magnetic levitating wind turbine -...
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Magnetic Levitating Wind Turbine Department of Mechanical & Industrial Engineering, TAMUK
Faculty Mentor: Dr. Butterworth Students: Daniel Chapa, Davey Dockens,
Kerynn Rivier, Chris Srubar
Abstract
Green energy has been an important area of interest for research in the energy sector. Rising electricity costs has created an opportunity for our first semester design team to develop a wind turbine that will act as a renewable power source for personal use, easing the burden on one’s pocket over time. Problems with current designs, such as noise and size factors, often don’t allow them to be used in a residential setting. Through the design process, we expect to address some of these problems with solutions developed through practical engineering knowledge and the design process. This will include but not be limited to: brainstorming, conceptualization, design studies, detailed design, critical design reviews, fabrication and testing. The project will incorporate numerous engineering disciplines such as fluid mechanics, strength of materials, manufacturing, and finite element analysis among others. First and foremost we began by establishing clear objectives for the project.
• Design a wind turbine for residential use, specifically geared towards households in the city.
• Reduce the number of moving parts to decrease noise pollution.
• Safe for wildlife and people to be around and maintain.
Corpus Christi Wind Data
Blades Design
Wind Power Analysis
Future Work
Power Distributed to the Rotor Velocity of wind, V (Mph) 3 6 9 12 15 18 21 24 Power wind, P (Watts) 1.692 13.53 45.67 108.3 211.4 365.4 580.2 866.1 Max Power (Watts) 1.002 8.019 27.06 64.15 125.3 216.5 343.8 513.2 Power with Cp of .35, (watts) 0.592 4.736 15.98 37.89 74 127.9 203.1 303.1
The power analysis is a critical aspect of the design process. It has been necessary in order to accurately model the power we expect the wind turbine to produce.
Because the wind power is dependent on 𝑃 = 1
2𝜌𝐴𝑣3; where
𝜌 is the density of air, A is the swept area of the blades, and 𝑣 the wind velocity. Simple averages of daily or monthly wind speeds will provide an inaccurate model of the power that can be obtained from the wind. In order to provide accurate models of the expected power output, we began by uploading data from the NOAA website, based on wind speed in Corpus Christi on the hour for every hour of the 2010 year. A distribution curve was generated to plot the number of hours (frequency) vs. the wind speed within a certain range. The chart below shows the frequency distribution for 2010.
Conceptual Model
The power distributed to the rotor can be calculated with Protor = Cp * Pwind where Cp
is the power coefficient. The maximum power the can be converted to the blades would be when Cp = .59. We are approximating our generator to operate with a power coefficient ≈ .35.
However the shroud over the blades has the potential to increase the power coefficient.
The wind generator is still in the conceptual design process. With the set objectives and parameters the group has come up with a basic model of the wind turbine. The blades would have a ring that will hold the magnets and the outer shroud would hold the coils. The group is currently researching if the blade can be levitated to reduce friction and wear.
Parameters • 4 ft blade diameter • Levitating blade with use of
magnetic track • Approximately 80 lbs • Design operating at 35%
efficiency • 3 MPH cut-in speed • 40 MPH cut-off speed
λ, ω, and v calculations at Increasing number of blades at a 12mph and 2’Radius wind velocity
Number of blades, n 1 2 3 4 5 6 7 8 9 10
Tip speed ratio, λ 12.6 6.3 4.2 3.1 2.5 2.1 1.8 1.6 1.4 1.3
Angular velocity, ω (rad/s) 110.6 55.3 36.9 27.6 22.1 18.4 15.8 13.8 12.3 11.1
tip speed, v (ft/s) 221.2 110.6 73.7 55.3 44.2 36.9 31.6 27.6 24.6 22.1
The team is currently working on a spread sheet to determine the number of blades to operate within the set parameters. The more blades the generator has the slower the tip speed would be and therefore decreasing the power coefficient. If there are not enough blades then it could affect start up speed of the generator. To determine the number of blades the following equation would be used. The optimal tip speed ratio (λopt) can be
calculated for different amount of blades by using λ𝑜𝑝𝑡
=4𝜋
𝑛
where n is the number of blades. With the optimal tip speed ratio we can find the optimal angular velocity
𝜔𝑜𝑝𝑡 = λ𝑜𝑝𝑡
𝑉
𝑅 where V is the wind velocity and R is the
radius of the rotor at the tip equal to 2’ in this design. The tip speed (vtip) could then be calculated by 𝑣𝑡𝑖𝑝 = 𝜔𝑅.
The blades would be designed with an angle of twist to transfer the maximum power to the blades. The angle of twist would be determined from the wind analysis and the following calculations. Relative Wind Velocity = 𝑉𝑟𝑒𝑙
𝑉𝑟𝑒𝑙 = 𝜔𝑟 2 + 𝑉2
• r = radius at any point on the blade
Flow Angle = 𝛷
𝛷 = tan−1 𝑉
𝜔𝑟
Angle of Attack 𝛼 Normally Between 1-15
Degrees Twist Angle = 𝜃
𝜃 = 𝛷 − 𝛼
Special Thanks
Dr. Butterworth Dr. Chen -Coil Design -Wind Analysis
0
500
1000
1500
2000
2500
3000
3500
4000
0 5 10 15 20 25 30 35 40
Po
we
r W
atts
Velocity of Wind (Mph)
Power Distribution 2’ Radius Blade
Power of Wind
Max Power Distributedto Blades Cp = .59
Power Transfer with Cp= .35
Conclusions
The design is a relatively new idea that requires continuing research in turbine design
Lack of information in Levitation brings uncertainty of the a levitating blade without experimental data
The group has gained valuable knowledge in the field of wind turbines
SolidWorks Model Blade
Twisted Blade
Air Foil
0
200
400
600
800
1000
1200
1400
1600
1800
0-3 3-6 6-9 9-12 12-15 15-18 18-21 21-24 24-27 27-30
hrs
MPH
Wind Speed Frequency: 2010
Frequency
Background
Many households are taking advantage of wind turbines to power homes and reduce one’s electricity bill, however current designs are limiting one’s ability to possess such a device for personal use. Noise pollution, wildlife impact, and aesthetics have led cities to ban certain designs for residential use.
Electrical Generation
The coils would need to be designed so they could be attached to the shroud. The magnets would need to be sized to be attached to the cylinder that would rotate with the blades. With the coils on the outside of the rotor the change in flux would be a function of the tip speed of the rotor. The alternating current would be as shown in the figure.
Power Calculations
• Current =𝐼 =𝑵𝑩𝑳
𝒅𝒙
𝒅𝒕
𝑅=
ℰ
𝑅
• Induced Electromagnetic Force =𝓔=𝑵𝑩𝑳𝒅𝒙
𝒅𝒕
• Resistance of Coils = 𝑅 = 𝜌𝐿
𝐴
• 𝜌 = resistivity of the wire
• L = Total length of wire in coil • A = Cross Sectional Area of the wire
•𝑑𝑥
𝑑𝑡 = Velocity of Magnets= Tip Speed of Blades
• Power = P = I*𝓔
Levitation Methods
The levitation design is still within experimental stages. Our team has developed a couple of options that may be feasible, but due to the fact that there are few resources available to compare our design to we are not able to choose a design at this time. Through experimentation we will determine which design will work best. After experimentation if our designs are not feasible we will research magnetic bearings, and will either purchase or create a design of our own.
Option 1: 4 Rows-Small Neodymium
Magnet
Pros Cons
Cheaper than
option 2
Less weight
No wearing parts
Frictionless
May cause excess
vibration
Lack of
information on
levitation
Option 2: 8 Rows-Small Neodymium
Magnet
Pros Cons
Frictionless
No wearing parts
Expensive
Adds weight
May cause excess
vibration
Lack of
information on
levitation
The levitation design is still within experimental stages. Our team has developed a couple of options that may be feasible, but due to the fact that there are few resources available, we are devoting substantial time in researching specifics of the design. Through experimentation we will determine which design will work best. After experimentation if our designs are not feasible we will research magnetic bearings, and will either purchase or create a design of our own.