IMPLEMENTATION OF A VERTICAL AXIS WIND TURBINE

Presentation on IMPLEMENTATION OF A VERTICAL AXIS WIND TURBINE

RENEWABLE ENERGY

RENEWABLE ENERGY IS ENERGY GENERATED FROM NATURAL RESOURCES—SUCH AS SUNLIGHT, WIND, TIDES, AND GEOTHERMAL HEAT—WHICH ARE RENEWABLE. NOW A DAYS RENEWABLE ENERGY IS ONE OF THE MOST IMPORTANT TOPIC IN POWER GENERATION.

ADVANTAGES OF RENEWABLE ENERGY

1. We can use it repeatedly without depleting it.
2. No contribution to global warming.
3. No polluting emissions.
4. Low cost applications when counting all costs.
5. Saving on health and its costs.

RENEWABLE ENERGIES

1. KNOWN RENEWABLE ENERGIES ARE
2. SOLAR
3. WIND
4. BIOMASS
5. HYDRO etc…

TYPES OF WIND TURBINES
Horizontal axis
Turbines that rotate around a horizontal axis are more common. Horizontal-axis wind turbines (HAWT) have the main rotor shaft and electrical generator at the top of a tower, and are usually pointed into the wind
Vertical axis
Vertical-axis turbines rotate on a vertical axis.
VERTICAL AXIS
Vertical-axis turbines rotate on a vertical axis. Vertical-axis wind turbines (or VAWTs) have the main rotor shaft arranged vertically. Key advantages of this arrangement are that the turbine does not need to be pointed into the wind to be effective. This is an advantage on sites where the wind direction is highly variable. VAWTs can utilize winds from varying directions.
VAWT SUBTYPES

1. DARRIEUS WIND TURBINE
2. GIROMILL
3. SAVONIUS WIND TURBINE

ADVANTAGES

1. A MASSIVE TOWER STRUCTURE IS LESS FREQUENTLY USED.
2. THEY HAVE LOWER WIND STARTUP SPEEDS THAN HAWTS.
3. THEY MAY BE BUILT AT LOCATIONS WHERE TALLER STRUCTURES ARE PROHIBITED.
4. VAWTS SITUATED CLOSE TO THE GROUND CAN TAKE ADVANTAGE OF LOCATIONS.
5. THEY MAY HAVE A LOWER NOISE SIGNATURE.
6. SIMPLE MANTAINENCE.
7. SIMPLICITY OF MANUFACTURE AND INSTALATION.
8. DOES NOT DEPEND ON WIND DIRECTION

VAWT DISADVANTAGES

1. MOST PRODUCE ENERGY AT ONLY 50% OF THE EFFICIENCY OF HAWTS IN LARGE PART BECAUSE OF THE ADDITIONAL DRAG THAT THEY HAVE AS THEIR BLADES ROTATE INTO THE WIND.
2. A VAWT THAT USES TO HOLD IT IN PLACE PUTS STRESS ON THE BOTTOM BEARING AS ALL THE WEIGHT OF THE ROTOR IS ON THE BEARING.
3. HAVING ROTORS LOCATED CLOSE TO THE GROUND WHERE WIND SPEEDS ARE LOWER DUE TO WIND SHEAR, THEY MAY NOT PRODUCE AS MUCH ENERGY AT A GIVEN SITE AS A HAWT WITH THE SAME FOOTPRINT OR HEIGHT.

DARRIEUS WIND TURBINE
FOR IMPLEMENTING PURPOSE WE CHOOSE THE DARRIEUS TYPE VERTICAL AXIS WIND TURBINE. THE REASONS BEHIND IT ARE GIVEN BELOW.
DARRIEUS TURBINES, WHICH ARE LIFT-DRIVEN, HAVE A HIGHER POWER POTENTIAL THAN THE HORIZONTAL, OR DRAG-DRIVEN TURBINES. THE MAIN DRAWBACK WITH THEIR DESIGN IS THEIR INABILITY TO SELF-START. DARRIEUS TURBINES REQUIRE AN EXTERNAL ENERGY SOURCE TO BRING THE DEVICE TO A MINIMUM ROTATIONAL SPEED
COMPONENTS
Base: The base will be a truncated pyramid, about 3ft tall. This base was made by angles. It has different levels, one at ground level, one hold the way up and one at the top. There is two bearing mounted in the top and bottom of the top levels.

Shaft: Sitting in these bearings will be the shaft. The shaft is a 9ft tall length of steel mechanical tubing, with initial dimensions of 1” in the main part, 0.75” at bottom.
Blades: The dimensions of the blades are 20inch in length and 10inch in wide. Eight prototype blades were made to connect to the turbine. The blades were connected to the turbine body by two nuts at the bottom and the top.

Turbine structure : Attached to the shaft by set screws are 2 circle of steel bar which. These were fabricated at the workshop. The circles are joined to the shaft by two small circles.

GENERATOR
IN THIS DESIGN WE USED A PERMANENT MAGNET DC MOTOR. IT WAS REQUIRED TO USE SYNCHRONOUS GENERATOR BUT WE USED PARMANENT MAGNET MOTOR BECAUSE IT IS AVAILABLE IN THE LOCAL MARKET.

FINAL SETUP

WIND POWER CALCULATION
WIND POWER, P = 0.5 X RHO X A X V³
WHERE,
P = POWER IN WATTS
RHO = AIR DENSITY (ABOUT 1.225 KG/M³ AT SEA LEVEL, LESS HIGHER UP)
A = ROTOR SWEPT AREA, EXPOSED TO THE WIND (M²)
V = WIND SPEED IN METERS/SEC
WIND TURBINE POWER
P = 0.5 x rho x A x Cp x V³ x Ng x Nb
Where,
P = power in watts.
rho = air density.
A = rotor swept area, exposed to the wind (m²)
Cp = Coefficient of performance
V = wind speed in meters/sec
Ng = generator efficiency
Nb = gearbox/bearings efficiency.
WIND SPEED VS. TURBINE POWER

FUTURE IMPROVEMENTS
While the prototype did not perform as well as initially hoped, with a few changes to the design this should improve greatly:

1. The most important area of improvement is the turbine body construction, which could have been done by aluminum.
2. The blades are not perfectly shaped by making the blades perfectly shaped the efficiency of the turbine can be improved
3. Change that would improve the performance is altering the design of the arms.
4. Some of these improvements would be to purchase better bearings, install better bearing support, and add weatherproofing. A better bearing would enable the turbine to turn more freely; reducing the starting torque and making everything work much more smoothly

Submitted by SAYEDUR RAHMAN and SAQUIB SHARIF