Today our group came to terms with a pencil sharpener. With the goal of finding a well suited motor for our new project, where we create our own design for a wind turbine, we would use this motor as a generator. Even though the pencil systems motor doesn’t seem to be the right fit, we learned about how one of these motors can run a machine. We learned how the wires connected and how a circuit was created to allow multiple components of the machine to work together with the right timing. Most importantly some experience with the magnets and motors. Im excited for the potential in this project.
Through the process of building our wind power kit, we dealt with and learned first hand about the concepts of gears, the Bernoulli effect, and the generators function of transforming kinetic energy into electrical energy.
In creating our wind turbines gear box we had to learn the function that gears play in the system and what using different combinations of them can accomplish. Gears provide mechanical advantage to a system. There are all different sizes of gears that fit together with each other. By using different combinations of these gears, you can adapt a machine to different conditions. A bike is a great example of this that helped me understand the concept. Say you are trying to pedal up a big hill, you want as much mechanical advantage as you can get. So you would want a smaller input gear and a larger output gear, these two gears rotate at different rates giving you a gear ratio. The input gear is connected to the power source, in this case your legs, while the output gear is connected to the back wheel. Well say this input gear had only 10 teeth, while the output gear had 30 teeth. The input gear would then be making three rotations for every one rotation of the output. This would make the pedalling much easier because it spreads out the amount of force you have to put in to make one rotation of the wheel, giving you more power, but less speed.
This is what our gear box looked like, it is a parallel system with a shaft running from the turbine (input) and the shaft below that runs to the generator (output). In this picture the small input gear is matched with the large output gear, which makes it easier to spin the turbine, as it would be easier to pedal, and therefore optimal for lighter winds, but it cranks on the generator less creating less electricity. The LED light we have hooked up to the generator barely lights up in this gear.
In this gear which is a 1:1 ratio, this combination had the right balance it could be blown by the fan and still power up the light.This was our last combination with a large input gear and a small output gear. This made the propellers more difficult to spin so that it could only be spun by hand, but when you did, the generator would make a whining sound and the LED would be brightly lit.
This type of gear ratio would be ideal in heavier winds to create the most electricity possible. Just as it would on a bike going downhill to gain more speed.
The Bernoulli effect is another concept that was played out in our kit. It has to do with the shape of the propellers which are also very similar to the shape of the wings on an airplane. It is also the same principle on which sail boats are pulled along into the wind. It has to do with creating low pressures and high pressures in the air around the wing, propeller or sail. In the example of a plane, the shape of the bottom of the wing is more streamlined creating a faster way for the air to travel rather than over the curve and down the topside of the wing. The faster moving air below the wings create higher pressures which you can imagine push up on the wing adding to the force of the lift. While the slower moving air is relatively low pressure providing an easier pathway to fly through, pulling the wings upwards. The reason the propellers on modern wind mills has this shape is so that the turbine can rotate more efficiently.
The last thing we are going to look at is how the generator transforms kinetic energy, in the form of a rotating turbine, to electrical energy, in the form of the LED light. The way it does this is use the kinetic energy to spin a magnet around a coil of wire. What this accomplishes is that the magnetic field created pushes electrons through the wire. It applies a pressure and moves the electrons along much like a pump pushes water through a pipe. Once the electrons are flowing through the wire we have electricity at varying volts and amps. This can be connected to anything as we know in our very diverse use of electricity in technology. Our kit can even charge batteries which transforms the energy again, this time from electrical energy to chemical energy stored in the battery.
The hands on experience of this project really helped our group come to terms with these concepts that play a large role in technology that is helping protect our climates future.
First day opening our kit I was not there, but when coming back I’ve noticed we’ve got a lot of work to do understanding gears and their mechanics. They got a good head start on the gear box though, it will stand on top of the beam, behind the propellers along with our motor. As we worked on it today we added the motor and the LED light and getting ready to attach it to the base.
This blog will be discussing climate sciences and learning about engineering to overcome some of the challenges our climate is facing. Also a new addition of topics relating to global water issues, discussing current events and following trends and affects.