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RCCSTAP Wind Turbine Competition
Transcript of RCCSTAP Wind Turbine Competition
Super Team Awesome People Wind Turbine Competition 2013 Dominic Dighera
Nate Fuentes Research Testing Final Build Problem Statement: For human development to continue, we must conduct research to find renewable sources of energy. Fossil fuels are a limited resource and eventually, coal and natural gas supplies will be depleted. Energy conversion methods that do not harm earth's ecosystem will become necessary. Energy is a global commodity of more and more demand. Industrialized countries, as well as countries beginning to industrialize, will continue to utilize more and more energy.
Through out this project, we conducted research, testing, and building with the goal of creating the most efficient wind turbine design to generate electricity with the least amount of expenditures. Wind Turbine Watts Govenor Venturi The earliest use of wind power: sail boats 5000-3200 BC 12th-19th Century Persians created windmills for water pumping and grain grinding 200 BC First wind turbine used to generate electricity. 1888 By the 1930s, wind generators for electricity were common on farms in the United States. 20th Century Wind power in California produces about 1.5% of the state's total electricity. Today Created out of a trash can with an oscillating fan zip-tied to the rear end of it; guaranteed a steady, consistent flow of air to test turbine and allowed us to analyze air foils without the inconsistencies of gusting natural wind. Three air foils and nine inch blades The Test Turbine Thus, reducing as many inconsistencies in the test data as possible, allowing us to effectively choose the proper air foil shape. Speed (in km/h) was measured by a bicycle speedometer Outfitted with dove tail blade mounts to enable swapping of blades with different air foil shapes without making an entirely new test turbine. DU vs NACA Building The Venturi Building the Gear Box Fabricating/Skinning the Blades Cost Analysis* DU 93-W-210 "The Sexy One" Testing.... Generators Wind Tunnel First, we were provided four generators to choose from.
For testing purposes, we mounted them to a drill and a multi-meter to measure the current and voltage, then calculated power. Airfoils are fundamentally important to design and efficiency. Building the Watts Governor Brief Historical Background Wind power conversion has been around for thousands of years.
The wind turbine has been reinvented hundreds to times. Invented by the ancient egyptians.
Also used by the Romans.
For transportation purposes. Incorporated vertical sails (blades moving around a central post). Later, transported to China around 1219 AD Developed throughout Western Europe Horizontal axis configuration.
Higher structural efficiency. Around 1390, the Dutch set out to refine the windmill. Big towers and wooden blades became became a Dutch symbol.
The United States developed small, steel bladed windmills Also used to pump water... Invented by Charles F. Brush in Cleveland, Ohio. 17 meters, 144 blades Operated for 20 years and eventually abandoned. Also, incorporated a "step up" gear box with a ratio of 50:1 The Final Design The venturi, wings, gearbox, center hub are made almost entirely out of plywood. -Cheap, easy to acquire, and inherently strong when layered together. We chose to use generator #1 because it produced the most voltage and, consequently, the most power. We tested three distinct air foil shapes. Constructed out of balsa wood. With nine inch blades.. In case you are unfamiliar, DU airfoils have been designed by the Delft University of Technology in the Netherlands. NACA airfoils were developed by the National Advisory Committee for Aeronautics. Scientists at DUT tested NACA air foils and discovered that the "thicker members suffered from severe degradation of performance due to premature transition". DU-yy-W-xxx Delft University The last two digits of the year in which the airfoil was designed. Denotes wind energy application. Denotes three times the airfoil maximum thickness in percentage of the chord. Angle of Attack Smaller angles (0-10) yielded no movement. Greater angles (10-15) yielded a faster overall speed, but were slow to start up. The steepest angles we tested (20-25) yielded a quicker start up, but a slower overall speed. Supported our theory to use a watts governor, which would vary the pitch of the blades according to the speed of the blades. We could favor a start up time and then feather into a faster angle of attack. Yielded the best results in terms of speed. We decided to test it with the venturi. The venturi seemed to produce an average increase of 61.8% in speed, as opposed to without the venturi. The data supported our decision to utilize a venturi. -Any defect in one layer is compensated by another layer. Hollow, very light weight Building was very tedious, but overall not complex. One challenge was getting the dowels to curve to form a circle. And waiting for the glue to set. Creating the shape of the fins Skinning The Venturi Time consuming Use of Monokote, a plastic shrink wrap film that adheres to surfaces with the use of heat. This film created the most aerodynamic finish we could find. It is smooth, light weight, and requires no after treatment, as opposed to other methods (such as paper-mache or cloth) which would require several applications, be even more time consuming, and produce rough/inconsistent finishes. Not particularly emphasized for this project, but a mechanical necessity. Our preliminary design for the gear box had a ratio of 67.3:1
Unfortunately, our final design had to forgo the use of a pulley. We imagined the "v-belt" would have started slipping, causing unforeseen problems.
This reduced our gear ratio to 20:1. We also chose to utilize ball bearings, instead of sleeve bearings or no bearings. Challenge:
Gears had excess overlapping- causing drive gears to come in contact with driven gear. They were rubbing too hard on each other, causing an improper pressure angle of gears, mashing them out of their ideal diameter. How we overcame the challenge:
By shimming the generator mount (tilting it away) Challenge:
Linkage alignment was tricky. How we overcame the challenge:
Modified shaft design to have a flexible section. Complex design Most designs only have two arms, whereas we needed three arms because, with three blades, we would have uneven forces otherwise. Also, most governors are mounted vertically. Since our design is mounted horizontally, we lost the force of gravity. We had to overcome this problem by finding the right springs. Our lack of machinery (such as a lathe) did not deter us from moving forward with our design. We had to construct innovative ways of building. Hollow, light weight, skinned with Monokote Root Mid Tip Base of rotor tends to be thicker; aerodynamics not as critical because it supports the rest of the blade. Center of blade rotates at a slower speed. As you progress, the blade narrows to a more efficient air foils shape, culminating into a high speed airfoil at the tip. Tip is important to reduce noise pollution and drag. It also had a sharper angle of attack to move faster. 18 inch blades The prototype only had two cross sections. No real challenges in building. Perfecting size/thickness was tricky. Final Project Theoretical Wind Power: S= the cross sectional area of the turbine, in terms of radius r. Our blades are 18 inches long (0.45 m) rho= 1.225 kg/m^3 air density V= 3.2 m/s, wind velocity Theoretical Rotor Power A= cross sectional area of the turbine, in terms of radius r. Our blades are 18 inches long (0.45 m) rho, 1.225 kg/m^3, air density V=3.2 m/s, wind velocity Cp= 0.59, theoretical maximum power efficiency, according to Betz law. A wind turbine is a device that converts kinetic wind energy to some form of mechanical energy. The mechanical energy can then be stored as electricity, momentum, or it can be utilized. Widespread use of individual wind generators competed against fossil fuel plants and centrally-generated electricity Use also declined with the invention of the steam engine. Renewed interest in alternative energy sources during the oil shortages of the 1970's. Produced 12 kW. Wind energy projects totaling about 5,549 megawatts of capacity are operating in California today, providing enough electricity to power more than 2 million California households. Designed by James Watt in 1788 How it works How we utilized it. Also called "centrifugal governor" or "fly ball governor" Possible improvements to the current design for the future: Nylon spacers/bushings (instead of electrical tape)
Threaded pipe (instead of rod) in order to reduce mass.
Smooth out threads on all rubbing surfaces
Remove all non-structural mass
Engine Oil to lubricate parts
Construct a better wind tunnel
Order skin online (instead of retail price) to reduce to cost
Experiment with different combos of air foils
Experiment with wing tip design Ball bearings (set of 8)..... $9.95
Monokote Aluminum 25'........ $56.69
Monokote Aluminum 6'......... $14.99
Monokote Blue 6'............. $14.99
Brass strap 12".............. $1.09
Hex nut 4-40 (set of 8)...... $0.99
Socket head screw 4-40 (12).. $3.27
Flat Washer (set of 16)...... $1.70
Set screw 3/8-16............. $1.04
3/8" coupling nut............ $3.12
Bronze flange bearing (2).... $2.92
Allthread rod 3/8-16......... $1.37
Total........................ $111.13 *tooling not included Tools used: belt sander, band saw, table saw, drill press, handheld/cordless/corded drills, impact driver, router, dremel, hand saw, pull saw, tap and die set, hand drill, shoulder vice, coping saw, jig saw, various wrenches, sockets, etc, (STANDARD WOOD WORKING GARAGE) In search for the "almost perfect engine" Used on water wheels, water driven turbines, steam engines, wind mills, internal combustion engines, variously fueled turbines, and some modern striking clocks.. Controls the speed of an engine by regulating the amount of fuel admitted. As the governor rotates, the spherical weights tend to fly outward under centripetal force; thus, the more quickly the governed device operates, the further outwards the weights will travel. We took the same principals used in a Watts Governor, but instead of it regulating fuel, it regulates the pitch of the turbine blades. The Venturi Effect How it works How we utilized it. Named after an italian physicist, Giovanni Battista Venturi Used in grills, gas stoves, Bunsen burners, perfume atomizer, carburetors, scuba diving regulators... The Dyson Air Multiplier, a fan with no blades! As the air moves into the the throat of the venturi, the wind speed increase because of a pressure differential, creating flow. Our Venturi creates a high pressure area just before the turbine blades, then quickly changes to a low pressure area. This sudden change in pressure accelerates the air as it reaches the turbine blades.