General working principle

The main working body of the wind generator is the blades, which are rotated by the wind. Depending on the location of the axis of rotation, wind generators are divided into horizontal and vertical:

• Horizontal wind turbines most widespread. Their blades have a design similar to an airplane propeller: in the first approximation, these are plates inclined relative to the plane of rotation, which convert part of the load from wind pressure into rotation. An important feature of a horizontal wind generator is the need to ensure the rotation of the blade assembly in accordance with the direction of the wind, since the maximum efficiency is ensured when the direction of the wind is perpendicular to the plane of rotation.
• Blades vertical wind turbine have a convex-concave shape. Since the streamlining of the convex side is greater than the concave side, such a wind turbine always rotates in one direction, regardless of the direction of the wind, which makes the turning mechanism unnecessary, unlike horizontal wind turbines. At the same time, due to the fact that at any given time, only a part of the blades performs useful work, and the rest only oppose rotation, The efficiency of a vertical windmill is much lower than that of a horizontal one: if for a three-blade horizontal wind generator this figure reaches 45%, then for a vertical one it will not exceed 25%.

Since the average wind speed in Russia is not high, even a large wind turbine will rotate rather slowly most of the time. To ensure sufficient power, the power supply must be connected to the generator through a step-up reducer, belt or gear. In a horizontal windmill, the blade-reducer-generator unit is mounted on a swivel head, which enables them to follow the direction of the wind. It is important to take into account that the swivel head must have a limiter that prevents it from making a full turn, since otherwise the wiring from the generator will be cut off (the option using contact washers that allow the head to rotate freely is more complicated). To ensure rotation, the wind generator is supplemented with a working weather vane directed along the axis of rotation.

The most common blade material is large diameter PVC pipes cut lengthwise. Along the edge, metal plates are riveted to them, welded to the hub of the blade assembly. Drawings of this kind of blades are the most widespread on the Internet.

The video tells about a self-made wind generator

Calculation of a bladed wind turbine

Since we have already found out that a horizontal wind turbine is much more efficient, we will consider the calculation of its design.

Wind energy can be determined by the formula
P = 0.6 * S * V³, where S is the area of ​​the circle described by the tips of the rotor blades (throwing area), expressed in square meters, and V is the calculated wind speed in meters per second. You also need to take into account the efficiency of the windmill itself, which for a three-blade horizontal circuit will average 40%, as well as the efficiency of the generator set, which at the peak of the current-speed characteristic is 80% for a generator with permanent magnet excitation and 60% for a generator with an excitation winding. On average, another 20% of the power will be consumed by the step-up gear (multiplier). Thus, the final calculation of the radius of the wind turbine (that is, the length of its blade) for a given power of the permanent magnet generator looks like this:
R = √ (P / (0.483 * V³))

Example: Let's assume the required power of the wind farm is 500 W, and the average wind speed is 2 m / s. Then, according to our formula, we will have to use blades with a length of at least 11 meters. As you can see, even such a small power will require the creation of a wind generator of colossal dimensions. For more or less rational structures with a blade length of no more than one and a half meters in the conditions of do-it-yourself manufacturing, the wind generator will be able to produce only 80-90 watts of power even in strong winds.

Not enough power? In fact, everything is somewhat different, since in fact the load of the wind generator is fed by the batteries, the wind turbine only charges them to the best of its capabilities. Consequently, the power of a wind turbine determines the frequency with which it can supply energy.

Russia has a twofold position in relation to wind energy resources. On the one hand, due to the huge total area and the abundance of flat areas, there is generally a lot of wind, and it is mostly flat. On the other hand, our winds are mostly low-grade, slow, see fig. On the third, the winds are violent in sparsely populated areas. Based on this, the task of starting a wind generator on the farm is quite relevant. But, in order to decide whether to buy a rather expensive device, or to make it yourself, you need to think carefully about which type (and there are a lot of them) for which purpose to choose.

Basic concepts

1. KIEV - coefficient of use of wind energy. If used for calculating a mechanistic model of a plane wind (see below), it is equal to the efficiency of the rotor of a wind power plant (APU).
2. Efficiency - end-to-end efficiency of the APU, from the oncoming wind to the terminals of the electric generator, or to the amount of water pumped into the tank.
3. The minimum operating wind speed (MWS) is its speed at which the wind turbine begins to supply current to the load.
4. The maximum permissible wind speed (MDS) is its speed at which the generation of energy stops: automation either turns off the generator, or puts the rotor in a weather vane, or folds it and hides it, or the rotor stops itself, or the APU simply collapses.
5. Starting wind speed (SWS) - at this speed, the rotor can turn without load, spin up and enter the operating mode, after which you can turn on the generator.
6. Negative starting speed (OSS) - this means that the APU (or wind turbine - wind power plant, or VEA, wind power unit) to start at any wind speed requires mandatory spin-up from an external energy source.
7. Starting (initial) torque - the ability of a rotor, forcibly decelerated in an air flow, to create a torque on the shaft.
8. A wind turbine (VD) is a part of the APU from the rotor to the shaft of a generator or pump, or other energy consumer.
9. Rotary wind generator - APU, in which wind energy is converted into torque on the power take-off shaft by rotating the rotor in the air stream.
10. Rotor operating speed range is the difference between MDS and MPC when operating at rated load.
11. Slow-speed windmill - in it the linear speed of the rotor parts in the stream does not significantly exceed the wind speed or below it. The dynamic flow head is directly converted into blade thrust.
12. High-speed windmill - the linear speed of the blades is significantly (up to 20 or more times) higher than the wind speed, and the rotor forms its own air circulation. The cycle of converting the flow energy into thrust is complex.

Notes:

1. Low-speed APUs, as a rule, have KIEV lower than high-speed ones, but have a starting torque sufficient to spin up the generator without disconnecting the load and zero TCO, i.e. completely self-starting and applicable in the lightest winds.
2. Slowness and speed are relative concepts. A household wind turbine with 300 rpm can be low-speed, and powerful APUs of the EuroWind type, from which the fields of wind power plants, wind farms (see Fig.) And whose rotors make about 10 rpm, are high-speed, because with such their diameter, the linear velocity of the blades and their aerodynamics over the greater part of their span are quite “airplane-like,” see below.

What kind of generator do you need?

An electric generator for a household wind turbine must generate electricity in a wide range of rotation speeds and have the ability to self-start without automation and external power sources. In the case of using an APU with OSS (wind turbines with spinning), which, as a rule, have high KIEV and efficiency, it must also be reversible, i.e. be able to work as an engine. At powers up to 5 kW, this condition is met by electric machines with permanent magnets based on niobium (super magnets); on steel or ferrite magnets, you can count on no more than 0.5-0.7 kW.

Note: asynchronous alternators or collector generators with a non-magnetized stator are not suitable at all. When the wind force decreases, they "go out" long before its speed drops to the MPC, and then they themselves will not start.

An excellent "heart" of an APU with a capacity of 0.3 to 1-2 kW is obtained from an alternating current autogenerator with a built-in rectifier; these are now the majority. Firstly, they keep the output voltage of 11.6-14.7 V in a fairly wide range of speeds without external electronic stabilizers. Second, the silicon gates open when the voltage across the winding reaches approximately 1.4 V, and before that the generator “does not see” the load. To do this, the generator needs to be spinned up pretty well.

In most cases, the autogenerator can be directly, without a gear or belt drive, connected to the high-speed HP shaft, by selecting the speed by choosing the number of blades, see below. "Fast-walkers" have a small or zero starting torque, but the rotor will have enough time to spin up enough without disconnecting the load before the valves open and the generator will give current.

Choice by the wind

Before deciding which wind generator to make, let's decide on the local aerology. In gray-greenish(windless) areas of the wind map at least some sense will only be from a sailing wind turbine(and we'll talk about them further). If you need a constant power supply, you will have to add a booster (a rectifier with a voltage stabilizer), a charger, a powerful battery, an inverter 12/24/36/48 V DC to 220/380 V 50 Hz AC. Such an economy will cost no less than $ 20,000, and it is unlikely that it will be possible to remove a long-term power of more than 3-4 kW. In general, with an adamant striving for alternative energy, it is better to look for another source of it.

In yellow-green, weakly windy places, if the need for electricity is up to 2-3 kW, you can take on a slow-speed vertical wind generator yourself... They have been developed innumerable, and there are designs that in terms of KIEV and efficiency are almost not inferior to industrial-made "blades".

If a wind turbine for a house is supposed to be bought, then it is better to focus on a wind turbine with a sail rotor. There are a lot of disputes, and in theory everything is not yet clear, but they work. In the Russian Federation "sailboats" are produced in Taganrog with a capacity of 1-100 kW.

In red, windy regions, the choice depends on the required power. In the range of 0.5-1.5 kW, self-made "verticals" are justified; 1.5-5 kW - purchased "sailboats". "Vertical" can also be purchased, but it will cost more than a horizontal APU. And, finally, if a wind turbine with a power of 5 kW or more is required, then you need to choose between horizontal purchased "blades" or "sailboats".

Note: many manufacturers, especially of the second tier, offer kits of parts from which you can assemble a wind generator with a capacity of up to 10 kW yourself. Such a set will cost 20-50% cheaper than a ready-made one with installation. But before buying, you need to carefully study the aerology of the proposed installation site, and then, according to the specifications, select the appropriate type and model.

About safety

Parts of a household wind turbine in operation can have a linear speed exceeding 120 or even 150 m / s, and a piece of any solid material weighing 20 g, flying at a speed of 100 m / s, with a "successful" hit, kills a healthy man on the spot. A steel, or hard plastic, plate 2 mm thick, moving at a speed of 20 m / s, cuts it in half.

In addition, most wind turbines over 100 W are quite noisy. Many generate ultra-low (less than 16 Hz) air pressure fluctuations - infrasounds. Infrasounds are inaudible, but destructive to health, and spread very far.

Note: in the late 1980s, there was a scandal in the United States - the largest wind farm in the country at that time had to be closed. The Indians from the reservation 200 km from the field of its APU proved in court that the health disorders that have sharply increased after the WPP was put into operation are due to its infrasound.

For the above reasons, the installation of the APU is allowed at a distance of at least 5 of their heights from the nearest residential buildings. In the courtyards of private households, you can install industrial-made wind turbines, appropriately certified. It is generally impossible to install an APU on the roofs - during their operation, even with low-power ones, alternating mechanical loads arise that can cause a resonance of the building structure and its destruction.

Note: APU height is the highest point of the swept disk (for blade rotors) or geomeric figure (for vertical APU with a rotor on the shaft). If the APU mast or the rotor axis protrude upward even higher, the height is calculated from their top - the top.

Wind, aerodynamics, KIEV

A home-made wind generator obeys the same laws of nature as a factory one, calculated on a computer. And the home-builder needs to understand the basics of his work very well - most often he does not have at his disposal expensive super-modern materials and technological equipment. The aerodynamics of the APU is, oh, how difficult it is ...

Wind and KIEV

To calculate the serial factory APU, the so-called. flat mechanistic wind model. It is based on the following assumptions:

• Wind speed and direction are constant within the effective rotor surface.
• Air is a continuous medium.
• The effective surface of the rotor is equal to the swept area.
• The energy of the air flow is purely kinetic.

Under such conditions, the maximum energy per unit volume of air is calculated according to the school formula, assuming the air density under normal conditions is 1.29 kg * cubic meters. m. At a wind speed of 10 m / s, one cube of air carries 65 J, and 650 watts can be removed from one square of the effective rotor surface, at 100% efficiency of the entire APU. This is a very simplistic approach - everyone knows that the wind is never perfectly flat. But this has to be done in order to ensure the repeatability of products - a common practice in technology.

The flat model should not be ignored; it provides a clear minimum of available wind power. But the air, firstly, is compressed, and secondly, it is very fluid (dynamic viscosity is only 17.2 μPa * s). This means that the flow can flow around the swept area, reducing the effective surface and KIEV, which is most often observed. But, in principle, the opposite situation is also possible: the wind flows to the rotor and the effective surface area will then be greater than the swept surface, and the KIEV will be greater than 1 relative to the same for a flat wind.

Here are two examples. The first is a pleasure yacht, rather heavy, the yacht can go not only against the wind, but also faster than it. Wind is meant outside; the apparent wind must still be faster, otherwise how will it pull the ship?

The second is a classic of aviation history. During the tests of the MIG-19, it turned out that the interceptor, which was a ton heavier than the front-line fighter, accelerated faster in speed. With the same engines in the same glider.

Theorists did not know what to think, and seriously doubted the law of conservation of energy. In the end, it turned out that it was the radar fairing cone protruding from the air intake. From its nose to the shell, an air seal appeared, as if raking it from the sides to the engine compressors. Since then, shockwaves have become firmly established in theory as useful, and the fantastic flight performance of modern aircraft is in no small part due to their skillful use.

Aerodynamics

The development of aerodynamics is usually divided into two eras - before N. G. Zhukovsky and after. His report "On the attached vortices" of November 15, 1905 marked the beginning of a new era in aviation.

Prior to Zhukovsky, they flew on sails set flat: it was assumed that the particles of the incoming stream give all their momentum to the leading edge of the wing. This made it possible to immediately get rid of the vector quantity - the angular momentum - which gave rise to furious and most often non-analytical mathematics, to move to much more convenient scalar purely energy relations, and as a result obtain the calculated pressure field on the bearing plane, more or less similar to the present.

Such a mechanistic approach made it possible to create vehicles that, at the very least, can take off and fly from one place to another, not necessarily crashing to the ground somewhere along the way. But the desire to increase speed, carrying capacity and other flying qualities more and more revealed the imperfection of the original aerodynamic theory.

Zhukovsky's idea was this: along the upper and lower surfaces of the wing, the air travels a different path. From the condition of the continuity of the medium (vacuum bubbles are not formed in the air by themselves), it follows that the velocities of the upper and lower flows descending from the trailing edge should be different. Due to the small, but finite viscosity of the air, a vortex should form there due to the difference in velocities.

The vortex rotates, and the law of conservation of momentum, as immutable as the law of conservation of energy, is also valid for vector quantities, i.e. must take into account the direction of movement. Therefore, right there, at the trailing edge, an oppositely rotating vortex with the same torque should be formed. By what means? Due to the energy generated by the engine.

For aviation practice, this meant a revolution: by choosing the appropriate wing profile, it was possible to send the attached vortex around the wing in the form of a circulation G, increasing its lift. That is, having spent a part, and for high speeds and wing loads - a large part, the engine power, it is possible to create an air flow around the device, which allows to achieve the best flight characteristics.

This made aviation an aviation, and not a part of aeronautics: now the aircraft could create itself the environment necessary for flight and no longer be a toy of air currents. All you need is a more powerful engine, and more and more powerful ...

KIEV again

But the windmill has no motor. On the contrary, it must take energy from the wind and give it to consumers. And here it comes out - he pulled out his legs, the tail got stuck. Too little wind energy was allowed on the rotor's own circulation - it will be weak, the thrust of the blades will be low, and the KIEV and power will be low. Let's give a lot for circulation - in a weak wind, the rotor will spin like mad at idle, but consumers again get little: they gave a little load, the rotor braked, the wind blew off the circulation, and the rotor became.

The law of conservation of energy gives a "golden mean" just in the middle: we give 50% of the energy to the load, and for the remaining 50% we twist the flow to the optimum. Practice confirms the assumptions: if the efficiency of a good pulling propeller is 75-80%, then the KIEV, just as carefully calculated and blown in a wind tunnel, the blade rotor reaches 38-40%, i.e. up to half of what can be achieved with an excess of energy.

Modernity

Nowadays, aerodynamics, armed with modern mathematics and computers, is increasingly moving away from inevitably something and simplifying models to an accurate description of the behavior of a real body in a real flow. And here, in addition to the general line - power, power, and more power! - side paths are found, but promising just with a limited amount of energy entering the system.

The famous alternative aviator Paul McCready created an airplane back in the 80s, with two motors from a chainsaw with a capacity of 16 hp. showing 360 km / h. Moreover, its chassis was non-retractable tricycle, and the wheels were without fairings. None of McCready's vehicles went online and went on alert, but two - one with piston motors and propellers, and the other jet - flew around the globe for the first time in history without landing at one gas station.

The development of the theory also affected the sails that gave birth to the original wing very significantly. "Live" aerodynamics allowed the yachts in 8 knots wind. stand on hydrofoils (see fig.); to accelerate such a whopper to the required speed with a propeller, an engine of at least 100 hp is required. Racing catamarans sail at about 30 knots in the same wind. (55 km / h).

There are also completely non-trivial finds. Fans of the rarest and most extreme sport - base jumping - wearing an apecial wing suit, wingsuit, fly without a motor, maneuvering, at a speed of more than 200 km / h (picture on the right), and then smoothly land in a pre-selected place. In what fairy tale do people fly by themselves?

Many mysteries of nature have also been resolved; in particular - the flight of a beetle. According to classical aerodynamics, it is not capable of flying. In the same way as the ancestor of the "stealth" F-117 with its diamond-shaped wing, too, is not able to rise into the air. And the MiG-29 and Su-27, which for some time can fly with their tail forward, do not fit into any ideas at all.

And why then, when dealing with wind turbines, not as fun and not as a tool for destroying their own kind, but as a source of a vital resource, it is imperative to dance from the theory of weak streams with its model of a flat wind? Is there really no way to move forward?

What to expect from a classic?

However, in no case should one give up the classics. It provides a foundation, without leaning on which one cannot rise higher. In the same way, as set theory does not cancel the multiplication table, and quantum chromodynamics does not make apples fly up from the trees.

So what can you expect with the classic approach? Let's look at the picture. Left - types of rotors; they are shown conditionally. 1 - vertical carousel, 2 - vertical orthogonal (wind turbine); 2-5 - bladed rotors with a different number of blades with optimized profiles.

On the right, along the horizontal axis, the relative rotor speed is plotted, i.e., the ratio of the linear speed of the blade to the wind speed. Vertical upwards - KIEV. And down - again, the relative torque. A single (100%) torque is considered to be the one that creates a rotor forcibly braked in the flow with 100% KIEV, i.e. when all the energy of the flow is converted into a rotating force.

This approach allows for far-reaching conclusions. For example, the number of blades must be chosen not only and not so much according to the desired rotation speed: 3- and 4-blades immediately lose a lot in terms of KIEV and torque compared to 2- and 6-blades that work well in approximately the same speed range. And outwardly similar carousel and orthogonal have fundamentally different properties.

In general, preference should be given to vane rotors, except for cases when the utmost cheapness, simplicity, maintenance-free self-starting without automation are required and lifting to the mast is impossible.

Note: let's talk about sailing rotors especially - they don't seem to fit into the classics.

Vertical

APUs with a vertical axis of rotation have an indisputable advantage for everyday life: their units requiring maintenance are concentrated at the bottom and there is no need to lift them up. There remains, and even then not always, a self-aligning thrust bearing, but it is strong and durable. Therefore, when designing a simple wind turbine, the selection of options should be started with vertical units. Their main types are shown in Fig.

Sun

In the first position - the simplest, most often called the Savonius rotor. In fact, it was invented in 1924 in the USSR by Ya. A. and A. A. Voronin, and the Finnish industrialist Sigurd Savonius shamelessly appropriated the invention, ignoring the Soviet copyright certificate, and began serial production. But the introduction in the fate of the invention means a lot, therefore, in order not to stir up the past and not disturb the ashes of the dead, we will call this wind turbine the Voronin-Savonius rotor, or, for short, VS.

VS is good for a home-builder, except for the "locomotive" KIEV in 10-18%. However, in the USSR they worked a lot on it, and there are some developments. Below we will consider an improved design, which is not much more complex, but according to KIEV gives a head start to blades.

Note: the two-bladed aircraft does not spin, but jerks; The 4-blade is only slightly smoother, but loses a lot in KIEV. To improve the 4 - "trough" ones are most often carried over two floors - a pair of blades at the bottom, and another pair, rotated 90 degrees horizontally, above them. The KIEV remains, and the lateral loads on the mechanics are weakened, but the bending loads slightly increase, and with a wind of more than 25 m / s, such an APU on the shaft, i.e. without the bearing over the rotor stretched by the shrouds, "tears down the tower".

Daria

The next is the Darrieus rotor; KIEV - up to 20%. It is even simpler: the blades are made of a simple elastic band without any profile. Darrieus's rotor theory has not yet been sufficiently developed. It is only clear that it begins to unwind due to the difference in the aerodynamic resistance of the hump and the pocket of the tape, and then it becomes kind of fast, forming its own circulation.

The torque is small, and in the starting positions of the rotor there is no parallel or perpendicular to the wind at all, so self-spinning is possible only with an odd number of blades (wings?). In any case, the load from the generator must be disconnected during spin-up.

The Darrieus rotor has two more bad qualities. First, during rotation, the thrust vector of the blade describes a complete revolution relative to its aerodynamic focus, and not smoothly, but in jerks. Therefore, the Darrieus rotor quickly breaks its mechanics even in an even wind.

Secondly, Daria is not just making noise, but screaming and screeching, to the point that the tape breaks. This is due to its vibration. And the more blades, the stronger the roar. So, if Daria is made, it is two-bladed, made of expensive high-strength sound-absorbing materials (carbon fiber, mylar), and a small aircraft is adapted for spinning in the middle of the mast-pole.

Orthogonal

On pos. 3 - orthogonal vertical rotor with profiled blades. Orthogonal because the wings stick out vertically. The transition from the VS to the orthogonal is illustrated in Fig. left.

The angle of installation of the blades relative to the tangent to the circle touching the aerodynamic foci of the wings can be either positive (in the figure) or negative, in accordance with the strength of the wind. Sometimes the blades are made swiveling and weather vans are placed on them, automatically holding the "alpha", but such structures often break.

The central body (blue in the figure) allows you to bring the KIEV to almost 50% In a three-bladed orthogonal, it should have the shape of a triangle in section with slightly convex sides and rounded corners, and with a larger number of blades, a simple cylinder is sufficient. But the theory for the orthogonal gives the optimal number of blades unambiguously: there should be exactly 3 of them.

Orthogonal refers to high-speed wind turbines with OSS, i.e. necessarily requires promotion during commissioning and after calm. Serial unattended APUs with a capacity of up to 20 kW are produced according to the orthogonal scheme.

Helicoid

Helicoid rotor, or Gorlov's rotor (pos. 4) - a kind of orthogonal, providing uniform rotation; the orthogonal with straight wings “tears” only slightly weaker than the two-bladed BC. The bending of the blades along the helicoid makes it possible to avoid losses of KIEV due to their curvature. Although the curved blade rejects part of the flow without using it, it also rakes part of it into the zone of the highest linear velocity, compensating for the losses. Helicoids are used less often than other wind turbines, because due to the complexity of manufacturing, they turn out to be more expensive than their counterparts of equal quality.

Barrel-zagrebka

5 pos. - BC type rotor surrounded by a guide vanes; its diagram is shown in Fig. on right. It is rarely found in industrial design, because expensive land acquisition does not compensate for the increase in capacity, and the consumption of materials and the complexity of production are great. But a home-builder who is afraid of work is no longer a master, but a consumer, and if no more than 0.5-1.5 kW is needed, then a tidbit for him:

• A rotor of this type is absolutely safe, silent, does not create vibrations and can be installed anywhere, even on a playground.
• To bend galvanized troughs and weld a frame from pipes is a nonsense job.
• The rotation is absolutely uniform, the mechanical parts can be taken from the cheapest or from the trash.
• Not afraid of hurricanes - too strong wind cannot push into the "barrel"; a streamlined vortex cocoon appears around it (we will encounter this effect later).
• And most importantly, since the surface of the "grab" is several times larger than that of the rotor inside, the KIEV can be over-unit, and the torque already at 3 m / s at the "barrel" of three-meter diameter is such that a 1 kW generator with a maximum load is it is said that it is better not to twitch.

Video: Lenz wind turbine

In the 60s in the USSR E.S.Biryukov patented a carousel APU with 46% KIEV. A little later, V. Blinov achieved 58% of the design based on the same KIEV principle, but there is no data on its tests. And full-scale tests of the Armed Forces of Biryukov were carried out by the staff of the Inventor and Rationalizer magazine. A two-storey rotor with a diameter of 0.75 m and a height of 2 m in a fresh wind spun an asynchronous generator of 1.2 kW at full power and withstood 30 m / s without breaking. Biryukov's APU drawings are shown in Fig.

1. galvanized roof rotor;
2. self-aligning double row ball bearing;
3. cables - 5 mm steel cable;
4. shaft axis - steel pipe with a wall thickness of 1.5-2.5 mm;
5. aerodynamic speed control levers;
6. speed governor blades - 3-4 mm plywood or plastic sheet;
7. rods of the speed regulator;
8. the load of the speed controller, its weight determines the speed;
9. drive pulley - a bicycle wheel without a tire with a tube;
10. thrust bearing - thrust bearing;
11. driven pulley - standard alternator pulley;
12. generator.

Biryukov received several copyright certificates for his APU. First, notice the cutaway of the rotor. When accelerating, it works like an aircraft, creating a great starting moment. As the spin progresses, a vortex cushion is created in the outer pockets of the blades. From the wind point of view, the blades become profiled, and the rotor turns into a high-speed orthogonal, with the virtual profile changing according to the wind strength.

Secondly, the profiled channel between the blades in the operating speed range acts as a central body. If the wind increases, then a vortex cushion is also created in it, extending beyond the rotor. The same vortex cocoon appears as around the APU with the guide vanes. The energy for its creation is taken from the wind, and it is no longer enough for the breakdown of the windmill.

Thirdly, the speed controller is designed primarily for the turbine. He keeps her turnover optimal from the point of view of KIEV. And the optimum generator speed is ensured by the choice of the gear ratio of the mechanics.

Note: after publications in the IR for 1965, the Armed Forces of Ukraine Biryukova sank into oblivion. The author did not receive a response from the authorities. The fate of many Soviet inventions. They say that some Japanese became a billionaire, regularly reading Soviet popular technical magazines and patenting everything that deserves attention.

Blades

As stated above, a horizontal vane-rotor wind turbine is the best in the classics. But, firstly, he needs a stable, at least medium-strength wind. Secondly, the construction for the DIYer is fraught with a lot of pitfalls, which is why often the fruit of long hard work, at best, illuminates the toilet, hallway or porch, or even turns out to be only able to untwist itself.

According to the diagrams in Fig. let's take a closer look; positions:

• FIG. A:

1. rotor blades;
2. generator;
3. generator bed;
4. protective weather vane (hurricane shovel);
5. current collector;
6. chassis;
7. swivel knot;
8. working weather vane;
9. mast;
10. clamp for cables.

• FIG. B, top view:

1. protective weather vane;
2. working weather vane;
3. spring tension regulator of the protective vane.

• FIG. G, slip ring:

1. a collector with continuous copper ring busbars;
2. spring loaded copper-graphite brushes.

Note: hurricane protection for a horizontal vane with a diameter of more than 1 m is absolutely necessary, because he is not capable of creating a vortex cocoon around himself. With smaller dimensions, rotor endurance of up to 30 m / s can be achieved with propylene blades.

So where are the stumbling blocks?

Blades

Expect to achieve a power on the generator shaft of more than 150-200 W on blades of any size, cut from a thick-walled plastic pipe, as is often advised, are the hopes of a hopeless amateur. A vane made of a pipe (unless it is so thick that it is simply used as a blank) will have a segmented profile, i.e. its top, or both, will be circular arcs.

Segment profiles are suitable for an incompressible medium, such as hydrofoils or propeller blades. For gases, a blade of variable profile and pitch is needed, for example, see fig.; span - 2 m. It will be a complex and time-consuming product that requires painstaking calculation fully armed with theory, blowing in a pipe and full-scale tests.

Generator

When the rotor is mounted directly on its shaft, the standard bearing will soon break - the same load on all blades in wind turbines does not happen. You need an intermediate shaft with a special support bearing and a mechanical transmission from it to the generator. For large wind turbines, a self-aligning double-row bearing is taken; in the best models - three-tiered, Fig. D in Fig. above. This allows the rotor shaft not only to bend slightly, but also to move slightly from side to side or up and down.

Note: it took about 30 years to develop a thrust bearing for the EuroWind APU.

Emergency weather vane

The principle of its operation is shown in FIG. C. The wind, increasing, presses on the shovel, the spring stretches, the rotor twists, its revolutions fall, and in the end it becomes parallel to the flow. Everything seems to be fine, but it was smooth on paper ...

On a windy day, try holding a boil lid or a large saucepan by the handle parallel to the wind. Only carefully - a fidgety piece of iron can hit the face in such a way that it rubs the nose, cuts the lip, or even knocks out the eye.

Flat wind occurs only in theoretical calculations and, with sufficient accuracy for practice, in wind tunnels. In reality, a hurricane wind turbines with a hurricane shovel mangle more than completely defenseless ones. It is better to change the warped blades after all than to do everything again. In industrial installations, it is a different matter. There, the pitch of the blades, one at a time, is monitored and adjusted by the automation under the control of the on-board computer. And they are made from heavy-duty composites, not from water pipes.

Current collector

This is a regularly serviced site. Any power engineer knows that a collector with brushes needs to be cleaned, lubricated, and regulated. And the mast is made of a water pipe. You will not get in, once a month or two you will have to throw the whole windmill on the ground and then raise it again. How long will it last from such "prevention"?

Video: bladed wind generator + solar panel for power supply of the summer cottage

Mini and micro

But with a decrease in the size of the vane, the difficulties fall along the square of the diameter of the wheel. It is already possible to manufacture a horizontal blade APU on its own for a power of up to 100 W. A 6-blade would be optimal. With more blades, the rotor diameter for the same power will be smaller, but it will be difficult to secure them firmly on the hub. Rotors of less than 6 blades can be ignored: a 100 W 2-blade needs a 6.34 m diameter rotor, and a 4-blade of the same power needs 4.5 m. For a 6-blade, the power - diameter dependence is expressed as follows :

• 10 W - 1.16 m.
• 20 W - 1.64 m.
• 30 W - 2 m.
• 40 W - 2.32 m.
• 50 W - 2.6 m.
• 60 W - 2.84 m.
• 70 W - 3.08 m.
• 80 W - 3.28 m.
• 90 W - 3.48 m.
• 100 W - 3.68 m
• 300 W - 6.34 m.

The best will be to count on a power of 10-20 watts. Firstly, a plastic blade with a span of more than 0.8 m will not withstand winds exceeding 20 m / s without additional protection measures. Secondly, with a blade span of up to the same 0.8 m, the linear speed of its ends will not exceed the wind speed by more than three times, and the requirements for profiling with twist are reduced by orders of magnitude; here a "trough" with a segmented profile from a pipe, pos. B in Fig. And 10-20 W will provide power to the tablet, recharge the smartphone or light up the housekeeper light.

Next, select the generator. A Chinese motor is perfect - a wheel hub for electric bicycles, pos. 1 in fig. Its power as a motor is 200-300 W, but in generator mode it will give about 100 W. But will it suit us in terms of turnover?

The speed index z for 6 blades is 3. The formula for calculating the rotational speed under load is N = v / l * z * 60, where N is the rotational speed, 1 / min, v is the wind speed, and l is the rotor circumference. With a blade span of 0.8 m and a wind of 5 m / s, we get 72 rpm; at 20 m / s - 288 rpm. The bicycle wheel rotates at about the same speed, so we will remove our 10-20 watts from a generator capable of giving 100. You can fit the rotor directly onto its shaft.

But here the following problem arises: we, having spent a lot of labor and money, at least for a motor, got ... a toy! What is 10-20, well, 50 watts? And you can't make a bladed windmill capable of powering at least a TV at home. Is it possible to buy a ready-made mini-wind generator, and will it cost less? As much as possible, and even as cheaper, see pos. 4 and 5. In addition, it will also be mobile. Put it on a tree stump - and use it.

The second option is if a stepper motor is lying somewhere from an old 5- or 8-inch drive, or from a paper drive or a carriage of an unusable inkjet or dot-matrix printer. It can work as a generator, and it is easier to attach a carousel rotor from cans (pos. 6) to it than to assemble a structure like that shown in pos. 3.

In general, the conclusion about the "blades" is unambiguous: self-made - more likely in order to tweak to your heart's content, but not for real long-term energy output.

Video: the simplest wind generator for lighting a summer cottage

Sailboats

The sailing wind generator has been known for a long time, but the soft panels of its blades (see Fig.) Began to be made with the advent of high-strength wear-resistant synthetic fabrics and films. Multi-blade windmills with rigid sails are widely distributed around the world as a drive for low-power automatic water pumps, but their technical data are lower even than those of carousels.

However, a soft sail like the wing of a windmill, it seems, turned out to be not so simple. It's not about wind resistance (manufacturers do not limit the maximum permissible wind speed): sailing yachts already know that it is almost impossible for the wind to break the bermuda sails. Rather, the sheet will rip out, or the mast will break, or the whole vessel will make a "turn overkill". It's about energy.

Unfortunately, no precise test data can be found. According to user reviews, it was possible to draw up "synthetic" dependencies for the installation of a wind turbine-4.380 / 220.50 made in Taganrog with a wind wheel diameter of 5 m, a wind head weight of 160 kg and a rotational speed of up to 40 rpm; they are shown in Fig.

Of course, there can be no guarantees for 100% reliability, but even so it is clear that there is no sign of a flat-mechanistic model here. In no way can a 5-meter wheel on a flat wind of 3 m / s give about 1 kW, at 7 m / s reach a plateau in power and then hold it until a severe storm. Manufacturers, by the way, declare that nominal 4 kW can be obtained at 3 m / s, but when installed by their forces according to the results of local aerology studies.

There is no quantitative theory either; the developers' explanations are obscure. However, since the people buy the Taganrog wind turbines, and they work, it remains to assume that the declared conical circulation and the propulsive effect are not fiction. In any case, they are possible.

Then, it turns out, BEFORE the rotor, according to the law of conservation of momentum, there should also be a conical vortex, but expanding and slow. And such a funnel will drive the wind to the rotor, its effective surface will turn out to be more swept, and KIEV - over-unit.

Light on this question could be shed by field measurements of the pressure field in front of the rotor, at least with a household aneroid. If it turns out to be higher than from the sides to the side, then, indeed, the sailing APUs work like a beetle flies.

Homemade generator

From what has been said above, it is clear that it is better for home-builders to take on either verticals or sailboats. But both are very slow, and transferring to a high-speed generator is unnecessary work, unnecessary costs and losses. Can you make an efficient low-speed electric generator yourself?

Yes, you can, with magnets made of niobium alloy, the so-called. super magnets. The manufacturing process of the main parts is shown in Fig. Coils - each of 55 turns of copper 1 mm wire in heat-resistant high-strength enamel insulation, FEMM, PETV, etc. The height of the windings is 9 mm.

Pay attention to the keyways in the rotor halves. They must be located so that the magnets (they are glued to the magnetic circuit with epoxy or acrylic) after assembly come together with opposite poles. "Pancakes" (magnetic cores) must be made of a soft magnetic ferromagnet; regular structural steel will do. The thickness of the "pancakes" is at least 6 mm.

In general, it is better to buy magnets with an axial hole and tighten them with screws; super magnets attract with terrible force. For the same reason, a cylindrical spacer 12 mm high is put on the shaft between the "pancakes".

The windings that make up the stator sections are connected according to the diagrams also shown in Fig. The soldered ends should not be stretched, but should form loops, otherwise the epoxy, which will be flooded with the stator, hardening, may break the wires.

The stator is poured into the mold to a thickness of 10 mm. There is no need to center and balance, the stator does not rotate. The gap between the rotor and the stator is 1 mm on each side. The stator in the generator housing must be securely fixed not only against axial displacement, but also against turning; a strong magnetic field with a current in the load will pull it along.

Video: DIY wind turbine generator

Output

And what do we have in the end? Interest in "blades" is explained rather by their spectacular appearance than by the actual performance in a homemade design and at low power. A self-made carousel APU will provide "standby" power for charging a car battery or supplying power to a small house.

But with the sailing APU, it is worth experimenting with masters with a creative streak, especially in a mini version, with a wheel of 1-2 m in diameter. If the assumptions of the developers are correct, then it will be possible to remove from this, by means of the Chinese engine-generator described above, all of its 200-300 watts.

Andrey said:

Thanks for your free consultation ... And the prices "from firms" are not really expensive, and I think that artisans from the provinces will be able to make generators similar to yours. And Li-po batteries can be ordered from China, inverters in Chelyabinsk are very good sine) .And sails, blades or rotors - this is another reason for the flight of thought of our handy Russian men.

Ivan said:

question:
For wind turbines with a vertical axis (position 1) and the “Lenz” version, it is possible to add an additional detail - an impeller, which is exposed to the wind, and closes the useless side from it (going towards the wind). That is, the wind will not slow down the blade, but this “screen”. Setting in the wind with the "tail" located behind the windmill itself below and above the blades (ridges). I read the article and an idea was born.

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The power of a home-made wind generator will be enough to charge batteries for various equipment, provide lighting and, in general, the operation of household electrical appliances. By installing a wind turbine, you save yourself the cost of electricity. If desired, the unit in question can be assembled by hand. You just need to decide on the main parameters of the wind generator and do everything in accordance with the instructions.

The design of the wind generator includes several blades that rotate under the influence of wind currents. As a result of this impact, rotational energy is generated. The generated energy is fed by the rotor to the multiplier, which in turn transfers the energy to the electric generator.

There are also wind turbine designs without multipliers. The absence of a multiplier can significantly increase the productivity of the installation.

Wind turbines can be installed both individually and in groups united in a wind farm. Also, wind turbines can be combined with diesel generators, which will save fuel and ensure the most efficient operation of the electrical supply system at home.

What do you need to know before assembling a wind turbine?

Before you start assembling a wind generator, you need to decide on a number of main points.

First step. Choose a suitable type of wind turbine design. Installation can be vertical or horizontal. In the case of self-assembly, it is better to give the choice in favor of vertical models, because they are easier to manufacture and balance.

Second step. Determine the appropriate power. In this moment, everything is individual - focus on your own needs. To obtain more power, it is necessary to increase the diameter and mass of the impeller.

An increase in these characteristics will lead to certain difficulties at the stage of fixing and balancing the wind turbine wheel. Consider this moment and objectively assess your capabilities. If you are a beginner, consider installing multiple medium-sized wind turbines instead of one very efficient unit.

Third step. Think about whether you can make all the elements of the wind generator yourself. Each detail must be accurately calculated and made in full accordance with the factory counterparts. In the absence of the necessary skills, it is better to buy ready-made elements.

Fourth step. Choose suitable batteries. It is better to refuse car batteries, because they are short-lived, explosive and demanding in care and maintenance.

Sealed batteries are preferred. They cost a couple of times more, but they serve several times longer and, in general, have higher performance.

Pay special attention to the selection of a suitable number of blades. The most popular are wind turbines with 2 and 3 blades. However, such installations have a number of disadvantages.

When a generator with 2 or 3 blades is operating, powerful centrifugal and gyroscopic forces take place. Under the influence of these forces, the load on the main elements of the wind generator increases significantly. Moreover, in some moments the forces act in opposition to each other.

In order to level the incoming loads and keep the structure of the wind turbine intact, you need to perform competent aerodynamic calculation of the blades and make them in exact accordance with the calculated data. Even minimal errors reduce the efficiency of the installation several times and increase the likelihood of an early breakdown of the wind generator.

High-speed wind turbines generate a lot of noise, especially when it comes to self-made installations. The larger the blades are, the louder the noise will be. This moment imposes a number of restrictions. For example, it will not be possible to install such a noisy structure on the roof of a house, unless, of course, the owner does not like the feeling of life in an airfield.

Keep in mind that as the number of blades increases, the level of vibration generated during the operation of the wind generator will increase. Two-blade sets are more difficult to balance, especially for the inexperienced user. Consequently, there will be a lot of noise and vibration from wind turbines with two blades.

Give a choice in favor of a wind generator with 5-6 blades. Practice shows that such models are the most optimal for self-production and use at home.

The screw is recommended to be made with a diameter of about 2 m. Almost anyone can handle the work of assembling and balancing it. With more experience, you can try to assemble and install a wheel with 12 blades. The assembly of such a unit will require more effort. Material consumption and time costs will also increase. However, 12 blades will allow, even with a weak wind of 6-8 m / s, to receive power at the level of 450-500 W.

Keep in mind that with 12 blades, the wheel will be quite slow-moving, and this can lead to various problems. For example, you have to assemble a special gearbox, which is more complicated and expensive to manufacture.

Thus, the best option for a novice home craftsman is a wind generator with a wheel with a diameter of 200 cm, equipped with medium-length blades in the amount of 6 pieces.

Accessories and tools for assembly

Assembling a wind turbine will require many different components and accessories. Collect and buy everything you need in advance so you don't have to be distracted by it in the future.

Depending on the conditions of a particular situation, the list of required tools may vary slightly. In this moment, you will independently orient yourself in the course of the work.

A step-by-step guide to assembling a wind turbine

The assembly and installation of a homemade wind generator is carried out in several stages.

First step. Prepare a three-point concrete base. Determine the depth and overall strength of the foundation in accordance with the type of soil and climatic conditions at the construction site. Allow the concrete to harden for 1 to 2 weeks and set up the mast. To do this, bury the support mast about 50-60 cm in the ground and fix it with guy ropes.

Second phase. Prepare the rotor and pulley. The pulley is a friction wheel. A groove or rim is located around the circumference of such a wheel. When choosing a rotor diameter, you need to be guided by the average annual wind speed. So, at an average speed of 6-8 m / s, a rotor with a diameter of 5 m will be more efficient than a rotor of 4 m.

Stage three. Make the blades of the future wind turbine. To do this, take a barrel and divide it into several equal parts in accordance with the selected number of blades. Mark the blades with a marker and then cut out the elements. A grinder is perfect for cutting, you can also use metal scissors.

Stage four. Attach the bottom of the drum to the generator pulley. Use bolts for fastening. After that, you need to bend the blades on the barrel. Do not overdo it, otherwise the finished installation will be unstable. Set the appropriate rotation speed of the wind turbine by changing the curvature of the blades.

Fifth stage. Connect the wires to the generator and collect them in a chain in a dose. Secure the generator to the mast. Connect the wires to the generator and mast. Assemble the generator into a chain. Also connect the battery to the circuit. Please note that the maximum permissible wire length for this installation is 100 cm. Connect the load with wires.

The assembly of one generator takes on average 3-6 hours, depending on the skills available and the overall performance and the master.

The wind turbine requires regular care and maintenance.

1. 2-3 weeks after installing a new generator, you need to dismantle the device and make sure that the existing fasteners are secure... For your own safety, check the mountings only in light winds.
2. Lubricate the bearings at least once every 6 months. When the first signs of imbalance appear on the wheel, immediately remove it and eliminate the existing malfunctions. The most common sign of imbalance is abnormal blade shaking.
3. Check pantograph brushes at least every 6 months... Every 2-6 years paint metal elements installation. Regular painting will protect the metal from corrosion damage.
4. Monitor the status of the generator... Check regularly that the generator does not overheat during operation. If the surface of the unit becomes so hot that it becomes very difficult to hold your hand on it, take the generator to a workshop.
5. Monitor the condition of the collector... Any contamination must be removed from the contacts as soon as possible. they significantly reduce the efficiency of the installation. Pay attention to the mechanical condition of the contacts. Overheating of the unit, burned out windings and other similar defects - all this must be immediately eliminated.

Thus, there is nothing complicated in assembling a wind turbine. It is enough just to prepare all the necessary elements, assemble the installation according to the instructions and connect the finished unit to the mains. A properly assembled wind generator for your home will become a reliable source of free electricity. Follow the tutorial and you will be fine.

Happy work!

Video - DIY wind turbines for home

For a long time, humanity has been using the power of the wind for its own purposes. Windmills, sailing ships are familiar to many, they write about them in books and make historical films. In our time, the wind power generator has not lost its relevance, because with its help, you can get free electricity in the country, which can come in handy if the lights are turned off. Let's talk about homemade wind turbines that can be assembled from scrap materials and available parts at a minimum cost. For you, we have provided one detailed instruction with pictures, as well as video ideas for several more assembly options. So, let's look at how to make a wind generator with your own hands at home.

Assembly instructions

There are several types of wind turbines, namely horizontal, vertical and turbine. They have fundamental differences, their pros and cons. However, the principle of operation of all wind generators is the same - wind energy is converted into electrical energy and accumulates in batteries, and already from them goes to human needs. The most common view is horizontal.

He is familiar and recognizable. The advantage of a horizontal wind turbine is a higher efficiency compared to others, since the blades of the wind turbine are always under the influence of the air flow. The disadvantages include a high wind requirement - it must be stronger than 5 meters per second. This type of windmill is the easiest to make, so it is often taken as a basis by DIYers.

If you decide to try your hand at assembling a wind generator with your own hands, here are some recommendations.

You need to start with the generator - this is the heart of the system; the design of the screw assembly will depend on its parameters. For this, automobile generators of domestic and foreign production are suitable, there is information about the use of stepper motors from printers or other office equipment. A bicycle wheel motor can also be used to make your own wind turbine to generate electricity. In general, almost any motor or generator can work, but it must be tested for efficiency.

Having decided on the energy converter, you need to assemble a gear unit to increase the speed on the generator shaft. One revolution of the propeller should be equal to 4-5 revolutions on the shaft of the generator unit. However, these parameters are selected individually, based on the power and characteristics of your generator and vane unit. A part from a grinder or a system of belts and rollers can act as a reducer.

When the gear-generator assembly is assembled, they begin to find out its resistance to torque (grams per millimeter). To do this, you need to make a shoulder with a counterweight on the shaft of the future installation, and with the help of a weight, find out at what weight the shoulder will go down. An acceptable result is less than 200 grams per meter. The shoulder size in this case is taken as the length of the blade.

Many people think that the more blades, the better. This is not entirely true. We need high rpm, and many screws create more wind resistance, since we make them at home, as a result of which at some point the oncoming flow slows down the propeller and the efficiency of the installation drops. You can use a two-blade propeller. Such a propeller in normal wind can spin more than 1000 rpm. You can make the blades of a homemade wind generator from improvised means - from plywood and galvanized steel, to plastic from water pipes (as in the photo below). The main condition is that the material must be lightweight and durable.

The lightweight propeller will increase the efficiency of the windmill and the sensitivity to air flow. Do not forget to balance the air wheel and remove irregularities, otherwise during the operation of the generator you will hear howling and howling, and vibrations will lead to rapid wear of parts.

The next important element is the tail. He will keep the wheel in the flow of the wind, and turn the structure in case of a change in its direction.

Whether or not to make a slip ring is up to you. This will complicate the design, however, it will save you from frequent twisting of the wire, which is fraught with cable breaks. Of course, in the absence of it, you will sometimes have to unwind the wire yourself. During the test run of the wind generator, do not forget about safety precautions, spinning blades are a great danger.

A tuned and balanced wind turbine is installed on a mast with a height of at least 7 meters from the ground, secured with spacer cables. Further, an equally important unit is the storage battery. The most commonly used car battery. You cannot connect the output of a homemade wind generator directly to the battery; this must be done through a charging relay or a controller, which you can assemble yourself or purchase a ready-made one.

The principle of operation of the relay is reduced to monitoring the charge and load. If the battery is fully charged, it switches the generator and the battery to load ballast, the system strives to always be charged, preventing overcharging, and does not leave the generator without load. A windmill without load can spin up quite strongly and damage the insulation in the windings with the generated potential. In addition, high speeds can cause mechanical destruction of the elements of the wind generator. Next is a voltage converter from 12 to 220 volts 50 Hz for connecting household appliances.

Now the Internet is full of diagrams and drawings where masters show how to make a wind generator with powerful magnets on their own. Whether they are as effective as they promise is a moot point. But it is worth trying to assemble a wind power generating installation for a home, and then decide how to improve it. It is important to gain experience and then you can already swing at a more serious apparatus. The freedom and variety of home-made wind turbines is so extensive, and the element base is diverse that it makes no sense to describe them all, the main meaning remains the same - the wind flow spins the screw, the gearbox increases the shaft speed, the generator gives out voltage, then the controller keeps the charge level on the battery, and with it is already taking energy for various needs. By this principle, you can make a wind generator with your own hands at home. We hope our detailed instructions with photo examples have explained to you how to make a suitable model of a windmill for your home or summer cottage. We also recommend that you familiarize yourself with the master classes on assembling a homemade device in video format.

Visual video tutorials

To easily make a wind generator for generating electricity at home, we recommend that you familiarize yourself with ready-made ideas in video examples:

So we have provided all the most simple and affordable ideas for assembling a homemade windmill. As you can see, even a child can easily make some models of devices. There are many other options for homemade products: with powerful magnets, with complex blades, etc. These constructions should be repeated only if you have some experience in this matter, you should start with simple schemes. If you want to make a wind generator so that it works and is used for its intended purpose, proceed according to the instructions provided by us. If you have any questions, leave them in the comments.