The use of alternative energy sources is one of the main trends of our time. Clean and affordable wind energy can be converted into electricity even in your home, if you build a wind turbine and connect it to a generator.
You can build blades for a wind generator with your own hands from ordinary materials, without using special equipment. We will tell you what form of blades are more efficient and help you find the right drawing for a wind power plant.
The content of the article:
- How does a simple wind generator work?
- What is the best shape of the blade?
What do the blades do at home?
- PVC Sewer Pipe
- Aluminum - thin, light and expensive
- Fiberglass or fiberglass - for professionals
- Cheap and cheerful: wooden detail for the wind wheel
- Drawings and examples of blades
- Perform balancing windmill
- Conclusions and useful video on the topic
How does a simple wind generator work?
Wind generator - a device that allows you to convert wind energy into electricity.
The principle of its operation lies in the fact that the wind rotates the blades, drives the shaft, through which the rotation enters the generator through a gearbox, which increases speed.
The work of the wind power plant is estimated by KIEV - the utilization of wind energy. When the wind wheel spins quickly, it interacts with a lot of wind, which means it takes more energy from it.
Two main types of wind generators are divided:
Vertically oriented models are built so that the axis of the propeller is perpendicular to the ground. Thus, any movement of air masses, regardless of direction, sets the structure in motion.
Such versatility is a plus of this type of wind turbine, but they lose to horizontal models in terms of productivity and operating efficiency.
A horizontal wind generator resembles a weather vane. To rotate the blades, the design must be rotated in the right direction, depending on the direction of air movement.
To control and catch changes in wind direction, install special devices. The efficiency with this arrangement of the screw is much higher than with the vertical orientation. In domestic use it is more rational to use wind generators of this type.
What is the best shape of the blade?
One of the main elements of a wind generator is a set of blades.
There are a number of factors associated with these details that affect the efficiency of a windmill:
- the size;
- the form;
If you decide to design the blades for an improvised windmill, be sure to consider all these parameters. Some believe that the more wings on the generator screw, the more wind energy can be obtained. In other words, the more the better.
However, this is not the case. Each individual part moves, overcoming air resistance. Thus, a large number of blades on the screw requires more wind power to make one turn.
In addition, too many wide wings can cause the formation of the so-called "air cap" in front of the propeller, when the air flow does not pass through the windmill, but bends around it.
The form is of great importance. It depends on the speed of the screw. Poor wrap causes whirlwinds that inhibit the wind wheel
The most effective is a single-blade wind turbine. But to build and balance it with your own hands is very difficult. The design is unreliable, albeit with a high efficiency. According to the experience of many users and manufacturers of wind turbines, the most optimal model is a three-bladed.
The weight of the blade depends on its size and the material from which it will be made. The size needs to be selected carefully, being guided by formulas for calculations. Edges are better treated so that on one side there is a rounding, and the opposite side is sharp
The correct form of the blade for the wind generator is the foundation of its good work.
For home making, these options are suitable:
- sailing type;
- wing type.
The blades of a sailing type are simple broad bands, like in a windmill. This model is the most obvious and easy to manufacture. However, its efficiency is so low that this form is practically not used in modern wind turbines. The efficiency in this case is about 10-12%.
A much more efficient form is the blades of the wing profile. It involved the principles of aerodynamics, which take to the air huge aircraft. A screw of this shape is more easily driven and rotates faster. Air flow dramatically reduces the resistance that a windmill encounters on its way.
The correct profile should resemble an airplane wing. On the one hand, the blade has a thickening, and on the other - a gentle descent. Air masses flow around a piece of this shape very smoothly.
The efficiency of this model reaches 30-35%. The good news is that you can build a wing blade with your own hands using a minimum of tools. All basic calculations and drawings can be easily adapted to your windmill and use free and clean wind energy without restrictions.
What do the blades do at home?
Materials that are suitable for building a wind generator are, above all, plastic, light metals, wood and a modern solution - fiberglass. The main question is how much work and time you are willing to spend on making a windmill.
PVC Sewer Pipe
The most popular and widely used material for the manufacture of plastic blades for a wind generator is an ordinary PVC sewer pipe. For most household generators with a screw diameter of up to 2 m, a pipe of 160 mm will suffice.
The advantages of this method include:
- low price;
- availability in any region;
- simplicity of work;
- A large number of schemes and drawings on the Internet, a great experience.
Pipes are different. This is known not only to those who manufacture improvised wind power plants, but to everyone who has encountered the installation of a sewage system or water mains. They differ in thickness, composition, manufacturer. The pipe is inexpensive, so do not try to further reduce the cost of your windmill, saving on PVC pipes.
Poor plastic pipe material may cause blades to crack during the first test and all work will be done in vain.
First you need to decide on the pattern. There are many options, each form has its own advantages and disadvantages. It may make sense to experiment first before cutting out the final version.
Since the price of pipes is low, and you can find them in any hardware store, this material is perfect for the first steps in modeling the blades. If something goes wrong, you can always buy another pipe and try it first, the wallet will not suffer much from such experiments.
Experienced wind power users have noticed that it is better to use orange rather than gray pipes for making blades for a wind generator. They keep their shape better, do not bend after the formation of the wing and last longer
Amateur designers prefer PVC, because during testing a broken blade can be replaced with a new one, made in 15 minutes right on the spot with a suitable piece. Simple and fast, and most importantly - available.
Aluminum - thin, light and expensive
Aluminum is lightweight and durable metal. It is traditionally used for the manufacture of blades for wind turbines. Due to the low weight, if you give the plate the desired shape, the aerodynamic properties of the screw will be at its height.
The main load experienced by the windmill during rotation, is aimed at bending and rupture of the blade. If the plastic during such work quickly cracks and fails, you can count on an aluminum screw for much longer.
However, if you compare aluminum and PVC pipes, metal plates will still be heavier. At high speeds, the risk of damaging the blade itself and the screw at the attachment point is great.
Another disadvantage of aluminum parts is the complexity of manufacturing. If the PVC pipe has a bend, which will be used to impart aerodynamic properties of the blade, then aluminum, as a rule, is taken in the form of a sheet.
After cutting the parts according to the template, which is in itself much more difficult than working with plastic, the resulting billet will still need to be rolled and given the correct bend. At home and without a tool to do it will not be so easy.
Fiberglass or fiberglass - for professionals
If you decide to approach the issue of creating a blade consciously and are ready to spend on it a lot of strength and nerves, fiberglass will do. If you have not previously dealt with wind turbines, to begin acquaintance with the simulation of a fiberglass windmill is not the best idea. Still, this process requires experience and practical skills.
The blade of several layers of fiberglass, bonded with epoxy glue, will be durable, lightweight and reliable. With a large surface area, the detail turns out to be hollow and almost weightless.
For the manufacture of fiberglass is taken - a thin and durable material that is available in rolls. In addition to fiberglass, epoxy glue is useful for fixing layers.
Start by creating a matrix. This is such a blank, which is a form for future details.
The matrix can be made of wood: timber, board or log. Straight from the array cut down the volumetric silhouette of the half blade. Another option - a form of plastic
It is very difficult to make a blank yourself; you need to have a finished model of a blade made of wood or other material before your eyes, and only then the matrix for the part is cut out using this model. Such matrices need at least 2. But, having made a successful form once, it can be used many times and erected in this way more than one windmill.
The bottom of the form is carefully greased with wax. This is done so that the finished blade can be easily removed later. Lay a layer of fiberglass, coat it with epoxy glue. The process is repeated several times until the workpiece reaches the desired thickness.
Then the glue should dry. Some recommend placing the form in a vacuum bag and pumping out air. So it is better for glue to penetrate all layers of fiberglass, leaving no untreated areas.
When the epoxy glue dries, half of the parts are carefully removed from the die. The same is done with the second half. The parts are glued together to make a hollow volumetric part. Lightweight, durable, proper aerodynamic shape fiberglass blade - the pinnacle of skill home fan of wind power plants.
Its main disadvantage is the complexity of the implementation of the idea and a large number of defects at first, until the ideal matrix is obtained, and the creation algorithm is not perfected.
Cheap and cheerful: wooden detail for the wind wheel
Wooden blade - grandfather's method, which is easy to implement, but ineffective with the current level of electricity consumption. The detail can be made from a solid board of light wood species, for example, pine. It is important to choose a well-dried wooden piece.
If the wood is damp, in the process of drying the screw can “lead” and it is deformed. Yes, and the weight of a wet tree is much higher than dry.
You need to choose a suitable shape, but take into account the fact that the wooden blade will not be a thin plate, like aluminum or plastic, but a three-dimensional construction. Therefore, to shape the workpiece is not enough, you need to understand the principles of aerodynamics and imagine the outlines of the blade in all three dimensions.
Give the final form of the tree will have a plane, better electro. For durability, wood is treated with an antiseptic protective varnish or paint.
The main drawback of this design is the large weight of the screw. To move this colossus off the ground, the wind must be strong enough that it is difficult in principle. However, wood is available material. Boards that are suitable for creating a wind turbine screw can be found right in your yard, without spending a penny. And this is the main advantage of wood in this case.
The efficiency of a wooden blade tends to zero. As a rule, the time and effort that goes into creating such a windmill are not worth the result, expressed in watts. However, as a training model or a trial copy of a wooden part is quite the place to be. And the weather vane with wooden blades looks spectacular on the site.
Drawings and examples of blades
It is very difficult to make the correct calculation of a wind generator screw, not knowing the basic parameters that are displayed in the formula, as well as not having a clue how these parameters affect the operation of a windmill.
It is better not to waste your time if there is no desire to delve into the basics of aerodynamics. Ready-made diagrams with given parameters will help you choose a suitable blade for a wind power plant.
Drawing blades for two-bladed propeller. It is made of sewer pipe 110 diameter. The diameter of the screw windmill in these calculations - 1 m
Such a small wind turbine will not be able to provide you with high power. Most likely, you can hardly squeeze more than 50 watts out of this design. However, a two-bladed screw made of lightweight and thin PVC pipe will give a high rotational speed and will ensure the operation of the windmill even with a slight wind.
Drawing of the blade for the three-bladed propeller of the wind generator from a pipe 160 mm in diameter. Estimated speed in this version - 5 with a wind of 5 m / s
A three-blade screw of this shape can be used for more powerful units, approximately 150 W at 12 V. The diameter of the entire screw in this model reaches 1.5 m. The wind wheel will rotate quickly and easily start to move. Three-winged wind turbines are most common in home power plants.
Drawing homemade blades for a 5-blade propeller wind turbine. It is made of PVC pipe with a diameter of 160 mm. Estimated speed - 4
Such a five-blade propeller will be able to issue up to 225 revolutions per minute at a design wind speed of 5 m / s. To build the blade according to the proposed drawings, you need to transfer the coordinates of each point from the "Front / rear piece coordinates" columns to the surface of the plastic sewer pipe.
According to the table below, you can calculate the diameter of the windmill with 2-16 blades. In this case, you can choose the size of the desired output power.
From the table it can be seen that the larger the wind turbine’s wings, the shorter their length should be to obtain a current of the same power.
As practice shows, it is quite difficult to maintain a wind generator larger than 2 meters in diameter. If, in accordance with the table, you need a larger wind turbine, think about increasing the number of blades.
With the rules and principles wind generator calculation will introduce the article, which describes the process of making calculations step by step.
Perform balancing windmill
Balancing wind turbine blades will help to make its work as efficient as possible. For the implementation of balancing you need to find a room where there is no wind or draft. Of course, for a wind wheel larger than 2 m in diameter, it will be difficult to find such a room.
The blades are assembled into the finished structure and installed in the working position. The axis should be strictly horizontally level. The plane in which the screw will rotate must be set vertically strictly, perpendicular to the axis and ground level.
A screw that does not move needs to be rotated 360 / x degrees, where x = the number of blades. Ideally, a balanced windmill will not deviate a single degree, but will remain motionless. If the blade has turned under its own weight, it needs to be slightly corrected, reduce the weight on one side, eliminate the deviation from the axis.
The process is repeated until the screw is completely fixed in any position. It is important that there is no wind during balancing. This may distort test results.
It is also important to ensure that all parts rotate strictly in the same plane. To check at a distance of 2 mm on both sides of one of the blades install control plates. While moving, no part of the screw should touch the plate.
To operate a wind generator with blades made will need to assemble a system that accumulates the received energy, preserves it and transfers it to the consumer. One of the components of the system is the controller. How to make controller for windmill, learn, having familiarized with article recommended by us.
Conclusions and useful video on the topic
Build a wind turbine with your own hands from scrap materials is quite possible. If you start with simpler models, then the first attempt will probably be successful. With experience, take on more complex ideas to get the most efficient and powerful wind generator.
Video # 1. How to make a PVC pipe windmill:
Video # 2. Wind generator with their own hands:
Video # 3. Galvanized steel turbine:
If you want to use clean and safe wind energy for domestic use and do not plan to spend huge money to buy expensive equipment, homemade blades made of ordinary materials would be a good idea. Do not be afraid to experiment, and you will be able to further improve the existing models of wind turbine screws.
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