How many blades does a wind generator need? Are they needed at all? - Wind energy

Systematization of non-standard projects

Very conditionally, we can allow such a systematization of wind turbines that bypasses the typical ideas about generators using alternative energy sources:

Horizontal turbines;
Vertical turbines;
Bladeless wind generators;
Air wind generators (flying);

This proximity is caused by the extremely wide range of ideas among the inventors of wind turbines. Some systems seem so futuristic that it is impossible to believe in their implementation in practice. But the reality of the 21st century shows that if a rational and reasonable world can go crazy from the coronavirus panic, crazy projects can also be successfully implemented into working prototypes. And some of them are even ready for commercial release.

Operating principle of a wind generator

The operation of a wind generator is based on the conversion of the kinetic energy of the wind into the rotational energy of the transmission mechanism (blades-gearbox-transmission shaft) and further into the rotational energy of the electric generator shaft.

Continuation of the topic: Vertical wind generator 2

During rotation, an alternating electric current is generated in the generator windings. The generated electric current is supplied to the controller, converted and stored in batteries. From the batteries, the electric current is supplied to the inverter, where it is converted and supplied to the electrical network for use.

Wind generator components:

Blades - serve to capture wind flows, which causes them to rotate;
Gearbox - serves to convert the low-speed rotation speed of the blades into a higher one, allowing the generation of electric current;
Generator – converts kinetic energy into electrical energy;
Protective casing is an element protecting a technical device from a source of extraneous influences;
Shank - designed to ensure the direction of the blades in accordance with the direction of the wind;
Controller – serves to convert alternating current into direct current;
Rechargeable battery – designed to store generated electrical energy;
Inverter – converts direct electrical current into alternating current.

Variety of horizontal wind turbines

They began to improve standard installations through manipulation of the number of blades. In the mid-80s, the Germans replaced the usual three blades with two.

These two-bladed wind generators operated for several years in experimental mode, but they generated energy regularly. Some models were left, some were dismantled. And in places with strong winds, such as the UK coast, they still work.

The reason was to save materials. It was for this purpose that the first such installation was designed by the American Putnam back in 1941. She set a record for the power and height of wind generators, holding it until the mid-70s. It produced 1.25 mW. Although she worked intermittently only until 1946.

However, Dutch innovators went further. They decided that if a wind generator works with two blades, it will work with one! In addition, they became interested in such models in Italy, where several single-blade windmills are still operating in rural areas.

In the mid-70s, amid rising energy prices, NASA was tasked with developing the most efficient wind turbines. Over the course of several years, they implemented 6 concepts of different horizontal wind generators in test sites. All of them were designated MOD, series from 0A to 5B, and WTS 4.

The Yankees were getting screwed big time. All models were two-bladed, some of them were placed against the wind, i.e. the air flow first flowed around the gondola, and only then spun the blades. The WTS 4 project held the power record for 20 years with a 4 MW generator. A similar model with a 3 MW generator was built in Sweden, under the symbol WTS 3.

They did not dare to build the inclined structure MOD 5A; it remained on paper. And MOD 5B operated in Hawaii from 86 to 97.

Father and son Bolle in France, at the end of the 19th century, patented a windmill that pumped water. It could generate electricity, but water was more needed.

The device was strange, but commercially successful. Some of them have survived to this day, and some even work.

The unique thing about the Bolle windmill was that it had two rows of blades. Moreover, one of them was a stator; it had more blades and was located on the windward side. That is, the wind first blew it, and then turned the rotor.

At the end of the 20th century, this design received a new impetus for development, and became known as the DAWT (Diffuser-Augmented Wind Turbines) concept.

With this design, the inventors hope to circumvent the law of the German physicist Betz, who a hundred years ago proved that no more than 16/27 of the energy (about 59%) can be extracted from the wind.

Several experimental models of DAWT wind turbines have been installed on the coast of Japan and in other countries with strong winds.

It was noted that the power of the installation is increasing, but the loads on the structure are also becoming critical. Among the positive effects, a sharp decrease in noise and a decrease in radar interference are noted.

But the Dutch did not rest on this; the SheerWind company came up with and even implemented the INVELOX project, in which the Venturi effect actually manifested itself.

According to this postulate, the speed of an elastic flow increases if it flows through a bottleneck. Several similar devices are being tested in the USA and Holland.

At a certain moment, it was noticed that an air flow disturbance occurred behind the rotating blades of the windmill. This has a very bad effect on the strength of the entire structure. And in 1992, a wind generator with two blades rotating in opposite directions was patented.

An important advantage of this design was the damping of sympathetic vibrations. Musicians are familiar with this phenomenon, for example the A string at 440 Hz will cause the E string to resonate at 330 Hz since they have an overtone of 1320 Hz (3rd harmonic of A and 4th harmonic of E). But despite their attractiveness, these wind generators have not yet been commercially sold.

However, about 15 years ago, engineer Douglas from the USA decided to move the blades further away from the generator nacelle.

And 10 years later, an Indian and a Chinese, also NASA engineers, came to the conclusion that it is possible to place not two rows of blades, but much more!

In 2022, they demonstrated a 12 m long working installation, which had 12 rows of blades. Moreover, they all turned a common rotor. The efficiency increased significantly, and the wind generator began to start at lower wind speeds.

And restless minds are trying to experiment with the shape of the blades. Of the many wonderful forms, the twisted-wrapped blade, presented in 2010 at the wind energy innovation exhibition in France, deserves the most attention.

How to make it yourself

A windmill of this design will not be difficult to make for a person who knows how to work with hand tools and has a little knowledge of electrical engineering.

To make it you will need:

Sheet metal (any, 0.8–0.9 mm thick) – for the manufacture of blades;
Strip steel 40x40 mm (or other section);
Steel pipe, diameter 25 mm;
Automotive axle shaft (the brand of the car is not important) with bearings included;
Steel corner (profile);
Pulleys of different diameters – 2 pcs.
Car generator.

4 blades with overall dimensions of 1000x800 mm are made from sheet metal, which are fastened together with strip steel in the shape of a drum (the blades are directed from the center of the circle along the radii to the outer diameter). A mast is made from a steel pipe, which on one side is fixed to the automobile axle shaft, and on the other side the blades assembled in the form of a drum are attached to it. The axle shaft, with its corresponding bearings, is mounted on a metal support structure, which is made of any shape and from available materials.

The two main conditions for the manufacture of a metal structure are:

Stability under wind loads;
Tight fit of axle bearings.

To increase the number of revolutions, you can use a belt drive by installing a pulley of a larger diameter on the lower axle shaft, and a smaller one on the generator. The generator can be selected from a car.

Bladeless wind turbines

After some thought, the inventors came to the conclusion that, in principle, a wind generator could be without blades! The idea is absurd! How can there be a windmill without blades? But she was the progenitor of windmills. However, prototypes of such models were invented, manufactured and tested. And some of them are even ready for commercial release.

The most amazing of them is the ion wind generator. Its distant ancestor can be considered the “Kelvin Dropper,” which the great scientist invented in 1867.

They decided to install this system horizontally so that drops of water would be carried by the wind. The advantage over a conventional wind generator is that the ionic model:

absolutely silent;
nothing moves in it;
it only collects electrostatic charge from the water droplets.

Perhaps the incentive for the Dutch innovators was to legally visit the legendary cafe shops in Amsterdam, because it is also very quiet there and nothing moves. However, they made several working prototypes of ionic wind generators, which they installed in Rotterdam.

One was even built into the letters O on the roof of the building

The efficiency of the ion wind generator is low, only 7%. In the future they hope to increase it to 27%, but there’s nothing to break there! Such a bright prospect contributed to the creation of a colossal project. It will be a huge donut-shaped building in which guests will relax and laze around. Nothing will move there, and the wind will bring charged particles of water. In Russia such a project would be called “Kremlin”, and in the Netherlands it is Windwheel.

After Spain followed the Dutch path in the field of liberalization of human vices, their inventors began to take such long strides that the flight of imagination could not keep up with them.

For example, that old lady in the background clearly thinks that she is hugging a souvenir from a sex shop, but this is a mistake! This is the innovative Vortex Tacoma wind generator.

Although it would be more correct to call it a wind vibrator.

As conceived by Vortex Bladeless SL engineers, this elastic rod will oscillate in the wind, and thanks to a clever device with neodymium magnets, it will be able to generate electricity.

They built several real prototypes and tested them in urban and rural environments, with mixed results.

On the one hand, the 2.75 m tall Vortex Tacoma model produces only 100 watts of power. But there is nothing to break, there is no need for adjustment and orientation to the wind, this miracle works silently. In general, a hundred and so, trembles in the wind, and generates, generates, generates...

The prototype has been tested, and commercial sales are scheduled to start in 2022. The most effective Vortex Atlantis model.

The height of this wind vibration generator is 10-12 m, the output power is 1 kW.

The French also have a similar project, in which nothing spins, but it is powered by the wind, which means it is a wind generator. The project is called Saphonian.

We can roughly compare it with the Spanish project. Only in Saphonian the wind is captured by a work surface in the form of a specially designed plate.

It continuously changes the angle of inclination, and the generator located on the back side converts these oscillatory movements into electricity.

The French are silent about the power and time to enter the market, but with such a model they hope to escape the restrictions of the Betz law, because their design does not include blades.

Third generation wind turbines

The turbine principle in the design of wind turbines is considered the most effective. Such devices demonstrate relatively high efficiency and are capable of starting rotation at low wind speeds. This direction is considered to be the most promising wind energy industry, and wind generators created according to this principle are classified as models of the new, third generation.

At the same time, there are still very few industrial developments. Basically, they are represented by foreign models with low performance and high prices, which puts a serious barrier between them and consumers. At the same time, this situation stimulates the growth of independent developments, many of which can radically change the situation around wind energy as a whole.

Moreover, if at first random people were engaged in the manufacture of such devices, now among amateur designers there is a large percentage of professionals who have special training and are capable of accurately calculating their projects. Therefore, the quality of such homemade products often exceeds industrial designs.

The current situation is such that industrial-scale developments carried out by foreign companies are focused more on high productivity, while the inventions of domestic masters serve to create the ability to provide electricity to a small area - a private house, estate, expedition, etc., which means others prices and terms of use.

Air wind generators

After World War II, the Italian Massimo Ippolito decided to harness wind energy through kites. But there was no technology for this yet, and the idea was shelved. But towards the end of the 20th century, it began to acquire its real embodiment. By this time, a map of the Earth's high-altitude winds had been created, and it turned out that it was over Europe and Patagonia, at altitudes from 0.8 to 10 km, that there were always powerful air currents.

Italian Master of Engineering L. Foggiano wrote a thesis on the capabilities of the Kitegen wind generation system.

From the calculations it followed that if you build a ring generator with a diameter of 1.6 km and launch 6 dozen high-altitude automatic kites, they will be able to spin this giant wheel at a speed of 15 rpm. Which makes it possible to generate 1 GW of electricity, i.e. power comparable to a nuclear power plant.

But for now we have focused on small projects, capacity up to 300 MW,

Its development has been completed, and small prototypes with a performance of 150-200 kW have already been tested in Italian Sardinia.

Compared to conventional wind generators of similar power, the Italian project Kitegen is an order of magnitude ahead of its competitors.

However, the Americans are not lagging behind. They developed their project X Development LLC, which is already an all-metal airframe.

To launch, energy is required, which is transmitted through a cable combined with a cable, but after reaching the calculated height, it begins to soar like a kite in the oncoming air currents.

And small generators on the wings generate electricity, which is transmitted via cable to the base. It (the base) can be either land-based or sea-based.

The prototype is already being tested from 2022. No particular difficulties were noticed; the calculated generation capacities were achieved.

But the pedantic Germans have advanced the furthest; they have truly fantastically bold projects and, by the way, have already been translated into reality. Not only that, they are ready for sale! The concept of a German airborne flying generator from Enerkite is called “EK 30”.

The operating principle of EnerKítes is cyclic, two-stage:

Stage 1 “Working phase” - the wing flies across the wind with maximum rope tension. The rope is released and pulls the generator winch away from the base.

Stage 2 “Return phase” - the wing interrupts the eighth approach, glides quickly and with little effort back to the starting altitude, then the cycle is repeated.

The full cycle takes about a minute. The first stage requires about 7-12% of the energy received. Unlike classic flying wind turbines, electrical energy is generated on the ground. From there the wing is also controlled so that only what belongs in the air moves in the air. All work is done automatically.

The secret of generation is in the patented cable winding drum.

There is also a more serious model “EnerKíte EK200” - a portable aviation wind turbine for decentralized and uninterruptible power supply. It provides clean and reliable electricity at prices ranging from 7 to 12 eurocents/kWh. Housed in a 20 pound container, weighs 12.5 tons. Working height up to 300 m. Rated power 100 kW. Temperature range from -20 to +50˚C.

The EnerKíte EK200 wind generator can cover the own needs of small businesses. It replaces expensive diesel electricity in undeveloped regions.

Review of the best brands and installations

The Russian market of wind generators offers both reliable, relatively inexpensive devices from domestic brands, and models of wind turbines from foreign manufacturers that vary in functionality.

To decide on the choice of installation for your home, you need to compare the characteristics of different units.

No. 1 - wind generators Condor Home (Russia)

A series of wind turbines for home use includes devices with a power of 0.5-5 kW. They can serve as the main source of electricity or additional.

Condor Home stations are adapted for operation in low temperature conditions and are capable of producing energy even in low winds.

Depending on the model, the generator housing is made of plastic or cast aluminum, the blades are made of fiberglass. There is an effective dual braking system. The mast is composite, guyed, and has a height of 8-12 m.

To install these units you need a pile or concrete foundation.

Condor Home home wind generators are completely ready-made products that do not require special knowledge or technical skills to operate. The devices are designed for electrification of both free-standing buildings and small settlements as part of wind power plants

The basic package includes a mast and guy ropes, a generator, a rotor and blades, a charge controller, and fasteners.

No. 2 - Falcon Euro mini-power plants (Russia)

They are high-tech vertical-axis wind generators with a power of 1-15 kW. They are used for primary/backup power supply to consumers remote from power lines.

Can be used as part of a complex with solar panels and a fuel generator.

Windmills are equipped with powerful neodymium magnets. The starting wind speed for starting the installation is 1.5 m/s, the nominal speed is 11 m/s.

The installed aerodynamic brake helps limit wheel speed. The declared service life from the manufacturer is 20 years, the factory warranty on the mini-power plant is 36 months.

Falcon Euro wind generators are reliable in operation and unpretentious in maintenance. With the help of devices of this series it is easy to solve the problems of power supply of local and island facilities

The basic Falcon Euro installation kit includes several functional elements: a wind wheel, a generator and controller, a mast, and embedded parts. The inverter installation and batteries are selected separately.

No. 3 - wind turbines Sokol Air Vertical (Russia)

Small wind power plants of this brand can provide electricity to both small cottages and medium-sized enterprises. For domestic use, SAV devices with a power of 0.5-15 kW are produced.

They are characterized by high efficiency in light winds, operate smoothly at low and high temperatures in the range from -50 °C to +50 °C, are characterized by low noise levels and resistance to external influences.

The generation of electricity by Sokol Air Vertical units does not depend on wind direction. Vertical-axial installations operate in automatic mode without maintenance personnel.

The design provides an electromagnetic and aerodynamic braking system to limit the speed of the wind wheel.

The blades are made of reinforced polyester or aircraft grade aluminum (depending on the model) and have a self-unwinding profile. The generator is a multi-pole three-phase generator with excitation from permanent magnets.

Sokol Air Vertical wind turbines produce rated power at 7-8 m/s, which allows their use in regions with low average annual wind speeds

The basic package of a wind power plant includes: a wind turbine with a battery charge controller, a mast with guys, and an installation kit. The inverter and batteries are selected separately according to the technical specifications.

No. 4 - wind generators Energy Wind (Russia)

Buyers have access to single- and three-blade models of universal-use products with a power of 1-10 kW. These wind turbines are perfect for creating projects to provide electricity to private residential buildings and cottages.

Energy Wind units are based on durable blades made of reinforced fiberglass, painted with auto enamel, and a reliable air flow exhaust system. These units with a horizontal axis of rotation operate stably at temperatures from -40 to +40 degrees Celsius.

The minimum operating wind speed is 2 m/s, at some blade positions - 3 m/s, the recommended mast height is 8-20 m. The average service life of Russian brand installations is 25 years, the official warranty from the manufacturer is 3 years.

Energy Wind wind generators do not require constant care or maintenance, which contributes to the rapid reinvestment of invested funds

The basic equipment of the installations includes a permanent magnet electric generator with a mounting unit for the mast and a rotating mechanism, blades, and a set of fasteners for assembling a wind turbine.

The mast, as well as the controller, inverter and batteries for storing electricity must be purchased separately.

No. 5 - Altek EW wind turbines (China)

Type of wind turbines – with a horizontal axis of rotation. Devices with a rated power from 1 kW to 10 kW are ideal for solving the problems of power supply to country houses and cottages.

The protective casing of Altek EW wind turbines is made of aluminum alloy, which significantly facilitates the design. The functional metal parts of the generator are coated with silicon for heat resistance.

The blades are made of fiber-reinforced plastic. The starting wind speed for launching household units of the Chinese brand is 2.5 m/s, the nominal speed is 12 m/s.

Altek EW wind generators are one of the most affordable devices for generating electricity that are presented on the modern alternative energy market

The basic package includes blades, a generator and a controller. The remaining functional elements for the windmill must be purchased.

What to look for when buying a wind turbine

It is important to consider the height of the mast. The higher the windmill is, the more wind it can “catch”. Wind speed increases depending on height, so even in not particularly windy areas, a wind turbine can operate successfully if the mast is high enough. The standard mast height is 10 meters. With each subsequent ten meters, the power of the wind flow will increase by one and a half times.

Pay attention to the following factors:

actual volumes of electricity that a wind turbine can generate under the conditions of your site;
the relevance of the selected model, how long it has been in production and how well other users rated it;
warranty periods and maintenance intervals;
estimated period of use of the wind power plant;
degree of complexity of installation and maintenance.

Comments:

Uncle Vova

I assembled a vertical windmill from an oil drum, it worked until winter. The bearings in the generator are covered because... In the spring, it only produced creaking and grinding noises, but no electricity. You need very good bearings.

Evgen

I’ve been hooked up to a regular Zhiguli generator and it’s been working fine for three years now. It illuminates the street, and in the summer I connect a mole repeller to it. It seems to me that the problem is not in the bearings, but in the tightness.

Bogdan

Evgen, of course, the problem is tightness, but if you install seals that will not allow moisture to pass into the bearing, the efficiency of the entire structure will decrease. So I’m thinking, what should I do? Should I leave everything open or seal it as much as possible?

Igor

People, what are you talking about? Do you want to protect your car generator with something else? Yes, it is designed to work in such extreme conditions that a windmill (even one made from a barrel) is a vacation for it! There is always water, dirt and snow under the hood and the temperatures are the most extreme. The fact that Uncle Vova’s bearings broke on his auto-generator means that they had been broken for a long time, and were waiting for the “right moment” to announce it.

Vladimir

Bearings must be taken from 18 GPP, or from France, Sweden. I think SKF bearings with original lubrication (hub) have been working for 12 years, and there is zero noise.

Madi

The most advanced vertical-axis wind generator https://www.facebook.com/madiz.zhakypov/posts/10154799110278007

Virtual Private Server

That is, it turns out that people are simply being deceived by saying that vertical wind generators are more efficient in low winds. There are also Daria rotors, they are faster and larger than KIEV, but they have problems with starting in low winds and uneven thrust, and their calculation is very complicated.

Michael

One thing is clear: the windmill must be installed in “batteries” of three to six... pieces. Then it will make sense. At least heat the water.

The most common mistakes when purchasing

Dissatisfied consumer reviews can be explained by the desire to get a high-quality product for practically nothing, and to save on services and installation work. Therefore, many people purchase relatively cheap equipment without particularly studying the technical characteristics and other nuances.

Since all types of alternative energy have a fairly high cost, and a wind generator is no exception, sellers are doing their best to sell this product to the buyer. When the company manager explains to his client that with a blade diameter of 4 meters he can get a power of 7 kW, for some reason he does not specify in what wind.

The power of the wind generator will be proportional to the cube of the wind speed and the diameter of the wind wheel. That is, for regions with an average wind speed of 6 m/s, the power will be W6=4*(6*6*6)= 864 W. A satisfied client does not suspect that the power of his system will actually be 8 times less than promised.

Thus, when choosing a wind generator, you should pay attention to: its power, rated wind speed, blade diameter, and choose the inverter wisely (with maximum efficiency and minimum no-load current).

Advantages and disadvantages of wind power plants for home

Like any other type of equipment, wind power plants have both advantages and disadvantages. To decide to buy this device, it is advisable to weigh its strengths and weaknesses.

The popularity of using wind power plants is due to a large number of advantages

Why is it profitable to buy a wind generator (220V) for a private home:

There are no additional costs, since the device does not require fuel to operate.
There is no need for constant monitoring. The structure generates electricity on its own every time the wind blows.
A relatively silent and completely environmentally friendly way of generating electricity.
The device can be used in almost any climatic conditions.
Part wear is minimal.

Installing a wind generator for a home is accompanied by the following disadvantages:

the cost of purchasing equipment pays off in 5-6 years;
relatively low efficiency indicator, which is reflected in power;
high price of wind generators;
to compensate for the device’s inactivity on windless days, additional equipment is required: a generator and a storage battery (the cost of these elements is very high);
in some modes, windmills for home use infrasounds (the same thing happens if the equipment is installed incorrectly);
Regular preventative maintenance is required;
a hurricane can seriously damage equipment.

Depending on the power of the device and the wind map of the area, a windmill can provide electricity to both a small country house and a large country cottage

Helpful advice! You definitely need to calculate the profitability before buying a wind generator for your home; the price of the equipment may be too high, and the cost of purchasing it will not pay off. To do this, you need to calculate the average power of the house (the power of all electrical appliances is taken into account), evaluate the area where the equipment will be installed, and find out the number of windy days per year.

Using a wind generator for low winds - Onipko rotor