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EXPERIMENT - METHOD

Make a Blade

The winds of 2～7m/s blow to the wind tunnel that was completed, and aim at a windmill. The wind is rectified by honeycomb structure, so I can measure in laminar flow.

Measuring

In the experiment, I measure a number of wing’s revolutions for reference. If a tire diameter is 26inches and 15km/h, hub-dynamo power is rated voltage 6V, rated output 2.4W and 120rerolution per minute. Measure the winds from wind tunnel by an anemometer, and adjust to the wind of 2～7m/s. Record output electric power.

Below to the right of picture is an anemometer, above to the right of picture is a number of revolutions meter. They costs both \2000～\3000. (Akihabara electrical appliance store area)





The upper picture is a scene of measuring by tachometer.
　　　　　　　　　　　　　　　　　　　　　
Measure output electric power every wind speed 2～7m/s. (Tester)


Relation between wind speed and output of a flat board blade(butterfly's wing)hub-dynamo windmill

(upper section is wind speed)
(lower section is output)



Relation between wind speed and output of a dragonfly’s wing-shaped blade hub-dynamo windmill

(upper section is wind speed)
(lower section is output)


Blade

Flat board blade (butterfly's wing)　
Prepare a P.P board (2.5mm thickness), and make a blade of 10cm wide × 35cm long. (Mass is 25g) Cut accurately by cutter, and bend a claviform part by putting in boiling water. In this experiment, I prepare a wooden model (like the legs of a kotatsu) in advance. And I shape it by pressing a hot P.P board.

Dragonfly’s wing-shaped blade
A condition for making is the same as a flat board blade(butterfly's wing). Notch a blade by bending it.

Wind tunnel experiment (A charge in a Reynolds number) ①










When wind speed of flat board type(butterfly's wing) and dragonfly’s wing type “U” is 2m/s, this picture was taken. A Reynolds number “Re” is 76. It is said a laminar flow although it reach the very limit.


Wind tunnel experiment (A charge in a Reynolds number) ②










When U is 4m/s and Re is 152, this picture was taken. A Karman’s vortex street is visible faintly at the back. I tried in case of U = 7m/s and Re = 266, but it doesn’t become a perfect turbulent flow. A reference book says that Turbulence occurs when the Reynolds number exceeds about 2000.

Future prospects


By this experiment , I can make a dragonfly’s wing-shaped blade which is better than six flat board wing-shaped blade. So, I add more this. I made a wind power generator which is attached a wind lens. I will entry wind power generation competition by this windmill, and I want to get one of the top.


Electric power which is generated by dragonfly’s wing and wind lens windmill is over 2000mW. So, I rectified from AC to DC by full-wave rectification circuit, and I made new system that can change cellphone and USB equipment. I also made an LED accumulation of electricity light can save up electric power to a charging battery as a light for prevention of damage by disaster.

　　　　　　　　　　　　　　　　　　　　　　　　　








　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
Postscript
Finally, I made converging wind equipment and a blade fitted a winglet so that the generation of electricity efficiency goes up. Then I entried the competition.

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