the VAWT. One of the key elements of this study is the development of a performance prediction model of the VAWT that takes into account the effects of the aforementioned geometric parameters of the VAWT. This novel prediction model is both robust, user-friendly and has shown to predict the performance output of the VAWT with reasonable accuracy. Hence, the prediction model can be used by the designers of the VAWT.

Nowadays, condition based health monitoring of mechanical systems is topic of vast research. Most of the studies in this field use experimental facilities and conventional toolboxes to handle the output data from the sensors. With the advent of advanced CFD tools, it has now become possible to use CFD as an effective tool for fault detection in VAWTs. An attempt has been presented in this study regarding condition monitoring of VAWTs for sustainable urban environment. Various faults like missing blade and slits in blade have been investigated and analysed. It has been shown that CFD can detect these faults and show the effects of these faults on local flow parameters such as pressure and velocity.