What is Air flow: Definition and 153 Discussions

Airflow, or air flow, is the movement of air. The primary cause of airflow is the existence of air. Air behaves in a fluid manner, meaning particles naturally flow from areas of higher pressure to those where the pressure is lower. Atmospheric air pressure is directly related to altitude, temperature, and composition.In engineering, Airflow or air flow is a measurement of the amount of air per unit of time that flows through a particular device.
The flow of air can be induced through mechanical means (such as by operating an electric or manual fan) or can take place passively, as a function of pressure differentials present in the environment.

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  1. R

    Air flow differance.Square versus round tubing

    Hello.I am trying to make a snorkel for my 4x4 truck.I would like to use 2 1/2 inch square tubing but all snorkel manufactures use round.My dad says round flows more air.I believe round must be better.But I want to no why?I now I can get more mass or volume per square inch in a square tube at 2...
  2. A

    Pressure in the lungs and air flow

    I've been really confused about inflation of the lungs and airflow. Given a lung compliance of 0.25 L/mmHg, this means that 2 mmHg is required to inflate the lungs by 500mL. Does this mean that the pressure difference between intrapleural space and the alveoli must be 2 mmHg more than what it...
  3. J

    Can Air Compressor Noise be Cancelled Without Affecting Air Flow?

    Is it possible to cancel noise from an air compressor while still allowing air flow to keep it cool?
  4. C

    Exhaust air flow parameters for car engines (otto & diesel cycles)?

    Does anyone know any sources (i.e. car manufacturers) that provide the exhaust air flow parameters for the some specific car engines? I need stats on various otto & diesel cycle engines (small compact car engines, large semi truck engines, etc.). When I say exhaust air flow parameters, I need to...
  5. M

    Air Flow Formula Help: Calculating % of Volume Lost in 2.8 Seconds

    Hello New to the forum and have a fairly simple problem. I am looking for help in building an equation for volume lost in a container. Example. Known variables: Container has a volume of 44 fl oz Container will be pressurized to 6" of water column. Container has an orifice with...
  6. Pengwuino

    Screen doors/windows disrupting air flow

    Where I live, temperatures fluctuate like crazy (I technically live in a desert climate) . We can have 80F degree days and have it drop to 40F degrees that night. My house, for whatever reason, will have the upstairs heat up to the 80 degrees, yet when it gets cooler, it will take a long long...
  7. B

    Air flow through increasing pipe size

    Air flow in shop is through 1/4" hose. pneumatic motor has 1/2" inlet plus the tubeing to and from valve is also all 1/2" tube. what would be a general equation to model the pressure loss or increase to the motor. Shop air: 80psi 60cfm
  8. G

    Air flow in Convergent divergent nozzle

    i understood the air flow properties variation in convergent divergent / condi nozzle or laval nozzle for subsonic flow based on the formula, for a incompressible flow : density * Area * velocity = constant as the total pressure in the flow is constant dynamic pressure is...
  9. H

    Placing air suction next to the air flow ventilation of a PC. Good or bad idea?

    This is something that came up at work, as there are four computers running with their air vents placed four to six inches away from the air suction (so that it would suck up the air which was blown out from the air vent fan of a PC.) While this may seem like a good idea on paper (as the suction...
  10. I

    Air flow rate in a closed pipe

    I can't seem to find an equation that fits the situation I am facing. Either that, or I just don't believe the answer the current equations are providing. I am trying to develop the size for an air compressor to fill up a train braking sytem. I have equations for most of the system, but I...
  11. W

    Calculating Thermal Energy of Hot Air Flow

    haw can i calculate the thermal energy (watt or BTU ) of the hot air (or the exhaust air of the chimney) according to the following : Temp. : 250 C hot air flow rate : 11 000 m3/h thanks
  12. D

    Air flow in relation to water depth

    I am building a home aquaculture system using air lift pumps. I have formulas for calculating water flow and for metering my cfm with orfices. My question is how does water depth effect air flow. I know that 1 psi = 27.68 inches of water. So my question is do I need to increase my psi...
  13. M

    Fluid mechanics, why does the air flow faster over the wing?

    Why does the air flow faster over the wing? In my fluid mechanics course we used streamlines and a half body to show that the air flow faster over a half circle, but I do not understand why it does so.
  14. F

    Calculating Air Flow Within a Pipe

    Consider a pipe. One end of it (hole) is malleable, in that we can make it larger so that the cylinder adopts a conical shape (yet the other 'hole' does not change). If one were to apply suction at one end of the pipe, with respect to air flow, how does the pressure gradient vary within the...
  15. e2m2a

    Effect of air flow on temperature inside box

    If I have a heat source on for a one hour period inside an adiabatically sealed box, such as a 10,000 watt light bulb turned on for an hour, and simultaneously I have a fan on that constantly circulates the air inside the box, would a temperature probe measure a lower temperature due to the...
  16. S

    Engineering Motor control design for air flow valve

    Homework Statement build a circuit that open and closes the valve using, electronic components Homework Equations none known yet The Attempt at a Solution this is my first try
  17. S

    Dust Collection Foot Air Flow Help

    Please move to the right place if I have posted in the wrong location. I want to improve the performance of my dust collection foot on my CNC machine. I am using a dust collector that has a 2 HP, 120 volt, 60 Hz, 20 amp peak, single-phase motor. It generates 1550 CFM air suction capacity...
  18. C

    Calculate Air Flow in SS SCH40 1" Pipe | 80 psi at Discharge

    The following is the only information that is given at this point in time: Air flow through SS SCH40 1" pipe (ID 1.048"). Pressure required is 80 psi at the discharge point. Assume supply pressure is 100 psi and unlimited in quantity at a constant pressure, supplied from a tank. The pipe...
  19. S

    How Can Air Velocity Be Calculated at a Nozzle's End Over Time?

    Hi, This is not homework, it's for myself. I'm trying to understand it for me only. I have a piston that is translating in a cylinder and pushing/sucking air through a nozzle. It's much comparable to a bicycle pump. The piston is moving with non-linear (exponential) velocity until it slams...
  20. R

    Creating an Air Flow Meter Using an Iron Heating Element

    Homework Statement i am trying to make an air flow meter using an heating element which i got from an iron..basically i have thought of inserting the element into a duct through which i will pass air using a blower,to connect the element with a 12v supply in series with a ammeter...thn i...
  21. T

    Air flow changes in a pipe with the change in gas temp?

    nuclear reactor question air and non condensible gasses being removed from the condenser and processed through a treatment skid through a pipe. steady state value flow rate at 77 deg f is 30 scfm fixed the refer vault and now the temp is 15 deg for the gas. what will be the flow rate...
  22. T

    Air flow caused by fans (game simulation)

    Hi, I'm currently taking a C++ course where we are going to make a project, we are 6 people in our group. We have decided to make a kind of puzzle game, where the goal is to move an object (maybe a ball?) through a room, avoiding obstacles and eventually reaching a goal somewhere in the room...
  23. 5

    Air flow in pipe, diameter change, affect performance?

    I am attempting to build an intake setup for an engine I'm working on. I currently have a 3" diameter aluminum pipe on the throttle body that just curves off to the side. I would like to try and get some cooler air by routing it down into the bumper. I have access to 2.5" diameter piping. I was...
  24. Q

    Need formula/help with mass air flow

    Hello, My name is Quinton and I am doing a small project that includes a small compressed air tank attached to a section of 2" PVC pipe. My problem is I need to find the force that the air creates when all the air from the tank is released through a valve (also 2"). Any help is appreciated...
  25. K

    Pressure Drop Across Radiator And Air Flow

    Hello all, I have some performance data on a particular radiator, and I want to model the system and see if I can't get a simple analytical model to match the data. The problem I'm having is with the air flow rate through the radiator. The only relevant data made available to me is the...
  26. C

    How Does Air Flow Over an Aircraft Wing?

    So I know that the faster the fluid moves the lower the pressure . But what I don’t get about an airplane wing producing lift , so the plane is cutting through the air , and the air molecules are still . Why does the air molecule on the top part magically just speed up ?.
  27. S

    Max possible air flow through a tube

    Homework Statement I had a discussion with some of my friends about this matter, but my physics basics related to fluid flow dynamics aren't well enough to draw a conclusion, so here it is: On the left side of the diagram is a space with infinite amount of air (breathable Earth air) at...
  28. S

    Why Does Airflow Decrease When Blowing Directly Into a Pipe?

    if you use your mouth to blow air through a pipe (an A4 page rolled into a pipe for simplicity) with your mouth against the pipe, the outlet flow is much less compared to when you blow through the pipe with your mouth away from it. In terms of fluid mechanics, why does this happen?
  29. Q_Goest

    Space Shuttle Reentry: Laminar to Turbulent Air Flow

    I would have never guessed that during reentry, and at very high mach number, the flow of air over the Shuttle’s wing is laminar! To make it even stranger, as velocity decreases, there is a transition to turbulent flow across the wing (I suspect this is also caused by an increase in air density...
  30. K

    Pulsating Air Flow Equipment Selection

    Hi all, I was looking for a way to oscillate airflow at a particular frequency as fed from an electrical input. All I'm really looking for is a simple knife gate valve that opens and closes from a saw tooth (rectangular wave) input from an oscilloscope. I was thinking a Solenoid valve...
  31. 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...
  32. W

    Which Fan Design Maximizes CFM Through a 6 Hole?

    Hello I was wondering if there was someone on this forum who could help me with this. Basically my question sums up to this: There are 2 fans with equal size/power/cfm. Air must exit a 6" hole. Which design would produce the best CFM (Cubic Feet per Minute) of air flow? I have attached a...
  33. NightSwimmer

    Question regarding air flow in a closed circuit

    I am new to this forum. I am an applications engineer. I design, build and program industrial automated control systems. I am currently working on a project for a lime calcining kiln. Our project involves an upgrade of the coal-fired kiln's fuel delivery system. This involves a coal grinding...
  34. C

    Making a stronger air flow using 2 fans

    I want to know what setup is best to create a stronger or faster air flow. I want to place 2 fans side by side you have a second fan on front of another. because I already tried running both fans at the same speed the result is the air flow or air current is not strong somehow there's a conflict...
  35. N

    Calculating the Wind Speed Needed for a Weightless Building on Titan

    I think this is a pretty simple question but I can't seem to figure it out: If there is a 90,000 kg building (20 m deep, 10 m long, and 10 m wide) on the surface of Saturns moon, Titan, how fast does wind have to blow over the top to have the structure become "weightless" (the air below the...
  36. D

    Air flow - roof and attic ventilation

    Hi all, I need to know if I'm on the right track with my thinking. I've drawn a diagram that hopefully is not too simplistic and shows what I am getting at. One of these links should work. http://www.roofersreview.com/d/9390-2/Hip+roof+diagram+calc_+copy.jpg...
  37. K

    Air flow through a 90 degree bend

    Hi, Firstly i don't really know anything about fluid dynamics so go easy on me :shy: In simple terms how does air flow through a 90 degree bend? ie where is it moving faster? I initially thought it would be along the outside wall as it has further to travel. If it makes and odds it's an...
  38. M

    Compressible air flow thorugh pipe

    Hi guys: I am wondering with issue regarding high speed (subsonic) compressible air flow thorugh a pipe exit to atmosphere. So here is detail: Air coming from a reservoir and flowing thorugh an adiabatic constant area pipe and exit to atmosphere at the end of the pipe. Due to high...
  39. H

    Calculating Air Flow and Pressure for a Hovercraft

    Hi everyone I have a few questions. First, I am making a small hovercraft and have a fan for a source of air. How can i calculate how much air it moves?? Second, how can i calculate how much air pressure it is putting inside the hovercraft bag for the craft to lift?? Thanks for any...
  40. N

    How to Calculate Air Flow Rate for a Cylindrical Vessel with Perimeter Holes?

    We are having trouble calculating a required ft^3 per minute air flow for a particular vessel which was constructed to measure the accuracy of a vacuum machine. Our vessel is a steel cylindrical drum 1mm thick with a diameter of 22.5" and a height of 34.5". It has 50 holes around the...
  41. A

    Determining Height of Mercury in U-tube: Air Flow Rate of 1200 cm^3/s

    Ok, Air flows through this tube at a rate of 1200 cm^3/s. Assume that air is an ideal fluid. What is the height h of mercury in the right side of the U-tube? Here's a picture: http://session.masteringphysics.com/problemAsset/1001181/6/knight_Figure_15_64.jpg First, I found the velocity of...
  42. S

    Calculating Air Flow Through a Hole

    Hello, I am trying to find a formula for calculating air flow through a hole. If I have a container with a known volume and a pump that can maintain a specific vacuum in the container, is there a way to calculate the amount air that would flow through a leak of a known size? Thanks Solar1
  43. W

    Prsssure vs. air flow baseline

    I am working on an air flow vs pressure chart for a variety of valve components for work and I am hoping someone may know where I could get some comparative baseline data. My setup is a 4' long, 2" diameter PVC pipe with one end connected to a large air compressor tank with a ball valve for...
  44. D

    Linear vs. non-linear air flow

    Lets us a potato gun for an example. Having a source tank filled with air, and when a trigger is activated, the air is dumped straight threw the valve and out the tube. --> --> --> --> What would happen if the flow of air had to go out of the pressurized source (~160 psi ~40 cu. in...
  45. B

    Calculate Air Flow Force for Piping System Setup

    See attachment for piping system setup. Question: How much FORCE will the block feel from the air flowing through the two holes in the lower pipe? I have no idea how to calculate this. Does Bernoulli's equation apply anywhere here?
  46. J

    Air Flow Observation: Wind Instruments

    I would like a way to be able to observe the air flow through wind instruments. I was thinking a lab where the do tests on the aerodynamics of cars. any other ideas. also does anyone know of a facility in the New York area that might be capable of such a technique. I would like to video...
  47. 2

    Air Flow Through Dual Spouts on Laid Down Jug

    If you have a five gallon jug of water with a 1/2 inch spout, and it is laid on its side, because there is no other opening in the jug it empties as air spills into the spout and replaces the water, but if the jug would have another 1/2 inch spout on it, now on top of the laid down jug, Would...
  48. vincentm

    How to Improve Air Flow in Your PC

    Another guide i decided to post here made by moi :) Your PC case should consist of at least 3 fans( 1 intake, 2 out take) we are going to use my PC as a reference. (pics are crappy so bare with me.) your front of your case should posses the intake fan this will suck in air to be properly...
  49. A

    Air flow between two different pressures

    I have a problem for a project I'm doing: I have one chamber that is 120 mm Hg higher than another chamber(which is at atmospheric pressure) and is slowly being deflated. Force being applied causes this 120 pressure difference, and is constantly being applied. The 2nd chamber will always be...
  50. I

    Determine Force/pressure from air flow?

    I'm trying to determine the force or pressure applied to a surface based on mass air flow. I have a 4" pipe, that could also be 3" or 3.5", but for this example we'll stick with 4" OD. .065 wall thickness This pipe has air traveling through it at various speeds, pressures and...
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