Thesis submitted in fulfilment of the requirements for the degree
MAGISTER TECHNOLOGIAE: Mechanical Engineering
in the
FACULTY OF ENGINEERING
at the
CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2012 / The amount of power a horizontal axis wind turbine (HAWT) can produce is determined by
two main factors, wind velocity and rotor swept area. Theory dictates that the power
production of a horizontal wind turbine is related to the cube of wind velocity and the square
of the turbine diameter (or radius). The power produced at any given time is thus dependent
on of the wind velocity and the rotor swept area of the turbine.
Wind is variable in availability and consistency. Very little can be done to effect the wind
velocity passing through the turbine rotor area and its effect is minimal.
Thus understandably if more power is required, from the same wind velocity, the rotor
diameter must be increased. A variable length blade can adapt lengthwise to accommodate
low wind velocities and similarly high wind velocities during extreme conditions, thus
increasing the operational time and power production of the turbine.
The work undertaken in this thesis is a comparative study between standard design, fixed
length blades to that of a modified design, variable length blade. The project entailed the
design and development of small diameter HAWT blades and experimental testing. The
turbine blades were designed using applicable theory and manufactured from available
materials.
For the experiments, the turbine was mounted on a vehicle and driven at various speeds.
Due to size limitations, no dynamic adaption was done during testing. The variable length
design blade was obtained by cutting increments off.
The results obtained from each test were compared at corresponding points and conditions.
Final interpretation of results lead to the conclusion that by increasing or decreasing the
turbine blade length the area of turbine energy capture can be adjusted to affect the amount
of power produced. Additional benefits included, force reduction during extreme operating
conditions, extended production period for the turbine and a mechanical start up method
during low wind speeds. The financial feasibility did not form part of the scope of this thesis
and the technical feasibility of the concept can be thoroughly addressed in future research.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/1283 |
| Date | January 2012 |
| Creators | Pietrangeli, Sven |
| Publisher | Cape Peninsula University of Technology |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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