The increasing awareness of global warming and climate change, diminishing fossil fuel energy sources, and tightening carbon emission target require the development of renewable energy resources to generate power [1-4].
Over decades, many research works have been carried out to investigate and enhance the power generation
performance of various wind turbine configurations. Most of these research studies have been focused on large scale
horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs) installations in open areas or
fields with a constant undisturbed wind source. However, limited research has been focusing on wind power
generation in built up areas [5-6]. In urban and built-up area, the atmospheric wind becomes highly turbulent and
exhibits significant fluctuations of gust speed and high variability of wind direction caused by the urban structures
and buildings. Under such conditions, existing HAWTs are not effective power generators. On the other hand,
despite having some advantages (fewer moving parts, lower tip speed ratio, quieter, lower cost, & insensitive to wind
direction) over HAWT, VAWTs currently used in urban applications do not produce much more appreciable power
[7]. One of the major limitations of current VAWTs is the negative torque. This restricts the rotor from accelerating
to higher torque producing speeds. There are two ways this negative torque is produced. The first negative torque is
produces on the returning blade (convex side). The second negative torque is produced on the rear blades when the
swept airflow moves through the rotor and tries to exit at the rear. This exiting airflow impedes the returning blade.
In addition, the exiting air stream is directed back into the path of the approaching wind, creating a turbulent zone
which not only introduces losses and minimizing efficiency, but also creates pressure fluctuations that cause
vibrations in the rotor and the surrounding mountings.