What is Fan: Definition and 346 Discussions

A fan is a powered machine used to create a flow of air. A fan consists of a rotating arrangement of vanes or blades, which act on the air. The rotating assembly of blades and hub is known as an impeller, rotor, or runner. Usually, it is contained within some form of housing, or case. This may direct the airflow, or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors, handcranks, and internal combustion engines.
Mechanically, a fan can be any revolving vane, or vanes used for producing currents of air. Fans produce air flows with high volume and low pressure (although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to an air-fluid stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan.

Typical applications include climate control and personal thermal comfort (e.g., an electric table or floor fan), vehicle engine cooling systems (e.g., in front of a radiator), machinery cooling systems (e.g., inside computers and audio power amplifiers), ventilation, fume extraction, winnowing (e.g., separating chaff of cereal grains), removing dust (e.g. sucking as in a vacuum cleaner), drying (usually in combination with a heat source) and providing draft for a fire.
While fans are often used to cool people, they do not cool air (electric fans may warm it slightly due to the warming of their motors), but work by evaporative cooling of sweat and increased heat convection into the surrounding air, due to the airflow from the fans. Thus, fans may become ineffective at cooling the body if the surrounding air is near body temperature and contains high humidity. A fan blade is generally made of wood, plastic, or metal.
Fans have several applications in the industries. Some fans directly cool the machine and process, and may be indirectly used for cooling in the case of industrial heat exchangers.
These are critical machines and responsible for operating the entire plant, which may shut down without the proper fan. In mine and tunnel, it also used as safety equipment.

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  1. uncleoscy

    Would it be possible to make a self powered fan?

    If you were to have a fan, that has a button, that whenever you press it, the blades rotate (like those mini fans you can find at stores). But, when the blades rotate, they power electricity that powers the fan itself? Kind of like wind turbines but without the wind part.
  2. B

    Misc. Airflow calculations for levitating a foam golf ball

    Im trying to find someone or a company who can do some calculations for me. I started with a fluid dynamics modeling company and they felt I would need a physics calculation. I need to a foam golf ball to be picked up by a column of air and held in place at aprox 10” until it is knocked off the...
  3. C

    Question about motor efficiency and its electrical "power" rating

    i have an oven fan motor and its rated at 15watts, is this output or consuption if its the output whats the efficiency, how many watts is needed to make it run at full capacity thanks i n advance
  4. S

    Would a Centrifugal Fan Be Better for Moving Air Through a Small Hose?

    I have a plastic box and i am trying to move as much air through it as i can. I use a small garden hose to connect the box with some wall mounted fan (see the image attached). Given the small diameter of hose (2cm) and big fan (9.2cm) i am wondering if it would be better to use a smaller fan...
  5. ArnoVonck

    Fan-motor system resonance problem

    Hello everyone, I am a student doing an internship at IMEC, Belgium. I am studying a fan driven by a motor. This fan-motor system goes into resonance at a control frequency of 36.2 Hz. This corresponds to 18.1 Hz impeller frequency. The operating range of this fan is 30 to 40 Hz, so we can't...
  6. phyzguy

    Solve the Mystery: Fan Controller Info Needed

    Does anybody have any info on this fan controller? I don't even know what to Google, because I don't know what that second character is. Any help?
  7. Engineergn

    Snail Fan Motor High Current Issue

    We producing industrial steam boilers. We also produce snail fans for our boilers. The problem is our fan blades are a little bit heavy for our motors until blades get warm. "We can't use more powerfull motors cause of energy saving." We control our fan motors via drivers and our fan blades...
  8. B

    Calculating the speed air comes out of a fan

    Hi, I have a task where i have to calculate the speed of which the air is flowing out of a drones propeller fan. This is all i have been given: The mass of the drone m = 0.42kg, There are four propellers the lenght of each blade d = 0.21m, the air density is 1.3 kg/m3 and g=10 m/s^2y. And the...
  9. D

    I need a small fan to push a lot of air because my bigger fan is too loud

    I remember a quick demonstration in high school of air like pushing more air thru a tube maybe 3-4in dia. than the little airbrush would push by itself? I think. I scaled that up at a weld shop with shop air and a 10in alum pipe that was like 3 feet long. I put a blow gun in the pipe and made a...
  10. S

    I Dust sticking to fan blade downstream of rivet head

    Why does dust stick to the fan blades just downstream of the rivet heads, forming a comet-tail like effect?
  11. R

    Electric fan to get ramjet airborne?

    Does anyone know of prior work on the use of an electric fan to supply input air to a ramjet until the air speed is sufficient (~0.2 M) for normal operation? It's obviously possible, but might not be practical. The objective being the simplicity of a pulse jet without the vibration issues.
  12. G

    Which fan placement offers the most airflow for cooling electronics?

    I have two identical fans to cool electronics within an enclosure. From the two drawings/options, which option offers the most airflow? Thank you.
  13. L

    Best fan placement for optimal air flow

    I'm building a fume extractor for my workbench. I would like to hear your thoughts on the best placement for a fan so I get the maximal suction/airflow. I made a sketch with the general dimensions. The fan could be either in the A position before the filter or in the B position after the...
  14. S

    I Ceiling fan pressure increase or decrease

    Would air pressure increase or decrease due to a ceiling fan in a room?
  15. Anachronist

    B Beam of air: Extending the range of a fan

    If one Googles for "laminar flow nozzle", one finds many interesting tutorials on creating a nozzle for a laminar water jet; a stream of water that remains coherent over a long distance without breaking up. These typically consist of a large-diameter tube with regions inside (like sponges and...
  16. R

    Solving Ceiling Fan Woes | Home Improvement

    There are three ceiling fans in my flat - one in the living room and one in each of the two bedrooms. Two of them make wonderful breezes. The other one, in the main bedroom, seems to cut through the air without disturbing it at all. I've looked closely at them and they all seem to be the same...
  17. T

    Which Is More Efficient: Dyson Fan vs Market Fans

    We all know about various kinds of market available blowers and their efficiency is well known more or less. I recently came to know about dyson fan/air multiplier I want to know which one, whether market available blowers or the Dyson fan is efficient in terms of creating mass flow rate at...
  18. KyleGranger

    Heatsink and Fan Design/Simulation

    I would like to do a simulation comparing the cooling performance of a heatsink with various parameters such as fin length, fin thickness, fin spacing, etc. I have Ansys Icepak available for this simulation. From what I see, I can set the inlet pressure or velocity. The fan gives me CFM so I'm...
  19. B

    Interference pattern of a fan of plane waves

    So I've kind of made the assumption that there will be an odd number of plane waves and the same amount above and below the z-axis. Then, using the diagram below, I determined the angle the nth plane wave makes with respect to the z-axis to be the angle it makes with respect to the n =1 plane...
  20. S

    Solve Lift Fan Problems: 6hp Engine, 5 Blades, 45 Degrees

    Have a 6hp engine turning a 5 bladed fan at 45 degrees. this is my lift fan. The problem is that right side is drawing air in while the left side seem to be blowing air out. The fan is 17" above the ground, and 4" below the deck and parallel to the ground running at 3200rpms. What am I doing...
  21. C

    B Cooling the room with a ceiling fan and skylight window

    Hello, So I know that a ceiling fan either operate clockwise (winter mode) or counter-clockwise (summer mode) and while the fan is meant for just moving air around, I'm wondering if utilizing a ceiling fan and an opened skylight window only a few feet near the ceiling fan would help move the...
  22. P

    Electronics Upgrading Capacitor-Based Fan Regulators for 500-1000 Watts

    A capacitor based fan regulator is rated for maximum 100 watts. What components need to be replaced to make it suitable for 500 watts or 1000 watts...
  23. I

    HVAC Redirecting Airflow with a Curved Surface

    I want to change the direction of airflow from a fan. The fan is covering a window so as to bring fresh air into the workspace, exhausting warmer air through open windows throughout the workspace. It would help cool those in the immediate area of the fan if it were blowing 90 degrees to the...
  24. J

    I Seesaw problem with a man connected to a fan by a rope

    Men is at seesaw , connected with rope to beam which is conected to seesaw with joint,when fan is off ,seesaw is stay at brawn box. When you turn ON fan,man and beam are in balance,can seesaw flip to right side? (If beam is conect with fixed conect to seesaw then for sure it will flip to right...
  25. DaveC426913

    Why Do Some Classic Sci-Fi Stories Fail to Engage Modern Readers?

    I was just browsing the Beloved stories from when you were much younger thread and began thinking about the beloved stories that aren't beloved by me. I could not make it past the first few chapters of Dune, no matter how many times I tried. I literally kept falling asleep. Halfway into...
  26. M

    How can you determine if a fan is better at blowing or sucking?

    I am trying to determine if they are better placed in positions where they suck or blow. Is there a rule to determining this?
  27. I

    Find the Best Fan or Propeller for Efficient Cooling in a 3 1/2" Device

    I have space in a device about 3 1/2" across and need to get 12cfm of fresh air from this area via a reducing funnel with a ration of 15:1, into a 3/4" tube requiring cooling air inside it at a velocity of 4000fpm. How do I select a fan or drone propeller combination that will do this?
  28. Orange_Squash

    Lapsed sci-fi fan, looking for recommendations to get back into it

    As a teenager I ripped through my father's old sci-fi novels - Heinlein, Arthur C Clarke, Asimov, Herbert, Dick amongst others. I'm also a big fan of Douglas Adams but haven't read all of his books yet. I really enjoyed the sci-fi short stories genre, but again stuck mainly to the above...
  29. Andrea Vironda

    Automotive Aerodynamic drag on a car and recovering some of that energy using a fan

    I think that driving at 130-140 km/h a car could dissipate 5-10 kW of energy only because of aerodynamic drag. Why cars don't have a fan somewhere to exploit the aerodynamic drag? For example a Pelton turbine
  30. G

    Convection powered bladeless fan style ventilation?

    I'm still trying to understand the operation of these fans. How does the geometry downstream influence the flow. Specifically, there is an 8" ventilation tube in the ceiling of my warehouse. I'm thinking that I can extend it until it is 3/4 of the way to the floor. If I crack open an overhead...
  31. T

    Position of the fan inside a convergent nozzle

    I want to present two scenarios here. First, there is a convergent nozzle shaped structure having a fan/blower fitted inside. In this case, the fan/blower is fitted at the throat of the nozzle. The inlet to throat ratio isn't important here. And the second scenario, the same nozzle is used but...
  32. H

    Electronics Portable Solar panel system to run a small computer fan

    Hi all. Recently I purchased two portable USB solar panels, which are rated at 5 watts each. They both came with a 'battery bank' consisting of a single battery all running on 5 volts. I also purchased a 5 volt USB computer fan. My question is; can plug all these things in together so that...
  33. DaveC426913

    What DOES the direction of a ceiling fan do?

    Is there a reason? My hypothesis is that running a fan one direction versus the other direction has little direct effect on circulation - the air moves in a toroidal shape - either upward or downward either way - the only real difference is that downward creates a direct draft/breeze, whereas...
  34. V

    Does Fan Speed Remain Constant Under Varying Loads?

    I have a question concerning the electric motor that drives a fan. A fan can experience different loads depending on the pressure build-up in the ducting behind the fan and depending on the air density. Do fans keep their revolutions per minute constant if the pressure build-up or air density is...
  35. F

    B Sailboats providing their own wind

    I happened to be watching this cartoon and this one scene seriously bothered me... This... just feels like it wouldn't be a workable solution. Am I wrong? I can't say I perfectly understand how fans or propellers work, but I would imagine that by pushing air or water in one direction, equal...
  36. HotFurnace

    High CFM Fan Airfoil: Expert Guide

    Hi airfoil experts, I brought two high speed fan for magnetron cooling, and upon destroying one due to my mishandling of the stuff, I found out these fan have surprising nice airfoil. See the pictures and you will understand their construction. The rotor part looks just like a normal air flow...
  37. B

    Function for the Thrust of a Ducted Fan

    I'd like to design a ducted fan capable of generating 800 N of thrust. Though I can do fairly high level math, I just really don't even know where to start in calculating (or at least relatively accurately estimating the thrust generated by a propeller, particularly a ducted one (as I understand...
  38. Edwina Lee

    Running an AC Mains powered fan at different speeds

    My mother has an alternating current extractor fan plugged into the mains. I want to run it at different speeds. I am thinking of using a light dimmer switch to deliver variable voltage to control the fan speed. (An electrical engineer friend told me that it is possible only if the fan is...
  39. J

    Can I Verify the Flow Rate of an Exhaust Fan Based on Specifications?

    I've been given some specifications by a company for an exhaust fan that I am looking at purchasing for my company. They tell me it is 10,900 cfm. Then given some specs on the electrical requirements. I am wondering with the information given could I check their given flow rate? I imagine that...
  40. B

    Fan motor stalling on running winding

    Hi Guys, Single phase capacitor start induction run motor keeps running even after start capacitor is disconnected by centrifugal switch. But in practice, table fan motor stalls and hums when I disconnect starting capacitor when fan motor reaches full speed. Why one phenomenon works in certain...
  41. V

    Use only a powerful fan without a compressor?

    Hello & Thanks, Is it possible to use only a powerful fan without a compressor to make very cold air ? Thanks
  42. T

    Air conditioner fan not starting

    I have a problem with my air conditioner fan not starting. As seen from the schematic below, when I test for voltage between the brown and black wires, I get 0 V (this is the problem). The indoor unit isn't sending the control signal to turn the fan on. The compressor powers on fine though. When...
  43. D

    Electronics Need a small motor and fan to blow air into a 4 inch sphere

    I have a 4 inch sphere with a 22 mm opening. Inside this sphere I will have 3 styrofoam balls 20mm diameter each and 3 styrofoam balls about 5 mm each. I need a wind source to blow wind into the ball through a tube approximately the diameter of a drinking straw, the wind being strong enough to...
  44. N

    Distance between a box fan and a perforated plate

    I have a question about the relationship between fan CFM vs the distance it is installed away from a perforated wall. I did a simulation and it shows that keeping a distance between the two will make the fans have more CFM, less static pressure than the fans directly installed on the plate. If...
  45. F

    Can a defective fan motor cause a run capacitor to go bad?

    I already have made the thread "Can a defective DRC [Dual Run Capacitor] on a heat pump cause the fan motor to go bad?" Earlier today I told my father how a defective DRC on my heat pump caused the run winding on my fan motor to burn up. My father asked me if a defective fan motor can cause a...
  46. F

    Can a defective DRC on a heat pump cause the fan motor to go bad?

    I noticed that the outdoor fan on my residential, split-system heat pump stopped working in mid-October. I don't know for sure exactly when my outdoor fan on my heat pump stopped working. It might be that my outdoor fan did not work for months before I noticed that the outdoor fan did not work...
  47. F

    Why does the outdoor fan on a heat pump need to run on heat mode?

    The outdoor fan on heat pumps always runs when the compressor is pumping refrigerant when the heat pump is in heating mode unless the heat pump has defect(s). I don't understand why the outdoor fan on a split system heat pump needs to run when the heat pump is in heating mode. When a split...
  48. M

    Motor fan pulley sizing for HVAC

    Hi Everyone! I designed a motor fan system pulley system. So, basically, the motor is of 15 kw with a driver pulley of 7" dia. And through a v-belt I attached a backward curved fan with a 10" dia pulley on the shaft. My fan shaft power is 13.24 kw. This selection was given to me by the software...
  49. A

    Calculating the velocity and pressure profiles across an axial fan

    Hi, This is my first post on the PhysicsFormus I am trying to design an inlet and outlet for an axial fan and calculate velocity and pressure profiles in the duct. See the sketch attached. The ultimate goal is to carry out a CFD study but I was wondering if there is an analytical solution for...