Low-power centrifugal fan gives little use. Even quiet exhaust hoods are equipped with collector engines, very noisy. If the fact does not scare, proceed to the choice of funds. We will show how to make a centrifugal fan with your own hands from the objects at hand. If in a typical - axial - fan the motor and the impeller are important, here, to everything else, the case is added. Let's try to assemble a centrifugal fan by ourselves.
What is the centrifugal fan
Centrifugal fan is used as a duct. To simplify consideration, let's say that a vacuum cleaner contains something like a duct fan. Now think:
- Dust is sucked in with a hose.
- Passes to the bag( tank, compartment).
- Filters out.
- Passing the engine.
- Thrown from the back of the case.
Due to this, it turns out: inside there is a centrifugal fan formed by a drum( squirrel cage), mounted on the motor shaft. This is not enough. The impeller engine is enclosed in an airtight housing, through which the air flows out. Without a dense casing, the meaning of the centrifugal fan operation will be lost. Here is the main difference. Unlike axial fans, often serving for personal needs of a person, centrifugal are used in the economic sphere: room ventilation, cleaning, air cleaning. To understand how to make a centrifugal fan, examine the principle of the device.
The principle of operation of the centrifugal fan
The centrifugal fan operates due to the dynamic characteristics of the flow. Try to tie the stone to the thread and twist around itself in a horizontal plane. The hand feels a noticeable tension, if the connection is broken, the projectile will immediately fly out tangentially to the circular trajectory of rotation. Air molecules also behave in a similar way: on the blades, the wheels acquire significant speed and, being held by nothing, are carried away to the outer perimeter. Then the channel system already gives the flow the right direction. Finally, air enters in the center, usually on the opposite side of the engine.
We observe a picture inside the vacuum cleaner:
- The air from the bag( tank, container), cleared of dust, comes to the engine from the front side and goes into the center of the drum.
- Accelerated by blades to considerable speed, molecules are thrown out. Pass through the channels of the hermetic case, simultaneously cooling the engine, leave the belly of the vacuum cleaner on the back side.
Design feature: the blades of a centrifugal fan create pressure, if the casing is leaking, then the air flow will be disturbed. Therefore, the difficulty for the self-taught master is to create the right conditions.
In good hoods, engines with tangential( centrifugal) type fans are used. In selected design surprising duo squirrel cells. In the latter case, a pair of impellers is mounted on both sides of the engine on the shaft. Then the air enters from two directions perpendicular to the plane of rotation of the wheels. Thus, the efficiency of the centrifugal fan increases.
How to make a centrifugal fan
From the above, an obvious way to accomplish this is to remove the tangential fan from the hood, for example. Advantage: quiet operation is ensured. The manufacturer complies with the standards prescribed by the standards, therefore, the factory-class hoods are relatively quiet. We believe that for most readers this is not the best solution to the problem, we will continue consideration.
Vacuum Cleaner
A ready-made centrifugal fan is concealed inside the vacuum cleaner. A big plus is that there is already a ready housing that needs to be mounted into the channel in place. Additional benefits include:
- Vacuum cleaner motor is aimed at long-term operation. Twists the blade all day long. Winding more often protected from overheating, in addition, the air passes through the channels, cooling the stator.
- The vacuum cleaner's engine is aimed at overcoming significant pneumonloading. With a personal analysis of this assistant housewives will see inside the safety valve. Try to remove and blow the power of the lungs. Does not work? And the engine makes it joking! Clamp the inlet or fold the hose in half. The click, coming from the inside of the case, reports a trigger. We believe that such a force is more than enough to ventilate the object.
- Plus - suction power( in aerowatts) is indicated in the technical specifications, similar to the pressure generated. Thus, it is easy to calculate in advance by the formulas, whether the engine power is sufficient for the chosen task. Sometimes manufacturers are so kind that they indicate the speed of the flow, for example, 3 cubic meters per minute. Any calculate: per hour - 180 cubic meters. Due to the high power, the flow rate will be maintained, despite the twists and turns of the duct.
The lack of a vacuum cleaner engine - noise. In addition, the collector motor sparks, which interferes with the power supply. You will need to make a surge protector in order not to burn imported home equipment. The noise level is high. Exceeds 63 dB, allowed to produce in the apartment according to the law.
Washing machine
What else to assemble a centrifugal fan? The image of a front-loading washing machine came to mind. If the door is removed and the channels are made in the case so that the flow cools the motor windings, the centrifugal fan is obtained. Plus - the working compartment of the washing machine is sealed. Simply remove the tank wall near the engine to get a kind of centrifugal fan. The drum will have to be radically reworked to trap air. The case will need to be disassembled.
The main dilemma arises: whether to dismantle the tank. Most models are specially made so that, without damaging the fasteners, the operation cannot be done. This helps service centers keep track of tricksters who make repairs. In any case, the drum is cut in place to produce in the walls of the blade. Bend the steel inward so that the structure does not touch the tank. Option: from the walls of a steel cylinder, and bend the blades of the desired shape in the image of factory industrial models of centrifugal fans.
The main thing is the correct selection of speed.1000 turns on the spinning is enough. The diameter of the drum is large. The vacuum gives 6000-16000 revolutions per minute, but the radius of the blades is much smaller. Therefore, it is necessary to evaluate the linear velocity. As you know, the circumference is directly proportional to the radius, therefore, if the drum diameter of the Samsung washing machine is 45 cm, it turns out to be at least three times more than the vacuum cleaner - equivalent to a speed of 3000 revolutions per minute( minimum).But! At the same time the wheel area is much larger, therefore, the stream is formed grandiose.
From this we conclude that the speed of 1000 revolutions per minute, all the more so, 1500 revolutions per minute is enough to independently make a centrifugal fan out of a washing machine. The capacity is about the same, but the specific pressure of the flow will decrease. Much depends on the shape of the blades, we strongly recommend to inquire on the forum of physicists and hydraulics. The simplest option is to borrow the blade from the floor fan. Plastic is welded using a set of plastic bags and a soldering iron, which will strengthen the flywheel on the shaft.
The main thing to keep tight. It is recommended to seal off the extra holes that the drum abounds in. A homemade centrifugal fan from a washing machine is dangerous to use( if there are safe tangential fans), it is recommended to close the hatch for loading laundry with a solid grille. For example, make from the front side of the case a row of holes for the installation of the element. The device of the centrifugal fan is complemented by a solid fence. Make a grid of steel bar and fasten the bolts.
Regulation of the engine of the centrifugal fan
In 85% of cases, the engine in the washing machine is collector. Such, by the way, work also from a direct current. The direction of rotation is determined by the voltage polarity.
About the scheme of adjustment of turns. The principle of operation of a centrifugal fan requires the use of spin modes. Find the thyristor circuit that adjusts the cut-off angle and adjust as necessary. For maximum speed, connect the motor to the 220 V network. We consider the questions to be open, what is a centrifugal fan, and how to make it.
