Abstract:
The proposed mechanism is made more efficient by minimizing the friction and
the force required to tilt the blades and by ensuring perfect blade orientation. A
workable prototype design features rotatable blades on horizontal shafts connected
to a vertical axis, with a wheel-and-track system linked to a yawing mechanism
that turns the blades with wind direction. The turbine was fabricated using
readily available materials such as PVC pipes, fittings, cardboard, metal sheets,
etc.
The wind speed just before (V1) and after (V2) both sides of the turbine were
measured at several wind speeds generated by a wind source. The V1:V2 (m
s-1) results are: 2.1:0.6, 2.4:0.8, 2.5:0.9, 2.7:1.0, 3.0:1.3, 3.2:1.5, 3.5:1.7, 3.9:1.9.
Then the energy available in the blowing wind before and after passing the side
of the turbine that captures the wind was calculated. The difference is the energy
captured by the wind turbine. A part of this absorbed energy is consumed for
the operation of the tilting mechanism. Since both sides of the tilting blades
are well balanced, there is minimum or no energy consumed for lifting a blade.
The only factor that consumes energy is friction. If friction is minimized, the
captured energy can be assumed to approach the mechanical energy generated by
the turbine.
The calculated power coefficient values for each incoming wind speed are:
0.98, 0.96, 0.96, 0.95, 0.95, 0.93, 0.92, 0.90, 0.89, 0.88. These results show that
the Betz limit of 0.59—defined as the maximum efficiency that can be achieved by
any Horizontal Axis Wind Turbine (HAWT)—is exceeded by this VAWT. From
the results, it can be concluded that the efficiency of capturing wind energy of this
new VAWT is higher than that of conventional Horizontal Axis Wind Turbines
(HAWT), which are the most common in commercial use.
