Fans are the backbone of any ventilation system. Such devices are widely used in everyday life, they are indispensable in many areas of human activity. Also, devices are actively used in automotive technology, in computers, in welding machines. In our article, we will talk about what types of fans exist, learn about design features, purpose, consider the principle of operation of each type of device. Based on this, you can find out which type is best to apply in a particular case.
Main features of fans
Fans are mechanical type devices that are designed to supply, move or exhaust gas and air masses. Air circulates due to the fact that there is a pressure difference between the inlet and outlet of the installation. Fans are used almost everywhere. They are simply indispensable in the manufacture of supply and exhaust ventilation, in stoves,air conditioners.
Fans are used only with those gases whose compression ratio is not more than 1, 15. Moreover, the pressure difference between the inlet and outlet is not more than 15 kPa. If you need to increase this figure, you will have to use a compressor. The main criteria for fans can be identified:
- The principle of operation and design of the device.
- Mounting method.
- Features of functioning and purpose.
- Option for driving the impeller from an electric motor.
You can also highlight some of the technical features, in particular, the discharge pressure, degree of protection, maximum power consumption, efficiency, rotation speed, degree of acoustic pressure. When installing a fan on a Gazelle, you must follow the safety rules - the engine must be connected to the mains correctly.
Fan designs
There are only five design options. Centrifugal, axial, diametrical, diagonal and bladeless designs. Moreover, it should be noted that there are fundamental differences only in bladeless structures. Diametrical and diagonal fans are a kind of centrifugal and axial, respectively. When installing a radiator fan on a car, difficulties may arise - the measures for protecting the devices are not observed. Let's look at the types of fans.
You can select the following types of machines:
- Shared devices.
- Devices of specialdestination.
The first group includes fans that are designed to work with active gas and air flows, whose temperature does not exceed 50 degrees. As for the second group, it uses special equipment. In particular, the elements are all heat-resistant, corrosion-resistant, explosion-proof, which allows the device to be used in hazardous environments.
Mounting Options
There are several options for mounting fans:
- Standard designs mounted on poles.
- Roof fans are placed on the roof of buildings.
- Multi-zone devices are models that are designed to connect to several channels at once.
- Duct fans are installed inside ventilation ducts.
When installing a duct fan, it is important to consider the degree of protection so that large suspended particles do not get into it. For the most part, the drive of ventilation units is an electric motor. There are several options for connecting the motor and impeller:
- Infinitely variable hitch.
- Belt drive.
- Direct connection.
The choice of a specific fan model should be made only after determining the type of device. It is necessary to take into account the area that the device will serve, the installation site, the maximum permissible noise level, the need to protect the device from the ingress of various objects, dust, and room humidity. Separate requirements for devices thatinstalled in cars. It is advisable to install fans that are recommended by the manufacturer.
Classic axial fans
It is also called an axial fan, it is used in the design of household hoods, as well as in complex systems. Such devices can be found in cooling systems for various electronics, in wind tunnels, and in aviation technology. The design of the model is simple, its dimensions are minimal. The design is based on a cylindrical body, an electric drive and a wheel with several blades.
The inner diameter of the cylindrical body must be such that the impeller rotates freely. Between the blades and the housing, the spacing should be on the order of 1.5% of the blade length. In order to reduce hydraulic losses and improve aerodynamic performance, a diffuser, manifolds, and a fairing are added to the design.
Axial fan operation principle
The principle of action is that the blades that rotate, capture air, and then push it along the axis of the impeller. Air flows in the radial direction practically do not move. To adjust the fan performance, it is necessary to set the desired angle between the impeller and the blades. Be sure to take all these points into account when installing an axial fan.
Features of axial fans:
- They do not require a large installation area.
- The device consumes littleelectrical energy.
- Fans are easy to operate and repair.
- Make little noise.
- The cost is not very high.
All these advantages have allowed the axial fan to take root in all spheres of life. They are widely used in everyday life, automotive technology. In order to enhance air exchange, a device with wall panels can be installed in wall openings and other supporting structures. Devices can work in one of two modes - forcing or suction of air.
Centrifugal fan type
The efficiency of this type of fan is very high. With these units, very high pressure can be generated. And operation can be carried out in very difficult conditions. It is hollow, made in the shape of a snail. It has inlet and outlet pipes. In order to provide the desired degree of rigidity, the casing is made with transverse strips or ribs. As a rule, the casing is reinforced by welding.
Noise-absorbing panels are installed in the "snails". This is necessary in order to reduce noise during operation of the installation. The rotor is made of blades, two discs and a hub. The design of the impeller determines the conditions for its use:
- If it is necessary to transport air streams with solid particles, it is best to use discless devices.
- If you need to move air streams with a low content of solid particles, it is recommended to use single disc fans.
- Double discs are suitable for moving air in various pressure ranges without solid particles.
- Three-disk fans can achieve double-sided suction.
Features of the location of the blades
The wheel on the rotor is fixed with hubs. Blades are installed on the disks and hubs. The efficiency of the entire unit, as well as its performance, depends on the shape of the blades:
- If they are curved backwards, this will prevent the accumulation of dust inside the unit. Therefore, these devices can be used in conditions where there are a lot of suspended particles in the air.
- If the blades are curved forward, it means that the fans can operate under high pressure conditions and with large volumes of air. They are very resistant to erosion.
- The centrifugal fans are compact in size, but the efficiency is average. The rotor elements in them are treated with protective compounds.
- The aerodynamic wing can provide maximum quietness as well as reasonably good performance. The appliances are resistant to high temperatures.
How does a centrifugal plant work?
Suction on these fans occurs in the longitudinal direction, in the radial direction the flows collide. Air masses move in a cylindrical housing. You can break the whole process into the following steps:
- The air between the blades tends to the edge of the rotor as the impeller rotates.
- A zone is formed in the center of the wheel, in whichpressure is lower than around. This causes air to be sucked in from outside.
- At the center of the chamber, the air flow changes direction, it moves not in the axial, but in the radial direction. In this case, it enters the zones between the blades. Due to the fact that the impeller rotates quickly, the air rushes to the inner wall of the device.
- In this case, the kinetic energy is converted into compression, the speed of the air decreases. In the cochlea, a volumetric air flow is collected, and excess pressure appears.
- Air tends to the outlet, then goes to the pipeline and the work area.
Such units are used in supply and exhaust systems for garages, large premises, shopping centers. In other words, where it is necessary to carry out continuous powerful ventilation. Radial fans are used exclusively in hazardous industries to remove polluted air as quickly as possible.
Diagonal fans
These are designs that have taken all the best from the centrifugal and axial fan. They have a special shape. The impeller is similar in design to the drum used in the radial design. The blades on the impeller are located strictly parallel to the axis of rotation. Such devices are enclosed in a cylindrical housing, outwardly they are more similar to axial ones, but the principle of operation is different due to the fact that the impeller has design features.
Air starts to move along the axis, after which it changes directionabout 45 degrees. Due to the fact that centrifugal injection occurs, the flow rate increases. And this means that the efficiency of the installation is improved. The efficiency of diagonal fans is about 80%. Among the advantages of such designs, one can single out the fact that they have small dimensions, low noise level, high performance.
Such devices are used in medium and small ventilation systems, in which there is a large length of air ducts. Regardless of the length of the air ducts, the cost of installing a fan will be the same - remove the old one 100-200 rubles, install and connect a new one - 1000-1500 rubles. Depends on the specific company. Replacing a fan on cars will cost 500-1000 rubles, depending on the brand. If necessary, a fan sensor is installed - on cars, this will require draining the liquid, so the cost of the work increases.
Tangential installations
They are also called diametrically. They are made of a long body, on which a nozzle and a diffuser are mounted. The design also has an impeller in the form of a drum with inclined blades. During operation, the air mass moves twice at an angle of 90 degrees to the axis of rotation.
The shroud of this type of fan is about the same as that of radial fans. That's just the air duct is along the side panel. The following device features can be distinguished:
- The flow is as uniform as possible.
- High dynamic performance.
- Can expanddevice to select the flow direction.
- Efficiency from 60 to 70%.
- Works almost silently.
All these features made it possible to use fans in split systems, air conditioners, to create air curtains.
Bladeless fan
Household fans of this type appeared on the market not very long ago. The work is significantly different from those devices that were discussed above in the article. The device works due to the fact that the environment strives to equalize the balance between the pressure inside and outside. No additional fan required.
The design of the device consists of the following elements:
- A round or oval frame that is designed to eject and draw in air.
- A miniature turbine that sits at the base of the fan.
- Elements for fixing the frame.
- Electric motor.
The operation of the fan is as follows:
- As soon as the electric motor turns on, the turbine starts to move.
- Through the perforation in the housing, the turbine draws air.
- Due to turbulence, air is accelerated by about 15 times. It exits through the slots that are located around the entire perimeter of the frame.
- Air currents bend the entire surface of the ring, after which they tend to move in the required direction. Due to the aerodynamic properties of the devices, air is drawn into this flow from the side of the annular frame.
Bladeless fans have the following advantages:
- Maximum smooth adjustment of airflow speed.
- The device is convenient and safe.
- The air direction can be changed by adjusting the position of the ring.
- Compared to axial, bladeless power consumption is about 20% less.
But there are also disadvantages. These include very high noise levels and cost. Installing this type of supply fan will cost a lot.
Domestic fans
Fans that are used in everyday life can be classified according to the place in which they are installed. There are window devices that are mounted in the vents or in the wall near the window. In such devices there is no air duct. Typically, this type of equipment is used in hairdressers, cafes, and other public places.
It is worth noting that it is rather problematic to embed such devices into metal-plastic windows on your own. Window fans can be either square or round profile. On some models, you can find check valves that prevent dust from entering the room.
Kitchen fans allow you to remove any odors and fumes that arise during cooking. The fan is installed in the exhaust hood. There are built-in hoods, flat and domed. There is only one requirement for kitchen fans - they must be heat resistant. Also they shouldexternal safety net present.
By installing fans in the bathroom and bathroom, you can get rid of odors and high humidity. In order to increase the efficiency of exhaust ventilation in the bathroom and toilet, overhead ceiling or wall fans are used. The devices are compact, economical enough, and most importantly - very easy to install. The inner part is placed in the ventilation duct, the outer part is closed with a decorative grille. But it is worth noting that in bathrooms it is best to use fans with a hydraulic sensor.
Vehicle Fans
The article shows installation diagrams for fans for various purposes - supply, automobile. And the difference is only in the connection method. On machines, the cooling fans start automatically. There are two fans in total in cars:
- On the engine cooling radiator.
- In the heating system.
The first fan works automatically, turns on only when the temperature in the engine cooling system rises. In order to monitor the temperature, a special sensor is installed in the radiator.
On more modern vehicles, the fan is controlled by an electronic unit that controls the operation of the entire engine. When installing fans on the Niva, one important rule must be observed - correctly connect it to the on-board network, otherwise failure is possiblewindings.
As for the fan in the heater, it is driven by a switch on the dashboard. On vehicles with air conditioning or climate control, a fan blows over two radiators. One is connected to the cooling system and allows you to warm the air. The second - to the air conditioner and cools the air in the cabin. When installing a cooling fan, the main thing is not to confuse the sides so that the air moves in the correct direction. Fasteners are made using a bolted connection.
