THESIS
2017
xi, 158 pages : illustrations ; 30 cm
Abstract
This research focuses on developing a lightweight and high performance cement-based
composite for use in a new innovative floating-type vertical axis wind turbine (VAWT). This
particular wind turbine has a bowl-shaped rotor floating on a fluid (water or air). The blades
are mounted on the rotor structure, which rests over the fluid, which eventually sustains the
total load. The bowl-shaped (semi-spherical) base whose rotation is facilitated by the fluid on
which it rests rotates the blades, under the action of wind. The composite to be designed for
the wind turbine must be lightweight and possess high strength and stiffness.
A lightweight thin laminated composite, incorporating cementitious mortar matrix, reinforced
with Fiber Glass and Galvanized Iron mesh as main flexural rein...[
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This research focuses on developing a lightweight and high performance cement-based
composite for use in a new innovative floating-type vertical axis wind turbine (VAWT). This
particular wind turbine has a bowl-shaped rotor floating on a fluid (water or air). The blades
are mounted on the rotor structure, which rests over the fluid, which eventually sustains the
total load. The bowl-shaped (semi-spherical) base whose rotation is facilitated by the fluid on
which it rests rotates the blades, under the action of wind. The composite to be designed for
the wind turbine must be lightweight and possess high strength and stiffness.
A lightweight thin laminated composite, incorporating cementitious mortar matrix, reinforced
with Fiber Glass and Galvanized Iron mesh as main flexural reinforcement, has been proposed.
The composite has been designed according to merit index M
b = [E/ρ]
1/2, which corresponds
to the strength, stiffness and density of the composite, and the desirable minimum value of
merit index is 0.003. A new lightweight filler, Fly Ash Cenosphere (FAC), has been
incorporated in the cementitious mortar matrix. The developed composites were evaluated for
mechanical properties (compression, flexure, toughness, and tension), durability (fatigue) and
microstructural characteristics (SEM, EDX, MIP, BET, TGA, and DTA). The reasons for
improved specific strength of the developed composites were investigated and the properties
modelled with the fore mentioned complimentary techniques. Further, nano silica was used to
enhance mechanical and interfacial properties thus improving the overall composite behavior.
The developed laminated composites were also evaluated for flexural fatigue behavior under
various stress levels, and the fatigue life predictions for various probabilities were determined.
Lastly, the blades for VAWT were fabricated of the optimized cementitious mortar mix, and
the performance tested in a wind tunnel. It was found that the developed composites could be
useful for wind energy harvesting when used in the VAWT, however, the power coefficient
was not high enough due to heavier overall loading on the rotor base. Therefore, a novel
compressed-air floating-bowl-shaped design of VAWT is proposed which is expected to
overcome the power efficiency issues.
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