Protecting the windmill from strong winds with your own hands. Windmills can protect against hurricanes (video)

The increase in user interest in alternative sources of electricity is understandable. The lack of opportunities to connect to centralized networks forces the use of other methods of providing housing or temporary residences with electricity. The share is constantly growing, since the acquisition of an industrial design is a very costly business and is always quite effective.

When creating a windmill, one should take into account the possibility of heavy gusts of wind and take appropriate measures to protect the structure from them.

Why do you need protection from strong winds?

Wind turbine operation designed for a certain wind force. Usually, average indicators typical for a given region are taken into account. But when the wind flow increases to critical values, which sometimes happens in any area, there is a risk of device failure, and in some cases - complete destruction.

They are equipped with protection against such overloads either by current (if the permissible voltage value is exceeded, an electromagnetic brake is activated) or by rotation speed (mechanical brake). Homemade designs also need to be equipped with similar devices.

Impellers, especially those equipped with, at high speeds of rotation, begin to act on the principle of a gyroscope and retain the plane of rotation. Under such conditions, the tail cannot do its job and orient the device along the flow axis, which leads to breakdowns. This is possible even if the wind speed is not too high. Therefore, a device that slows down the speed of the impeller is a necessary design element.

Is it possible to make a device with your own hands?

Making a fixture is quite possible. Moreover, it is an absolute necessity. Brake device should be provided at the design stage of the windmill. The operating parameters of the device must be calculated as carefully as possible so that its capabilities are not too low compared to the actual needs of the structure.

First of all, you need to choose a way to implement the braking device. Usually, simple and trouble-free mechanical devices are used for such designs, but electromagnetic samples can also be created. The choice depends on which winds prevail in the region and what is the design of the windmill itself.

The easiest option is to change the direction of the rotor axis, which is done manually. To do this, you only need to install a hinge, but the need to go outside in strong winds is not the best solution. In addition, it is not always possible to manually stop, since at this moment you can be far from home.

Operating principle

There are several mechanical ways to brake the impeller. The most common options for horizontal windmill designs are:

• rotor deflection from the wind with the help of a side blade (stopping by the folding tail method);
• rotor braking by means of a side blade.

Vertical structures are usually braked by means of weights hung on the outer points of the blades. With an increase in the rotation speed, under the action of centrifugal force, they begin to put pressure on the blades, forcing them to fold or turn sideways to the wind, which causes the rotation speed to decrease.

Attention! This method of braking is simple and most effective, allows you to adjust the speed of rotation of the impeller, but is applicable only for vertical structures.

Tail folding defense method

A device that steers away from the wind by folding the tail allows you to smoothly and quite flexibly adjust the speed of rotation of the rotor. The principle of operation of such a system is to use a side lever installed in a horizontal plane perpendicular to the axis of rotation. The rotating impeller and arm are rigidly connected, and the tail is attached through a spring-loaded swivel joint operating in a horizontal plane.

At nominal values ​​of wind force, the side arm is not able to move the rotor to the side, as the tail directs it into the wind. When the wind increases, the pressure on the side blade increases and exceeds the force of the spring. In this case, the rotor axis turns away from the wind, the impact on the blades is reduced and the rotor slows down.

other methods

The second method of mechanical braking is similar in design, but the side blade acts differently - when the wind increases, it begins to put pressure on the rotor axis through special pads, slowing down its rotation. In this case, the rotor and tail are mounted on the same shaft, and the swivel with a spring is used on the side lever.

At normal wind speeds, the spring holds the lever perpendicular to the axis, when strengthened, it begins to deviate towards the tail, pressing the brake pads to the axis and slowing down the rotation. This option is good for small blade sizes, since the force applied to the shaft to stop it must be quite large. In practice, this option is used only at relatively low wind speeds; with squall gusts, the method is ineffective.

In addition to mechanical devices, electromagnetic devices are widely used. As the voltage rises, a relay starts to operate, attracting the brake pads to the shaft.

Another option that can be used for protection is to open the circuit when too high voltage occurs.

Attention! Some methods only protect the electrical part of the complex without affecting the mechanical elements of the structure. Such methods are not able to ensure the integrity of the windmill in the event of sudden heavy winds and can only be used as additional measures, acting in tandem with mechanical devices.

Scheme and protection drawings

For a more visual representation of the principle of operation of the braking device, consider a kinematic diagram.

The figure shows that the spring in the normal state keeps the rotating assembly and tail on the same axis. The force created by the wind flow overcomes the resistance of the spring when the speed increases and gradually begins to change the direction of the rotor axis, the wind pressure on the blades decreases, due to which the rotation speed drops.

This scheme is the most common and effective. It is easy to perform, allows you to create a device from improvised materials. In addition, setting this brake is simple and comes down to selecting a spring or adjusting its force.

Attention! The maximum angle of rotation of the rotor is not recommended to be more than 40-45°. Large angles contribute to the complete stop of the windmill, which then starts with difficulty in uneven squally winds.

Calculation procedure

Calculation of the braking device pretty complicated. It will require various data, which is not easy to find. It is difficult for an unprepared person to make such a calculation, the probability of errors is high.

However, if self-calculation is necessary for any reason, you can use the formula:

P x S x V 2 = (m x g x h) x sinα, where:

• P is the force applied to the screw by the wind flow,
• S is the area of ​​the propeller blades,
• V - wind speed,
• m - mass,
• g - free fall acceleration (9.8),
• h is the distance from the hinge to the spring attachment point,
• sinα - angle of inclination of the tail relative to the axis of rotation.

It should be borne in mind that the values ​​obtained from independent calculations require a correct interpretation and a complete understanding of the physical essence of the process occurring during rotation. In this case, they will not be correct enough, since the subtle effects that accompany the operation of the windmill will not be taken into account. However, the values ​​calculated in this way will be able to give the order of magnitude required for the manufacture of the device.

The process of creating a wind turbine is accompanied by a lot of expenses and requires a variety of actions, which in itself forces the structure to be protected as much as possible from the possibility of destruction. If there is a foreseeable danger of destruction or failure of the complex, then the creation and use of protective devices should not be neglected in any case.

The maximum wind speed allowed for the operation of a wind generator with your own hands is 20-25 meters per second. If this indicator of the air flow rate is exceeded, the operation of the station must be limited. Moreover, this should be done even if the windmill is of the slow-moving type.

Of course, it is unlikely that a homemade windmill will be able to spin up to such a speed that it will collapse completely. But there are many cases in history when enthusiasts built their own wind turbines, but did not provide any protection from strong winds. As a result of this, even the strong axles of the automobile generator could not withstand the entire load and broke like matches. Therefore, if the wind is strong, then the pressure on the tail of the plumage increases significantly, and in the event of a sharp change in the direction of the air flow, the generator will spin sharply.

Taking into account the fact that at high wind speeds the generator impeller is able to rotate fast enough, the whole structure turns into a gyroscope that resists any turns. This causes significant loads to be concentrated on the generator shaft between the wind wheel and the frame.

Among other things, a wheel with a diameter of 2 meters will have high aerodynamic drag. With a strong wind, this threatens with high loads on the mast. And therefore, for a more reliable and long-term operation of the wind generator, it is worth worrying about protection.

The easiest way to use for such purposes is the so-called side shovel. This is a very simple device that can significantly save money, effort and time spent on the construction of the station.

The operation of such a device lies in the fact that with a working wind at a speed of 8 m / s, the wind pressure on the structure is lower than the pressure of the protection spring. This allows the generator to operate normally and keep upwind with the help of the feathers. To prevent the windmill from collapsing in operating mode, there is a stretch between the side shovel and the tail. But with a strong wind flow, the pressure on the wind wheel exceeds the force of the spring pressure, as a result, the protection is triggered. When the generator begins to fold, the wind flow hits the wind generator at an angle, which seriously reduces its power.

At very high wind speeds, the protection completely folds the generator, which lies parallel to the direction of the wind flow. As a result, the operation of the windmill almost completely stops. It is worth noting that in this case, the empennage tail is not rigidly attached to the frame, but has the ability to rotate. The hinge, which is used in this case, must be made of high-strength steel, and its diameter must not be less than 12 millimeters.

The idea, the basic principle of a mechanism or device, is important for a home master. He will think out the details himself, based on his understanding of the effectiveness of the design, the availability of the necessary materials and components.

Wind turbines for a private house, for all their merits, are still exotic and expensive equipment in Russia. The price of a factory-made device with a capacity of 750 watts starts from 50 thousand rubles, for the purchase of a wind generator for 1500 watts you will be charged more than 100 thousand rubles. Masters who made more than one home mechanism with their own hands could not pass by the opportunity to design a home-made wind generator. Their experience, knowledge and advice are used in the description offered for self-execution of the windmill.

The main difference between a wind generator and other generation systems is that it constantly generates energy when air moves at a speed starting from 2 m/s. The continental climatic conditions of Russia determine the stable presence of such a wind in almost the entire territory.

Wind turbines, to a greater or lesser extent, provide independence from power supply networks. This independence is provided by the battery pack. Homemade wind turbines are easy to make with your own hands, are small in size and easy to install.

Design choice. Main components and mechanisms

The hands of craftsmen made many mechanisms that use wind energy. Homemade wind turbines are divided into groups. These are horizontal and vertical wind generators. The devices differ in the direction of the axis of the wind wheel. For vertical wheels, the blades work half a turn of the wheel against the wind flow.

Horizontal wind turbines lose rotational speed due to a change in wind direction. As a rule, home craftsmen take as a basis a wind wheel with a horizontal axis of rotation. It is important to consider that in the entire history of man's technical solutions, it is difficult to find the use of vertical axis windmills, and horizontal windmills flap their wings for centuries.

General scheme of the wind generator

1. wind wheel blades;
2. generating device;
3. generator shaft frame;
4. side blade protection against strong winds;
5. current collector;
6. knot fastening frame;
7. Swivel knot;
8. shank;
9. mast;
10. clamps for stretch marks.

Table 1. Specifications

Wind wheel blades

Do-it-yourself blanks are made from polyvinyl chloride (PVC). Plastic blades are easy to process, insensitive to a humid environment. The pressure pipe SDR PN 6.3 (diameter 160 mm, wall thickness 4 mm, length 1000 mm) is used as a blank.

The calculation of the shape of the blade is quite complicated. We use a template (Figure 2, dimensions in mm), already calculated by specialists. The template is cut out from a thick paper sheet, applied to the pipe and a contour is drawn. Do-it-yourself blanks are cut with a conventional saw or electric jigsaw.

You will receive 6 blank blades. To increase the efficiency of the wind wheel, reduce the noise level, it is necessary to grind off all the corners and grind the surfaces of the products. It is advisable to process all the workpieces at once, clamping them with clamps or a bolt through a working hole outside the workpiece contour.

The blades are attached to the bike motor body through a steel coupling (thickness 10 mm, diameter 200 mm). Six steel strips with a width of 12 mm and a length of 300 mm with holes for attaching the blades are attached to the coupling by welding.

The assembled wind wheel is carefully balanced. Spontaneous rotation is not allowed. Balancing is carried out by grinding the material with a file from the end of the product with your own hands. Windwheels are driven into one plane of rotation by bending the steel fastening strips.

generating device

An electric motor for a bicycle with parameters of 24 V 250 W is used as a generator. A similar product costing from 5 to 15 thousand rubles. can be easily ordered via the Internet.

Table 2. Specifications of a 250 W bike motor

The coupling is connected to the motor body with bolts through the holes for fastening the spokes. It is quite possible to choose a generator at a more adequate price, as an example, an electric motor with permanent magnet excitation from a tape drive of an electronic computer. Device parameters 300 W, 36 V, 1600 rpm.

Generators with the necessary characteristics can be made by hand from an automotive device of a similar purpose. The stator is not subject to changes, the rotor is equipped with neodymium magnets. Reviews of the masters about such alterations of the generator are positive.

Installing the generator on the frame

The bicycle motor, when used for its intended purpose, operates under significant loads. The parameters of the calculated strength of the motor satisfy the conditions for using the product as a homemade windmill generator. The generator shaft is attached through a threaded connection to a do-it-yourself frame made of aluminum alloy 10 mm thick. The bed is bolted to the frame.

The dimensions of the bed, the placement of the holes are determined by the dimensions of the selected generator. For the manufacture of the frame, a channel section with a section thickness of 6-10 mm is selected. The structural dimensions of the frame depend on the dimensions of the turning unit.

Swivel Assembly and Current Collector

Rotation of the wind generator into the wind, its mounting on the mast, transmission of electricity to the control unit provides a turning unit.

1. dielectric axis of current collector;
2. contact node;
3. current collectors;
4. frame;
5. Weld;
6. body of the rotary device;
7. rolling bearings;
8. rotary device shaft;
9. mast;
10. electric wires.

From the drawing and photo, it is easy to understand the design of the rotary assembly and make the mechanism with your own hands, the material for the blanks is steel pipes. It is better to use roller bearings, as they are more resistant to axial loads.

The design of the current collector is no more complicated.

The contact assembly is made of a copper bar of square section with a side of 10 mm. An insulated copper wire with a cross section of at least 4 mm is soldered to them.

Strong wind protection

The speed of the wind flow, at which home-made wind turbines operate in nominal mode, is 8 m / s. Higher winds require protection against damage to the product. A reliable protection device is the do-it-yourself side blade mechanism.

At a nominal flow rate of 8 m/s for products such as homemade wind turbines, the pressure on the side blade is lower than the tensile force of the protection spring. The wind generator works and is guided downstream by the tail unit. When the flow pressure on the wind wheel increases, the blade spring is activated. The wind wheel turns, reducing the generated power. High flow rates, through pressure on the side blade, completely turn the wind wheel, setting it parallel to the direction of flow, energy generation stops.

Wiring diagram

The electrical circuit is assembled from the following components:

Generator (bike motor);

control unit;

battery;

Power and switching wires.

The given circuit diagram is being finalized taking into account the fact that the control unit must provide:

Charging the battery by limiting the charging current to acceptable values;

Connection to the generating device of the ballast load at the end of the charging of the battery, excluding the transition of the wheel to the wheel;

Electric braking mode, stopping the wind generator.

wind turbine mast

The mast for the wind generator can be metal pipes with a diameter of 100 mm and above. The minimum mast height is 6 meters in open areas. If there is no open area, the height of the mast is increased by 1 m against the height of obstacles within a radius of 30 m from the base of the tower.

The weight of the windmill assembled with the mast is quite significant, which requires the use of a counterweight, which will facilitate the installation and lowering of the mast, repair work. The greater the height of a self-made mast, the greater the impact of the wind flow on your homemade nodes. Reviews of the masters recommend installing extensions every 5.5 m of mast height. Homemade stretch marks are attached to the ground with anchors along a radius of at least 50% of the height of the mast.

The photo shows a finished homemade wind generator. A rotating wind wheel, a generator, the electrical voltage generated by it and changing weather conditions make homemade products dangerous mechanisms. Exercise extreme caution when operating and repairing a DIY product. Be sure to securely ground the mast.

How to protect a wind generator from a strong wind, because, for example, during a hurricane, the blades can easily fail and fly off. Or, even worse, the mast will not withstand, for example, it will tear off the stretch marks and the wind generator will collapse, sweeping away everything in its path of fall. Of course, for small windmills with a propeller diameter of up to 1.5m, protection against strong winds is not particularly relevant, since there is no such huge pressure on the propeller. But for large windmills, wind protection is obligatory, a large propeller during a hurricane experiences tremendous pressure and here not only the blades can fly off, but also steel cables can be torn or uprooted from the ground. Well, in general, I think it is clear that without protection, especially in the vicinity of people and buildings, it is better not to install a windmill, once a year at least hurricanes still happen.

Storm protection has already been installed in factory wind generators; for small wind turbines, as a rule, an electric brake is used. That is, when a certain speed is reached, the generator phases are pulsed by the controller and the screw loses speed, dropping power. Or protection is not provided at all and the controller slows down by shorting the generator only when the voltage exceeds a certain value, for example 14 volts for a twelve-volt system. For home-made small windmills, home-made controllers (ballast regulators) are often made, which also slow down the windmill when the voltage is exceeded, slow down by turning on an additional load in the form of light bulbs or nichrome spirals, tenns. Or they buy ready-made controllers where everything is already there and braking and forced stop of the windmill.

Large windmills, in addition to the controller, must also have mechanical protection, since large propellers take off huge power in strong winds and go "over the top" and even a complete circuit of the generator does not stop the propeller. In factory windmills, protection is usually made by turning the tail and the screw turns away from the wind. The "wind catchers" are based on the classic method of removing the propeller from the wind by folding the tail, which has long become a classic. This scheme will be discussed further.

Strong wind protection scheme

Defense works like this. When there is no wind and the propeller is not turning, the tail is deflected to its 45 degrees and hangs to the side. With the advent of wind, the propeller turns and begins to rotate, and the tail turns into the wind and aligns. When a certain wind speed is exceeded, the pressure on the propeller becomes greater than the weight of the tail, and it turns away, and the tail folds. As soon as the wind weakens, the tail unfolds under the weight again and the propeller becomes in the wind. So that when folding the tail does not damage the blades, a limiter is welded.

Wind turbine protection principle

Here the main role is played by the weight of the tail and its length and plumage area, as well as the distance by which the axis of rotation of the propeller is shifted. There are formulas for the calculation, but for convenience, people wrote Excel spreadsheets on which everything is calculated in two clicks. Below are two plates taken from the forum windpower-russia.ru

Screenshot of the first plate. Enter the data in the yellow fields and get the desired length of the tail and the weight of its tip. The tail area is by default 15-20% of the swept propeller area.

Tail unit calculation

The second plate is slightly different. Here you can change the horizontal angle of the tail. It is considered as 45 degrees in the first table, but here it can be changed in the same way as the vertical deviation. Plus, a spring is added, which additionally holds the tail. The spring is installed as a resistance to tail folding for faster return and to reduce the weight of the tail. The tail area is also taken into account in the calculation.

Download - Calculation of the tail unit 2.xls

Tail unit calculation 2

Also, the weight of the tail and other parameters can be calculated using these formulas

Fa - axial force on the screw.

According to Sabinin Fa=1.172*pi*D^2/4*1.19/2*V^2
according to Zhukovsky Fa=0.888*pi*D^2/4*1.19/2*V^2,
where D is the diameter of the wind wheel, V is the wind speed;

X - the desired offset (offset) from the rotary axis to the axis of rotation of wines;
m is the mass of the tail;
g - free fall acceleration;
l is the distance from the finger to the center of gravity of the tail;
a - angle of inclination of the finger.

For example, a screw with a diameter of 2 meters, wind speed at which the tail should fold = 10 m / s

We consider according to Zhukovsky Fa \u003d 0.888 * 3.1415 * 2 ^ 2 / 4 * 1.19 / 2 * 10 ^ 2 \u003d 165N

Tail mass = 5 kg,
distance from the finger to the center of gravity of the tail = 2m,
finger angle =20 degrees

X=5*9.81*2*sin(20)/165/3.1415*2=0.129 m.

Also a more understandable calculation of the mass of the tail

0.5*Q*S*V^2*L1*p/2=M*L2*g*sin(a), where:
Q - air density;
S - screw area (m ^ 2);
V - wind speed (m/s);
L1 - displacement of the axis of rotation of the wind head from the axis of rotation of the propeller (m);
M - tail mass (kg);
L2 - distance from the axis of rotation of the tail to its center of gravity (m);
g - 9.81 (gravity);
a - angle of inclination of the axis of rotation of the tail.

Well, that's probably all, in the printsepe of Excel tables it is quite enough for the calculation, although you can use the formulas. The disadvantage of such a protection scheme is the yaw of the propeller during operation and a somewhat belated reaction to a change in wind direction due to the floating tail, but this does not particularly affect energy generation. In addition, there is another option for protection by the "floating" of the screw. The generator is placed higher and it capsizes, while the screw, as it were, lies down turning away from the wind, in this case the generator props up the shock absorber.