Week 5

The graph above shows a theoretical output of both a Savonius Wind Turbine (blue) and a traditional horizontal axis wind turbine against wind speed. The average wind speeds in Africa range between 5 and 20 km/h, but the graph considers extremities of wind speeds up to 35 km/h.

The data was calculated using the following formula, which is the general formula for calculating the revolutions per minute in a wind turbine:

Where λ is the Tip-Speed Ratio

(Source: http://www.raeng.org.uk/education/diploma/maths/pdf/exemplars_advanced/23_wind_turbine.pdf)

The revolutions per minute is directly related to the power and this was calculated using http://www.windstuff.org/calc/calc.php

A simple analysis of the graph shows that both turbines produce similar energy output values, though the Horizontal Axis Turbine is slightly more efficient at higher wind speeds. However, this is not a factor that discredits the choice of a Savonius Turbine over a Horizontal Axis turbine as both of these turbines would probably break down at such high wind speeds.

            Thus, this graph helps to show that the turbine design is sufficiently efficient. The power rating of a wind turbine ranges between 250 watts and 1.8MW. Though the designed turbine’s power rating does not meet up to those, it was only made as a proof of concept and 50% of professional standard output is sufficient to be considered successful. However, it must be noted that these are optimal condition output ratings and errors in design or natural factors may considerably affect the data.