Small Wind Turbine Blade Optimization for Smooth Starting Performance in Low Wind Speed Regions
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Date
2021-02
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Addis Ababa University
Abstract
Access of electricity in the developing country is a big issue that the government highly
concerned. Small wind turbines are one of the alternative the government have in order
to address electricity specially in rural areas. Wind turbines are highly dependent on wind
speed, hence the areas with low wind speed region can not access the electricity as expected.
This is because the turbine works in low wind speed range which gives the annual energy
production more less than the desired output.This thesis investigate the way how to get the
optimum energy output from small wind turbines by lowering the time at which the wind
turbine starts rotating and generating electricity with out decreasing performance of the
turbine.
The main objectives of the thesis were starting time and coe cient of performance and
the parameters used for the optimization processes were chord value, twist value and type
of airfoil. Two non optimized blade with single and mixed airfoil section are designed with
usual designing procedure by using horizontal axis wind turbine design code credited to
Oboe Daniele and Marinoni Andrea. Three optimized blade which have 0.8466m, 0.5m,
and 0.5m radius with the rst two blades have SG6043 airfoil section and the third one has
SD7062 airfoil section are designed. The optimization is taken by multi objective genetic
algorithm and di erent input criteria like airfoil type, blade number, starting wind speed,
resistive torque is taken for a better investigation. Beside to analysis of the optimized and
non optimized blade, the e ect of weight given to starting, genetic algorithm parameters,
limiting the boundary of twist and chord value, airfoil, designing the blade with single
and mixed airfoil, blade number, and starting data are well investigated. Non optimized
3-bladed, SD7062 airfoil section blade starts in 16.3sec at 5m
s wind speed while the Optimized
blade with the same blade speci cation starts at 8.63 second which means there is 88.8%
improvement in starting time but the coe cient of performance only decreases from 0.34
to 0.335, which means its percent reduction is 1.49% . From previously conducted research
on starting performance with the same input criteria with this thesis by (1) which gets
87% improvement in starting time and 1.6% reduction in coe cient of performance. This
research shows improvement by altering airfoil type, chord and twist value.
The optimum blade which have lowest starting time and better power performance
was manufactured from Australian timber by Computer numerical control machine and
experimental testing was conducted. In order to get constant wind speed ow, a controlled
moving vehicle was used for the experimentation process. The starting time and coe cient
of performance of the blade from the software were 8.63sec and 0.335, while the experimental
result gives 9sec and 0.3228. This shows there is a 3.61% and 4.2% error while testing in Cp
and starting time respectively. Value of errors comes from rst the generator, since it needs
to be excited it makes some delay on recording some seconds as it starts generating electricity.Beside to excitation the generator is used and maintained repeatedly, this makes it to do
not perform as it is rst manufactured. There is also some manufacturing and assembling
di culties while making parts and assembling the wind turbine which add some contribution
on the performance of blade under experimental testing. Finally the manufactured wind
turbine produce 19.4W electrical power at 5 m
sec which is the frequent available wind speed
in low wind speed region(2).
Description
Keywords
Optimization, Starting time, Coecient of performance