Friday, January 7, 2011

Unfolding of the helical Savonius blade

Manufacturing of the blade of helical Savonius is not easy or not economic. In our mini-project in the faculty we faced this problem "How to make the blade". We (the team work) thought a lot, and most of the techniques were depending on discretization criteria. Our instructor told us "try to unfold the blade and you may get the help from any mathimatician". I searched over the internet and found a patent named "Helical wind rotor and a method for manufacturing the same". The patent number is US 6,428,275 B1 (you can find it in .

The main problem in this patent that it requires converting the blade profile (section) to parametric equations and  solving simultaneous non-linear partial differential equations.

After a lot of work, I were able to unfold the blade using simple method (some Scilab codes) and the results were convincing and looks like that obtained in the patent.

The previous figure shows the unfolding of the a helical blade of 80 cm height, 30 cm bucket diameter, and 5 cm primary gap.