Fan Definition and 347 Threads

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. A

    Analysis of Hubbed Axial Flow Fan

    Hey everybody, I am about to make some simplistic fan analysis for a hubbed axial flow fan (Single stage). What makes me confused is if I should use the classical "one stage" approach for compressor design or if there is another way to do this?! My aim is to carry out a simplistic analysis of...
  2. J

    Design of Fan for Turbofan engine

    I currently doing by final project about designing fan for turbofan engine.After discussing with my lecturer,I decided to do it based on axial compressor preliminary design method in Gas Turbine Theory : G. F. C. Rogers, H. I. H. Saravanamuttoo, Henry Cohen book.Now after following the design...
  3. V

    What fan can I use in a close loop application with a backpressure

    I have a test application that required a high velocity (subsonic) air trough a restriction in a close loop system. I would like to know which circulating fan would be suitable (axial, centrifugal, mixed flow, turbo) since the fan will have a backpressure from the close loop arrangement...
  4. F

    What do I need for a solar powered extractor fan?

    Hi there, I'm renting, so can't add power sockets and wires to my flat. My bathroom is windowless and passively vented. I'm going to put a solar panel on the roof and drop a wire down the chimney. I was thinking about getting a 7.5v 2.5w solar panel and a fan and directly connect them -...
  5. J

    Project: Ducted Fans - Feasibility & Suggestions

    I am working on a project that requires 4 ducted fans, each producing approximately 40 N of thrust for approximately 10 minutes using battery power. Is this feasible? Any suggestions about which fan and battery I should use if it is feasible? Thanks
  6. J

    Fan and Filter Seperation Dist.?

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  7. JaredJames

    Why Is My 2kW Fan Heater Only Using 0.7kW?

    Hi, I have a fan heater which is rated at 2kW but when we check what it is actually using (voltage x current) it is only using 0.7kW. I am curious as to why this is? This is the fan: http://www.amazon.com/dp/B000306BL4/?tag=pfamazon01-20 Are these fans 100% efficient? Thanks...
  8. D

    Calculating Fan CFM Needed to Blow a Ping Pong Ball Vertically

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  9. T

    Centripetal force on an industrial fan

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  10. L

    Connecting solar panels to a battery-operated mini fan

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  11. E

    What Happens If You Block a Fan with a Drag Tube?

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  12. L

    My laptops fan is making a loud noise?

    does anyone know how i can fix this? it's really annoying and i don't want to have to bring it in seeing as it sounds like the big external fan
  13. S

    Is Fan Death a Real Threat or Just a Myth?

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  14. N

    Calculating Fan Power & Efficiency: What Data do I Need?

    Hi, How do I calculate the fan power (kW) and efficiency, given the flow rate, static/total pressure across the fan surface? Do I need more data? Thnx in advance.
  15. F

    Computer seems to turn fan on fast.

    Hi everyone, My computer fan keeps turning on fast, and then turning off (I think it's the fan, I'm not sure). The computer didn't seem to do that before. I was wondering if this is a bad sign (overheating?), and what should I check? Ed.
  16. N

    Designing a Fan to Overcome 40N of Force

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  17. K

    Radiators and Fan Arrangement Questions to improve performance

    Hi guys, great forum you have here... basically, a couple of years ago, I've gotten involved in the hobby of watercooling computers by adding a radiator, pump and waterblocks on the cpus and other heat sources. well, as I've been researching builds by other folks, i notice that some...
  18. S

    Need slow flow high pressure wind generator fan design

    Hi, I have been toying with the idea of producing electricity from the cross winds that build up in my house. Basically when I leave a window open one one side of my flat and open a window on the other the wind blows through the house very strong. I want to place a wind generator on one...
  19. S

    Solving Two Bugs on a Fan Homework Problem

    Here's a problem my professor assigned and expects us to know, yet he hasn't covered any of this material. We just started talking about angular velocity, acceleartion, etc. I understand that we are supposed to gather the relationships between these things by looking at the equations, but I...
  20. C

    Energy of Fan Blade: Calculating Speed and Strength

    Thanks to all who posted. The fan was built by Universal Hovercraft it's purpose built for a small hovercraft designed for kids to ride on. The fan is driven by a 5hp petrol motor which has a top rpm of 3000 rpm. I doubt the engine will get to this rpm with the fan attached but at 3000rpm the...
  21. M

    Angular Speed of Electric Fan: Calculations & Results

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  22. B

    Can a 95 CFM Fan Generate Enough Force to Move a 150 lb Object?

    I'm trying to see how fast a fan that produces "x" cfm can move an object that weighs 150 lbs with a cof of 0.04. How would I set up an equation to find this? Thanks
  23. C

    Fan attached to a sled blowing at the sail

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  24. K

    My DIY Squirrel Cage Fan Fume Hood Project

    I just bought this squirrel cage fan off ebay. My idea is to use it for a fume hood. According to seller it runs very well; I will clean, oil, and throw a coat of a paint on it. Got it for 20 bucks. The motor is completely separated from the cage as I wanted. However, it gives no CMF? It is a...
  25. kach22i

    Interrupted air flow at fan inlet, resulting in fan stall

    I'm looking for an on-line paper/article/pdf about ducted fans; "Interrupted air flow at fan inlet (subsonic), resulting in fan stall" which I can print out and read. Centrifugal, axial and or mixed-flow fans included. I have not had much luck doing a Google search on my own, perhaps I'm...
  26. S

    Moment of Inertia of a windmill or fan

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  27. V

    Calculating Torque for Fan Speed

    Hello, I need figure out the torque is required to spin a fan blade at a certain speed. I know it doesn't particularly matter how big the fan is, but how heavy it is. I know a 1gm fan is much easier to turn than a 2gm fan. Can anyone help me?
  28. T

    Calculate the % fan shaft is out of balance

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  29. V

    Will Electric Jet Ducted Fan Planes Be a Reality in Our Lifetime?

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  30. T

    Calculate the % fan shaft is out of balance

    Homework Statement A fan loses an 11 gram piece 460mm from the shaft center. It rotates at 1000 RPM and cannot operate if the shaft is out of balance by more than 8%. Prove whether or not the fan can still operate. Homework Equations Fc = mwr2 The Attempt at a Solution I have...
  31. F

    If you put a fan in front of airplane wings, how powerful would it need to be?

    I was just wondering, that if you attached a fan in the front of an airplane wing, would it fly? If so, then how powerful would the fan need to be for a small model airplane, say 0.4m and 1kg, to fly/hover? Or if i made wearable wings, and i put them on, how powerful then would the fan have to...
  32. D

    Vacuum cleaner with pc fan possible?

    Hi! I would like to ask for some help regarding a project I am thinking of making. Well, the thing is, I would like to make a vacuum cleaner with just a couple of tupperware "boxes" 8sorry, I don't know how you english people refer them to...:P), some tape to prevent air leak and a 63 CFM pc...
  33. H

    What's the purpose of thrust balance in Turbo Fan Engine?

    What's the purpose of "thrust balance" in Turbo Fan Engine? I'd like to know about the purpose of the Thrust balance system in commercial Turbo Fan Engine. Can you tell me the major role of thrust balance system? Also, the relations between thrust balance system and compressor / main bearing...
  34. A

    Air pressure from a ceiling fan.

    I think a ceiling fan would increase air pressure in a room, whilst an exhaust fan would decrease pressure if it was withdrawing air from the room. However with an exhaust fan, If the room was sealed off, wouldn't air tend to flow inwards through the exhaust fan as well in an attempt to equalize...
  35. C

    How Many Revolutions Does a Slowing Ceiling Fan Make?

    A ceiling fan is rotating 1.0 rev/s. when turned off, it slows uniformly to a stop in 2.4 min. How many revolutions does the fan make in this time? Using the result from the above question, find the number of revolutions the fan must make for its speed to decrease from 1.0 rev/s to 0.50...
  36. K

    Isolated phase buswork fan motor

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  37. D

    Design Process of a heat exchanger(evaporator) and fan

    Hello, I need help with my fourth-year design project. The part that I need particular help with is how to design an evaporator and how to size the fan that will create the forced convection over the fins. What are the main things to consider in terms of design steps? What are some good...
  38. C

    Troubleshooting Broken AC Motor House Fan: Tips and Tricks

    Hi, my brother asked me to troubleshoot his electrical house fan. He tripped over it and then stepped on the fan blade which then caused one of the fan blade rivets to break off. A closer inspection revealed that the rivet did break off, however, the bracket that is attached to the electrical...
  39. S

    Need wiring help for mini solar panel to fan

    Hello, I was wondering if anyone could help me wire up a solar panel to a 12v fan. At first i thought it would work if you were to hook up the solar panel straight to the fan but it didn't. I'm not much of an EE, but i ask for anyone's help and understanding. What i have is...
  40. N

    Mirrors would fog up if i didnt turn the fan on

    Hi guys, Recently i had noticed that when i left the hot water in the shower on for a while, the mirrors would fog up if i didnt turn the fan on, so what I am wondering is how is it that the fan can prevent the windows from fogging up, I am assuming the windows fog up because of water vapor...
  41. M

    Cooling a room with A/C (w or w/o a fan)

    Hi, I was lying in bed unable to get back to sleep and I was thinking about something, remembered this forum, and thought I'd post it up here. Hopefully this topic is suitable for this forum. I installed a ceiling fan in my bedroom yesterday. Its a nice 44in Hunter fan and I'm pretty happy...
  42. T

    Electric Ceiling Fan: 0.0988 Rev in 0.208s

    Homework Statement An electric ceiling fan is rotating about a fixed axis with an initial angular velocity of 0.290 rev/s. The angular acceleration is 0.888 rev/s^2. Its blades form a circle of diameter 0.740 m. Through how many revolutions has the blade turned in the time interval 0.208 s...
  43. M

    What type of solar panel is needed to power a 6A desk fan?

    Hi Eureka I'd like to make a solar powered fan, but don't know how to convert the power from a solar panel to the fan. Perhaps I don't have to do anything, I can just hook it up? Requirement: If the sun is out the fan should be running. At night time the fan should not run. In other...
  44. L

    Not such a big fan of chemistry, what about ChemE?

    I am graduating soon with a BA in chemistry and after 4 years I decided it's not a subject I particularly like. I don't want to do any more bench chemistry (working with liquids and beakers and pipettes and titrations). I am thinking about chemical engineering though and I was wondering...
  45. russ_watters

    Is a 12 watt solar panel enough to power a garage ventilation fan?

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  46. K

    KrisDucted Fan Thrust: Understanding Jet and RC Engines

    :confused:Hi all, I’m new here; my name is Kris aged 53 in Norfolk, UK. I’ve been in engineering design all my life so they few theories and ideas I may submit for comment do have some sound basis. Anyway, today lesson (for you to teach me) concerns Jet Thrust and ducted fan motors. I...
  47. F

    Which Power Transmission Option is Best for Connecting a Motor to a Fan?

    I have to design a power transmission from a motor to a fan. There are no restrictions on what I design. I'm not sure whether I should use a direct (flexible) coupling, a universal joint, or a belt drive. I have designed a belt drive before, and from looking at catalogues, it looks like it's...
  48. M

    Notebook computer with loud fan

    I have a notebook computer, Averatec model number 6240, that is loud like a lawnmower. The fan has already been replaced three times (at no cost to me, under the store's maintenance agreement) and now it's doing it for the fourth time! Only a few months after the last repair, it's doing it...
  49. M

    How can the moment of inertia of a single inlet centrifugal fan be calculated?

    Hi, i need to know how to calculate the moment of inertia of a centrifugal fan. I searched the forum but didint find any formula... So please people help me
  50. S

    Noob - Help Power for a DC Fan question

    Hey guys. I am trying to put a fan into a helmet. I have a 3.7VDC, 650mAh lithium ion rechargable battery. I have sourced and found a great battery! The afore mentioned battery is the constant. Now I am having problems finding a DC Fan that will work with my battery. So far I have found only 5V...
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