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Thursday, May 7, 2015

harnessing wind energy - Coimbatore students awarded patent of a blade

Tilting at windmills is an English idiom which means attacking imaginary enemies.  The phrase is sometimes used to describe confrontations where adversaries are incorrectly perceived, or courses of action that are based on misinterpreted or misapplied heroic, romantic, or idealistic justifications. It may also connote an importune, unfounded, and vain effort against confabulated adversaries for a vain goal.  The phrase derives from an episode in the novel Don Quixote by Miguel de Cervantes, wherein protagonist Don Quixote fights windmills    that he imagines to be giants.

Wind energy is the kinetic energy that is present in moving air. Electricity generation is the process of generating electric energy from other forms of energy. Besides the conventional source of electric generation, there is renewable source of energy – the Wind mills. Tamilnadu has hundreds of windmills nearer Nagercoil and near Coimbatore. Windmill  also Wind Energy Generator [WEG] is a machine that converts the wind energy into electric energy.  Denmark is known to possess the maximum of Windmills.

One important component of WEG is its blades generally made of wood, canvass, fibre. The blades have to be low weight or density to reduce gravitational forces and have high strength to withstand strong loading of wind and gravitational force of the blade itself; they also should withstand  environmental impacts such as lightning strikes, humidity, and temperature.

Wood and canvas sails were used on early windmills due to their low price, availability, and ease of manufacture. Smaller blades can be made from light metals such as aluminium. These materials, however, require frequent maintenance. Wood and canvas construction limits the airfoil shape to a flat plate, which has a relatively high ratio of drag to force captured (low aerodynamic efficiency) compared to solid airfoils.  They have 2 portion – one attached to the hub otherwise nozzle, on the tower – at the other end is the tip attached to the blade through a Carbon Axle Shaft fixed on a Guide Tube through Guide Pin arrangement and Steel Wire which is actuated by a Hydraulic cylinder mounted on the Blade.  The movement of the Tip during activation by Hydraulic Pressure (Axial Displacement of 135 mm and 75 deg Rotation) is controlled by an S-shaped milled Track in Tip Guide.  The Tip moves approximately 135 mm away from the Blade with the help of Carbon  Shaft with Guided Track and Steel wire fastened to Threaded Plug.

The blade is built as self supporting structure comprising of two skin halves mounted around the Main spar. The latter transforming from a Rootspar into Two Y-Spars extending all the way to the Tip.  Shells, Spars and Root sections are made of Fibre glass reinforced Polyster where the main strength properties are achieved by using continuous Fibres called Unidirectional Rowings.  The aerodynamic tip brake is attached to blade portion through a carbon shaft through guide pin arrangement and steel wire which is actuated by hydraulic cylinder.

The blades do get damaged whilst in transit and while in operation causing loss of property as also stoppage in production of wind power.   In a recent post, Times of India reports that students and staff of Park College of Engineering and Technology, Coimbatore  have been awarded a patent by the Indian Patent Office for designing a low-speed windmill blade. The design has the potential to produce power at 3msec wind velocity and stands out from the ones already available in the windmill industry.

A P Haran, K Prasanna, P Mani Bharathi and Karthik V were awarded the patent last week for designing the windmill blade. While Haran and Prasanna are faculty members of the aeronautical engineering department, Mani Bharathi and Karthik are alumni of the institution, who worked on the project for almost three years.  Mani Bharathi and Karthik, who belong to the 2008-2012 batch of BE aeronautical engineering, were keen on doing something in the field of renewable energy . “There were long power cuts during the period, and everyone was looking for alternative sources for power. Solar and wind energy started gaining importance at that time,“ said Karthik. This was the motivation for the duo to suggest an idea to A P Haran, the dean of mechanical sciences. The students along with Prasanna K, an assistant professor with the aeronautical engineering department, studied some designs made by Indian windmill companies, and some designs from China and Japan, too.

“We found that windmills had difficulty producing power at low wind velocity and this was the challenge we took up for our design,“ said Bharathi. The team then identified parameters like weight, material and aerodynamics of the blade. Dean Haran said that they attempted to sell the blade design to some windmill companies, but had a better offer waiting for them.

With regards – S. Sampathkumar

30th Apr 2015.

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