File Name: design and development of a vertical axis micro wind turbine .zip
Travis J. Carrigan, Brian H.
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A wind turbine , or wind energy converter , is a device that converts the wind's kinetic energy into electrical energy. Wind turbines are manufactured in a wide range of sizes, with either horizontal or vertical axes. There are Gigawatt in hundreds of thousands of large turbines , known as wind farms , with 60 GW added per year.
One assessment claimed that, as of [update] , wind had the "lowest relative greenhouse gas emissions, the least water consumption demands and Larger turbines can be used for making contributions to a domestic power supply while selling unused power back to the utility supplier via the electrical grid.
The windwheel of Hero of Alexandria 10 AD — 70 AD marks one of the first recorded instances of wind powering a machine in history. These " Panemone " were vertical axle windmills, which had long vertical drive shafts with rectangular blades. Wind power first appeared in Europe during the Middle Ages. The first historical records of their use in England date to the 11th or 12th centuries, there are reports of German crusaders taking their windmill-making skills to Syria around Advanced wind turbines were described by Croatian inventor Fausto Veranzio.
In his book Machinae Novae he described vertical axis wind turbines with curved or V-shaped blades. The first electricity-generating wind turbine was a battery charging machine installed in July by Scottish academic James Blyth to light his holiday home in Marykirk , Scotland.
Brush was able to build the first automatically operated wind turbine after consulting local University professors and colleagues Jacob S. Gibbs and Brinsley Coleberd and successfully getting the blueprints peer-reviewed for electricity production in Cleveland, Ohio. In Denmark by , there were about windmills for mechanical loads such as pumps and mills, producing an estimated combined peak power of about 30 MW.
Around the time of World War I, American windmill makers were producing , farm windmills each year, mostly for water-pumping. By the s, wind generators for electricity were common on farms, mostly in the United States where distribution systems had not yet been installed. In this period, high-tensile steel was cheap, and the generators were placed atop prefabricated open steel lattice towers.
It was reported to have an annual capacity factor of 32 percent, not much different from current wind machines. In the autumn of , the first megawatt-class wind turbine was synchronized to a utility grid in Vermont. The Smith—Putnam wind turbine only ran for 1, hours before suffering a critical failure.
The unit was not repaired, because of a shortage of materials during the war. Despite these diverse developments, developments in fossil fuel systems almost entirely eliminated any wind turbine systems larger than supermicro size. In the early s, however, anti-nuclear protests in Denmark spurred artisan mechanics to develop microturbines of 22 kW. Organizing owners into associations and co-operatives lead to the lobbying of the government and utilities and provided incentives for larger turbines throughout the s and later.
Local activists in Germany, nascent turbine manufacturers in Spain, and large investors in the United States in the early s then lobbied for policies that stimulated the industry in those countries. It has been argued that expanding use of wind power will lead to increasing geopolitical competition over critical materials for wind turbines such as rare earth elements neodymium, praseodymium, and dysprosium.
But this perspective has been criticised for failing to recognise that most wind turbines do not use permanent magnets and for underestimating the power of economic incentives for expanded production of these minerals.
It is the mean annual power available per square meter of swept area of a turbine, and is calculated for different heights above ground. Calculation of wind power density includes the effect of wind velocity and air density. Wind turbines are classified by the wind speed they are designed for, from class I to class III, with A to C referring to the turbulence intensity of the wind. Conservation of mass requires that the amount of air entering and exiting a turbine must be equal.
If the effective area of the disk is A, and the wind velocity v, the maximum theoretical power output P is:.
Wind-to-rotor efficiency including rotor blade friction and drag are among the factors affecting the final price of wind power. To protect components from undue wear, extracted power is held constant above the rated operating speed as theoretical power increases at the cube of wind speed, further reducing theoretical efficiency.
Efficiency can decrease slightly over time, one of the main reasons being dust and insect carcasses on the blades which alters the aerodynamic profile and essentially reduces the lift to drag ratio of the airfoil.
Analysis of wind turbines older than 10 years in Denmark showed that half of the turbines had no decrease, while the other half saw a production decrease of 1. This is due to a faster recovery wake and greater flow entrainment that occur in conditions of higher atmospheric stability. However, wind turbine wakes have been found to recover faster under unstable atmospheric conditions as opposed to a stable environment.
Different materials have been found to have varying effects on the efficiency of wind turbines. When tested, the results showed that the materials with higher overall masses had a greater friction moment and thus a lower power coefficient. Wind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common. Large three-bladed horizontal-axis wind turbines HAWT with the blades upwind of the tower produce the overwhelming majority of wind power in the world today.
These turbines have the main rotor shaft and electrical generator at the top of a tower, and must be pointed into the wind. Small turbines are pointed by a simple wind vane , while large turbines generally use a wind sensor coupled with a yaw system. Most have a gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator. These don't need a gearbox and are called direct-drive, meaning they couple the rotor directly to the generator with no gearbox in between.
While permanent magnet direct-drive generators can be more costly due to the rare earth materials required, these gearless turbines are sometimes preferred over gearbox generators because they "eliminate the gear-speed increaser, which is susceptible to significant accumulated fatigue torque loading, related reliability issues, and maintenance costs.
Most horizontal axis turbines have their rotors upwind of the supporting tower. Downwind machines have been built, because they don't need an additional mechanism for keeping them in line with the wind. In high winds, the blades can also be allowed to bend, which reduces their swept area and thus their wind resistance. Despite these advantages, upwind designs are preferred, because the change in loading from the wind as each blade passes behind the supporting tower can cause damage to the turbine.
Turbines used in wind farms for commercial production of electric power are usually three-bladed. These have low torque ripple , which contributes to good reliability. The size and height of turbines increase year by year. Designs with 10 to 12 MW are in preparation. Vertical-axis wind turbines or VAWTs have the main rotor shaft arranged vertically. One advantage of this arrangement is that the turbine does not need to be pointed into the wind to be effective, which is an advantage on a site where the wind direction is highly variable.
It is also an advantage when the turbine is integrated into a building because it is inherently less steerable. Also, the generator and gearbox can be placed near the ground, using a direct drive from the rotor assembly to the ground-based gearbox, improving accessibility for maintenance.
However, these designs produce much less energy averaged over time, which is a major drawback. Vertical turbine designs have much lower efficiency than standard horizontal designs.
When a turbine is mounted on a rooftop the building generally redirects wind over the roof and this can double the wind speed at the turbine. While wind speeds within the built environment are generally much lower than at exposed rural sites,   noise may be a concern and an existing structure may not adequately resist the additional stress.
They also generally require some external power source, or an additional Savonius rotor to start turning, because the starting torque is very low. The torque ripple is reduced by using three or more blades, which results in greater solidity of the rotor. Solidity is measured by blade area divided by the rotor area. Newer Darrieus type turbines are not held up by guy-wires but have an external superstructure connected to the top bearing.
A subtype of Darrieus turbine with straight, as opposed to curved, blades. The cycloturbine variety has variable pitch to reduce the torque pulsation and is self-starting.
Straight, V, or curved blades may be used. These are drag-type devices with two or more scoops that are used in anemometers, Flettner vents commonly seen on bus and van roofs , and in some high-reliability low-efficiency power turbines.
They are always self-starting if there are at least three scoops. Twisted Savonius is a modified savonius, with long helical scoops to provide smooth torque. This is often used as a rooftop wind turbine and has even been adapted for ships. The parallel turbine is similar to the crossflow fan or centrifugal fan. It uses the ground effect.
Vertical axis turbines of this type have been tried for many years: a unit producing 10 kW was built by Israeli wind pioneer Bruce Brill in the s. Wind turbines convert wind energy to electrical energy for distribution. Conventional horizontal axis turbines can be divided into three components:. Due to data transmission problems, structural health monitoring of wind turbines is usually performed using several accelerometers and strain gages attached to the nacelle to monitor the gearbox and equipment.
Currently, digital image correlation and stereophotogrammetry are used to measure dynamics of wind turbine blades. These methods usually measure displacement and strain to identify location of defects. Dynamic characteristics of non-rotating wind turbines have been measured using digital image correlation and photogrammetry. Wind turbine rotor blades are being made longer to increase efficiency.
This requires them to be stiff, strong, light and resistant to fatigue. Companies seek ways to draw greater efficiency from their designs.
A predominant way has been to increase blade length and thus rotor diameter. Retrofitting existing turbines with larger blades reduces the work and risks of redesigning the system. Longer blades need to be stiffer to avoid deflection, which requires materials with higher stiffness-to-weight ratio.
Because the blades need to function over a million load cycles over a period of 20—25 years, the fatigue of the blade materials is also critical. The stiffness of composites is determined by the stiffness of fibers and their volume content. Typically, E-glass fibers are used as main reinforcement in the composites. This increases the stiffness, tensile and compression strength. A promising composite material is glass fiber with modified compositions like S-glass, R-glass etc. Carbon fiber has more tensile strength, higher stiffness and lower density than glass fiber.
An ideal candidate for these properties is the spar cap, a structural element of a blade which experiences high tensile loading. Instead of making wind turbine blade reinforcements from pure glass or pure carbon, hybrid designs trade weight for cost. More research is needed about the optimal composition of materials .
Design of a Vertical-Axis Wind Turbine
Since the focus on the energy crisis and environmental issues due to excessive fossil fuel consumption, wind power has been considered as an important renewable energy source. Recently, several megawatt-class large-scale wind turbine systems have been developed in some countries. Even though the large-scale wind turbine can effectively produce electrical power, the small-scale wind turbine has been continuously developed due to some advantages; for instance, it can be easily built at a low cost without any limitation of location, i. In case of small-scale wind turbines, the vertical axis wind turbine VAWT is used in the city despite having a lower efficiency than the horizontal axis wind turbine. This aim of this work is to design a high-efficiency W class composite VAWT blade that is applicable to relatively low-speed regions.
A wind turbine , or wind energy converter , is a device that converts the wind's kinetic energy into electrical energy. Wind turbines are manufactured in a wide range of sizes, with either horizontal or vertical axes. There are Gigawatt in hundreds of thousands of large turbines , known as wind farms , with 60 GW added per year. One assessment claimed that, as of [update] , wind had the "lowest relative greenhouse gas emissions, the least water consumption demands and Larger turbines can be used for making contributions to a domestic power supply while selling unused power back to the utility supplier via the electrical grid. The windwheel of Hero of Alexandria 10 AD — 70 AD marks one of the first recorded instances of wind powering a machine in history. These " Panemone " were vertical axle windmills, which had long vertical drive shafts with rectangular blades.
Darrieus-type vertical axis rotary-wings with a new design approach grounded in double-multiple streamtube performance prediction model[J]. AIMS Energy, , 6 5 : Article views PDF downloads Cited by 4. AIMS Energy , , 6 5 : Previous Article Next Article.
PDF | Wind energy is the kinetic energy associated with movement of large masses of air. Vertical Axis wind power generators, represent a very promising the wind. Small turbines are pointed by a simple wind vane, while.
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