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The STEM students in my class were to review two different presentations dealing with renewable wind energy and wind turbines. We were to write a summary about these slides in order to get a general idea about how wind energy is utilized in society today, how turbines are constructed, and what exactly is the most efficient way to capture the energy of wind. The first presentation was Wind 101. It explained the basis of wind turbine design and how the energy captured is utilized in today's world. The second presentation was Wind Energy Technology and basically explains how different designs of turbine blades affect the energy output of that turbine.
Wind 101 Presentation:
Wind Energy Technology Presentation:
The wind presentations promote the advances and benefits of wind power to human society. Wind turbines can be very educational to students who want to learn more about wind energy. It would open up jobs and opportunities in this field. The industry for wind energy is the fastest growing energy source industry in the United States of America. Engineers are very excited for this and are constantly creating new, more efficient designs for wind turbines. However, this renewable energy source is not without its own limits. People believe that wind turbines are an eye soar, generate way too much noise, and kill birds. Actually, this is not true. Wind turbine designs have been made into an art by many engineers. They are also developing silent rooftop turbines. Also, wind turbines actually do not kill birds. In fact, they cause the fewest avian deaths. By not using wind and more clean energy sources, global warming will increase and kill off birds and other wildlife.
Original Turbine Design
After being presented with this information, my class was instructed to build a standard turbine. The blades of the turbine were to be a rectangle of two inches by six inches made out of cardboard. We then hot glued those blades onto wooden dowels, stuck them into a black hub. We made bases out of PVC pipes and put motors, that were connected to the hub, into the PVC pipe with wires running through it.
Power Calculations
Afterwards, we learned how to calculate the theoretical power and electrical power of a turbine as well as Ohm's Law for power. The calculation for theoretical power is P=1/2pA(v*v*v) where P is power in watts, p is the air density in kg/m*m*m, A is the swept area of the blades, and v is the velocity of the wind. The calculation for electrical power is P=IV where P is power in watts, I is current in amps, and V is voltage in volts. Ohm's Law is V=IR where V is voltage in volts, I is current in amps, and R is resistance in ohms. We also learned how to use a multi-meter in order to calculate the amount of voltage, resistance, and current the turbines were generating. The class concluded, based upon these equations, that the next way to reach the optimum design for power was to increase the velocity of the wind.
Redesign Turbine
When we finally got to redesign our turbines, we were only given the ability to change the design of the blades. The tower, velocity of wind, and air density had to be constants. My group consisted of myself and two other students, Kali and Seda. We decided to focus on the aerodynamics of the blades rather than the length of them. A wider blade would be able to catch the wind better, as well as bending the actual blade. The twist in the blade would cause the wind to glide over the blade, reducing the amount of drag acting on it. Sadly, due to our inability to gain more materials, my team had to discard that idea. We only had cardboard to use which was very hard to get to stay in a bent position. Instead, we cut the blades on a diagonal and slanted them at an angle when we assembled them onto the turbine.Our redesigned blades were three inches wide and five inches long with a diagonal cut from one inch in on the top of the blade to one inch in on the opposite side. Later, right before we were to test out our new designs, we realized that we actually shortened the blades and the swept area, but it was too late to change it. To fix this problem, we glued the blades farther from the rotor on the dowels, or the wooden sticks. This is our final redesign.
Test It!
The standard turbine had 1.206 Watts of theoretical power and 0.0476 Watts of electrical power. The new wind turbine design had 0.41877134 Watts of theoretical power and 0.053978 Watts of electrical power. We recorded this using a multi-meter and the calculations for Theoretical Wind Power, P=1/2pA(v*v*v), and Electrical Power, P=IV.
The point of this lab was a competition between all the teams in the class to create the turbine that could generate the most power. There were nine teams consisting of two or three students each. We were supposed to test our turbines by putting it 50 cm away, measured by the rotor, of a 4 m/s box fan. Then we had to turn the fan on, hook our turbine up to a multi-meter and then record how much voltage and how much current the spinning turbine generated. The following is chart depicting those results.
The winning team was Jake and Sonny with 0.089356 Watts of Electrical Power. My team, SEFA, came in a close second with 0.0787 Watts of Electrical Power.
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