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WHICH WINDMILL BLADES ANGLE IS MOST EFFICIENT

Researched by Michael E. 
1998-99

 

PURPOSE

The purpose of this experiment was to find out which blade size and angle is most efficient.

I became interested in the idea when I learned that windmills are non-pollutant to the environment.

The information gained from this experiment will benefit society by knowing which blade size and angle will generate the most electricity.

 


 

HYPOTHESIS

My first hypothesis is that the closer the blade is to 45 degrees the more electricity the windmill will produce.

I base my hypothesis from information gained while reading literature on windmills.

My second hypothesis is the bigger the blade, the more electricity the windmill will produce.

 


 

EXPERIMENT DESIGN

The constants in this study were:

  • Same windmill
  • Same fan (wind generator)
  • Same DC ampmeter
  • Same electricity generator
  • Same wind speed
  • Same fan distance (1 meter) from the blades

The manipulated variables were the angle and the length (blade area) of the blade.

The responding variable was the electrical output of generator attached to the windmill.

To measure the responding variable, I am going to hook a ampmeter to the motor and record the electrical current output.

 


 

MATERIALS

 

QUANTITY 

ITEM DESCRIPTION

 Electrical wires

Rubber band (pulley)

1

Fan (wind source)

 

 Tape measure

 Windmill (Homemade from Tinker-Toys and Erector Set)

Ampmeter (Measured current output)

Protractor (Measuring blade angle)

Electrical generator

5cm x 1cm blades

10cm x 1cm blades

15cm x 1cm blades

20cm x 1cm blades

 

 


 

PROCEDURES

1. Build the windmill out of Tinker-Toys and Erector Set. 
2. Cut out four of each of these; 1 inch, 2 inch, 3 inch, 4 inch, and 5 inch. long  blades out of vaneshen blind blades. 
3. Place fan approximately 1 meter away from windmill. 
4. Attach all of one size to the propeller holder. 
5. Measure the degree of the blade with a protractor. 
6. Make sure the blades are at 0 degrees (parallel with other blades). 
7. Attach ampmeter wires to the motor. 
8. Turn the fan on and take notes on DC current. 
9. Read the voltmeter to tell how much electricity has been produced. 
10. Repeat the above but change the angle of the blade to 15, 30, 45, 60, 75, and 90 degrees. 
11. Repeat the above with the 5 inch long blades set at 0 degrees. 
12. Repeat the above with the 10 inch long blade set at 0 degrees. 
13. Repeat the above with the 15 inch long blade set at 0 degrees. 
14. Repeat the above with the 5 inch long blade set at 0 degrees. 
15. Collect the data and make graphs of current output vs. blade area and angle. 


 

RESULTS

The original purpose of this experiment was to find out which blade size and angle is most efficient.

The results of the experiment were that the closer the angle of the blade to 75 degrees; the more electricity was produced for all blade sizes except 100 cm2.  At 75 degrees, The 300 cm2 blades were most successful generating 57 dc milli-amps. The 200 cm2 blades were second most successful generating 52 dc milli-amps. The 400 cm2 blades were second best in generating 51.3 dc milli-amps. If you put the hub of the windmill and have the blades attached to it, it will show that the span of the 400 cm2 blades are bigger than the wind generator. This could explain why the 400 cm2 blades did not create as much electrical current as the 300 cm2 blades.  The 100 cm2 blades did not spin at any of the 7 different angles because the total area of the blades was too small to catch the wind.  The wind force was not strong enough to overcome the sluggishness of starting the motor.

At 90 degrees, there was no current generated at any of the blade lengths.  The blades were perpendicular to the wind.  This indicated the blades need some sort of an angle to the wind to turn the generator.  At blade angles less than 75 degrees, the generator still had a current output but not as strong as the 75 degree blade angle.  As you approach 0 degrees blade angle from the 75 degree blade angle, there is a progressive decrease in the DC current output.  At 0 degrees blade angle, the blades twitch a little bit but there was no DC current output because the blades presented a flat surface to the wind.

This experiment showed me that a windmill must have the optimum angle and blade surface area to generate electricity.
  
 

 


 

CONCLUSION

My first hypothesis is that the closer the blade was to 45 degrees; the more electricity the generator will produce.  The greatest amount of electricity was produced at the 75 degree blade angle for all four blade areas. The results indicate that my first hypothesis should be rejected because at 45 degree blade angle; the amount of electricity generated was less than at 75 degree blade angle.

My second hypothesis is the bigger the blade, the more electricity the windmill will produce.  The 300 cm2 blades caused the most electrical output from the generator.  The 400 cm2 blades had a smaller electrical output than 300 cm2 blades.  The 400 cm2 blades were a too big for the windmill. The wind generator blade span was smaller than the 400 cm2 blade span.  This made it difficult for the 400 cm2 blades to turn the generator.  The 300 cm2 blades were just the right size for the wind generators wind span.  My second hypothesis should also be rejected because the 300 cm2 blades made more electricity than the 400 cm2 blades.

I wonder if blades wider than 1cm would increase the electrical current output of the generator.  Also if I were to conduct this project again, I would use a bigger wind source (fan) so that I could get the windmill or windmills to create more electricity. 


 

RESEARCH REPORT

INTRODUCTION

 Not all windmills are the same.  Some turn or turned grindstone, some pump water, and some make electricity.  Windmills have basically the same design since 1933.  There are only three types of windmills today.  In the early 1900ís over 700 different water pumping windmills were being made. During the 1930ís, an 8-ft windmill cost $25.00 dollars, now that same windmill cost $1,455.00.  Windmills went out of fashion in the early 1940ís.  Windmills are really wanted in rugged lands or places without electricity. Some people still have old windmills.

WINDMILLS

The first windmills were used for irrigation about the 5th century AD in Persia.  By the 12th century BC windmills had spread around Europe.  The early European windmills turned grindstones or pumped water.  The Dutch windmills were made of wooden frames and canvas was stretched to make a sail.  In the late 19th century in Europe thousands of windmills were being used. In the 1980ís more than 30 companies were manufacturing wind machines.  The smaller windmills on small platform seem to be more successful than the bigger windmills.  Wind farms are made of anywhere from 60 to 1000 windmills in a big area. The big wind farms present problems such as noise, pollution, and disruption of radio or television although it doesnít present a problem for wildlife unless they have to cut down trees.

DENMARK

By the year 2030 Denmark will have the largest investment in wind generation.  They are finding ways to make offshore foundations right now.  By 2030 well over 100% of their populationís power will be coming from offshore windmills.  All of the windmills will be either in the North Sea or the Baltic Sea.  They have ideas for three different offshore foundations for the windmills.

KINDS OF WINDMILLS

There are two classes of windmill turbines, horizontal-axis machines and vertical-axis machines.  There is one more windmill blade that has a principle of an airplane wing to make rotation.  They are driven by wind simply striking the blades.  An example of horizontal-axis is machines that are multi-bladed windmills of the US Prairies.  They are primarily used for pumping water, modern two-three blade lift devices like huge airplane propellers.  These devices have rotors of 90m (295 ft) or more in diameter.  The propellers can be 5 to 6 times the winds velocity.  The Oasis 3 is one of the only windmills out today.  It has 24 10-inch blade that are hooked to a hub.  It has a maximum speed of 100 RPM.

PROPELLERS

Propeller- A propulsion device usually used on ships and planes.  Propeller is series of blades on a hub that is mounted on an engine-driven shaft (or wind).  The rotation of blades in water or air produces a forward thrust.  In the 1920ís George Darrieus, a French inventor, invented an efficient wind turbine.  It was called the ìDarrieus Wind Turbineî.  It looked like an eggbeater with two or three curved blade that hooked to the shaft.  It catches the wind from all directions.  The Mod-2 a government funded test windmill has 91m (300 ft) long propellers.  It is 25 stories tall.

CONCLUSION

Windmills have been around for thousands of years.  Some were failures; some were not.  It all depended on how and what they used to build them.  The first windmills were used for irrigation about the 5th century AD in Persia. In the 1920ís George Darrieus a French inventor invented an efficient wind turbine.  There are two classes of windmill turbines, horizontal-axis machines and vertical-axis machines.  By the year 2030 Denmark will have the largest investment in wind generation.

 


 

BIBLIOGRAPHY

 

ìBernoulliís Law.î Grolier Interactive Encyclopedia, CD, 1998

Danish Wind turbine Manufacturing Associate. ìOffshore Foundations: Mono Pileî [Online] Availablehttp://www.windpower.dk/tour/rd/monopile.htm

Julian, John. ìProject.î[Online] JSki184@aol.com from johnj@nts-online.net, January 6,1999

ìPower.î Grolier Interactive Encyclopedia, CD. 1998

ìProduct Description.î http://www.windmillpower.com/product-info.html. January 12, 1999

ìPropeller.î Grolier Interactive Encyclopedia, CD.1998

Settles, Gary S. ìPropellerî, Grolier Interactive Encyclopedia. 1998, CD

ìWindmill.î The World Book Encyclopedia. 1994. Vol. 21. pg. 335

ìWindmills and Windpower.î Grolier Interactive Encyclopedia, CD. 1998 

 




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