What is Air flow: Definition and 152 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. M

    Designing an Air Float Conveyor: Calculating Pressure and Flow for Moving Objects

    [Mentor Note: Thread created by moving some posts from a previous thread into this new one by the OP.] if I have 1)10X10 cm box 2) weight 300g 3) The dimensions of the surface sheet that will be in contact is 60x25 cm 4) should be flat with holes for the air 5) that surface either can be an...
  2. S

    Air Friction energy loss on a trampoline

    Consider a 5 m diamter trampoline. It has an area of not quite 20 m2 If a jumper sinks 1 meter into the mat at center, the volume of the displacement cone is 6.5 m3 (1/3 base of cone times height) Because air as to move in over the top, as well as get out from under, the air moved per jump...
  3. T

    B Understanding air flow and resistance

    In a recent thread, I thought I understood what was going on but alas, I am still confused. So I offer this diagram and ask for more help please. Shown is an aircraft holding pattern. The one on the left is flown in still air. The one on the right is flown with a wind coming from the...
  4. Cringle

    Downdraft table -blocking off part of table surface to increase flow?

    Hello everyone. First post! I am struggling to understand an issue in our (histology) lab. We use large downdraft tables which extract the noxious substances we use, mainly formaldehyde, while we process surgical samples. These tables have a steel cover with lots of holes about 5mm diameter...
  5. Y

    Heat circle -- Calculating the air flow needed across a condenser

    Hi! I need to calculate what air flow needs to flow across the condenser so that the heat emitted from the condenser is directed to the air. dT=10÷15 [C] COP =~3 According to the manufacturer's data the fan airflow is 0.67 [m^3/sec] and i need to check if i can use it. thanks
  6. 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.
  7. 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...
  8. 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...
  9. Specialblend21

    Improving Air Flow on a 50ft Houseboat in the Desert SW

    Ideas on moving hot air from houseboat to enhance natural flow with additional solar 12v fans. 50 foot pontoon houseboat mobile home style cabin in desert southwest. Boat has windows but takes hours to cool down in evening when outside temp is cooler. working to isolate why cabin stores so much...
  10. K

    I Graduation of air flow inside a vacuum chamber

    Hi there. I would like to start saying that I am not an engineer or scientist, and that my knowledge about vacuum and vacuum systems, in general, is limited, and I would like to apologize in advance if I am not describing the problem accurately. The application I am posing this question about...
  11. M

    Calculating air flow through a tube

    This is for a campervan project I am working on, I am trying to take outside air that is cold (Canadian winter) and mix it into the return air in my diesel heater. I need to hit a specific minimal CFM to maintain proper Co2 levels inside and I would like to be able to calculate this. The axial...
  12. M

    Optimizing Air Flow for CO2 and Heat Loss in Vans

    My goal is to determine the ideal amount of air flow, in order to keep CO2 below 1000ppm and to minimize heat loss. I calculated the following based off a similar post in this forum, and I am hoping this can be verified so I know that i am in the right ballpark and going in the right direction...
  13. Annindita94

    I Cooling Time for Air Conditioning

    Please advise for cooling time on air conditioning. I have a project and customer asked me to make a comparison between their requirement and my proposal. And here's the result. Let's say that we provide a room with same capacity as above, function, delta T, load on that room, but ONLY air...
  14. Heathbar

    Aerodynamics -- Warehouse fans blowing toward each other

    Hello, all. I work in a warehouse, and in an elevated work area. It's warmer up there because heat rises, but we have a few fans meant to help cool us. Unfortunately, one out of three fans is facing toward another, and I've been trying to explain to my coworkers that if one fan faces another...
  15. F

    Propeller thrust with backwards air flow

    The Blackbird wind powered car travels directly downwind faster than the wind speed powering it. Typically a 10 mph wind from directly behind it will cause it to travel at about 30mph. I am trying to analyse how the car accelerates from rest. I know how it travels faster than the wind speed so...
  16. H

    What is the Differential Equation for Airflow in a Balloon?

    I have a problem. The task is to develop an differential equation of the airflow of a balloon. I know that it is dependent on the volume and pressure. But I can't get a good differential equasion. Can someone help me? [Thread moved from the technical forums, so no Homework Help Template is shown]
  17. M

    Venturi Ejector Air Flow Mechanics

    Hi, I am trying to figure out the strength of the various type of airflow for my Venturi ejector device. Please refer to my diagram that illustrates scenario A or scenario B. The SAME amount of compressed air is injected for both scenario A and B. For simplicity, I have added to an electrical...
  18. Gurleen

    Misc. Air flow splitting in two directions

    Basically the air pump on the left turns on and when it does, the balloon on the right fills up but the other does not. I also tried putting the pump upright but the left one just doesn’t seem to fill? Any ideas of why? There’s no air leak or blockage or anything
  19. X

    Measure flow rate with a manometer (pressure gauge)

    Hello! I have a volume of 50 liters which I pressurize with air so that I read 1 bar on the manometer. But there is a leakage in the volume so after 30 sec the manometer shows 0,5 bar. What is then the air flow ( liter / min) of the leakage?
  20. G

    HVAC How to calculate pressure loss across a perforated and corrugated plate?

    The plate is in inclined position in a chamber where the air flows from bottom to top.
  21. M

    Volume of air flow through an orifice at speed

    Trying to figure out how much air can (or would) flow through an air intake on a vehicle. I have a rectangular intake opening that is 13.52 square inches, the vehicle is traveling at 60 MPH for 1 hour. Obviously more air is being forced into the intake due to the speed but I can't sort out...
  22. G

    Air flow through a hole in a submerged pressure tank

    Hello! I will try to formulate myself as clearly as possible, but english isn't my main language. I'm having trouble solving this problem that should be relatively easy to solve. Let's say we have a submerged pressure tank, constantly fed with air through a compressor, so it's maintained at a...
  23. J

    Automotive Can the mass flow rate change?

    Hello everyone, Can the mass flow rate of air by a propeller connected to an engine through a small tube change if the rpm of the propeller is increased?
  24. G

    I Can i create an air flow through a geometry?

    Is there a way to create/force air flow without using electronic components?
  25. J

    Air Turbine Design -- advice regarding a Hall sensor type air flow meter

    Hello all, I am after some advice regarding a hall sensor type air flow meter. I know from experience that most hall sensor flow meters allow a bypass of fluid around the turbine/fan. However I would like to know what would happen if this was the case of the design below. Specifications...
  26. Fig Neutron

    B Why is there a reverse wind current inside my convertible?

    I was riding home with a friend in their convertible and found that, to my mild irritation, my hair was blowing forward rather than behind me. So, as any logical person would do, I stuck my head out the window to confirm that I wasn’t crazy and my hair should indeed be blowing backwards. After...
  27. T

    How to find the velocity of air flow around the aerofoil?

    Homework Statement How to find the velocity of the air flow around the aerofoil? Homework Equations U - freesteam velocity β - angle of wing camber The Attempt at a Solution To find the velocity of the air flow at each section of the aerofoil, am I right to say that the horizontal velocity...
  28. Fabrizio Vassallo

    Weight of a box with a flying bird

    Hello! This is my first post here, and I look forward to many more! This is a sort of riddle I was told today, and left me full of doubts. So, the 'puzzle' was the following: " There's a man carrying behind his truck an enclosed trailer full of birds inside it. All the birds are standing on...
  29. bob012345

    How much air flow is required for lifting a wing?

    Given a wing that lifts a plane moving through it at velocity V, how do I figure the minimum volume of air flow necessary to lift the same wing if the plane is still and the air is blown over it? Would moving that volume of air over the wing artificially require more power than what is required...
  30. B

    Why Does Closing My Door Increase the Breeze in My Room?

    Hi, I have a question about air flow. My room is located on the corner-end of my building, on the 7th floor. I have two windows, each one facing a different side of the building, and one of the windows typically produces the breeze, and the other never does. When the door to my room is closed...
  31. M

    Air flow velocity - big to small and vice versa

    Hi there, prob a simple question for you physics gurus, but this application is for a race car, and question relates to air flow velocity through a pipe, in particular exhaust and intake. Now, my thinking for the exhaust (push) is that by going from a small diameter to a large diameter will...
  32. L

    Hobbyist engine tuner/automath wanting to design & create....

    Hi all! I was a member here 10+ years ago and tended to lurk in the shadows but not really post much, either feeling I didn't have too much to add and also tending to find the answers to questions I was looking for already - however for some reason I've been pruned and without being a member I...
  33. P

    Steps to calculate Air Consumption of a Pneumatic System

    Hi there, I'm new to this forum and this is my first post so nice to meet you all! Since English is my second language, I apologize for some odd sentences. I'm a 4th year university student and currently has an internship in a Press Shop of a car manufacturer in Thailand. The project has been...
  34. Y

    Why does my room have better air flow when the door is almost closed?

    Hi, I have a question about air flow. My room is located on the corner-end of my building, on the 7th floor. I have two windows, each one facing a different side of the building, and one of the windows typically produces the breeze, and the other never does. When the door to my room is closed...
  35. X

    How does a pressure/temperature difference cause a force?

    Hello. I am inquiring about how a pressure difference between a hot room (roughly room temperature) and a cold room (roughly the temperature of a standard refrigerator) can cause a force inside the cold room when exposed to its hotter counterpart. More specifically, I would like to apply this...
  36. S

    What is the speed of air flow in a pipe driven by compressed air for 12 minutes?

    Homework Statement A tank with a 25.5 litre capacity contains air compressed into 355 atmospheres used to drive a torpedo by expansion into an engine via a pipe of diameter 0.08cm. A mechanism ensures that the gas flows to the engine at a constant rate and any cooling of the air during...
  37. H

    B Propeller thrust in restricted air flow environment

    looking at where to start understanding how the thrust/lift generated by a specific propeller (hypothetical one) changes as a function of surrounding air pressure. obviously the lift will go to zero as air pressure decreases. as pressure increases, modeled by say mounting the propeller inside...
  38. JCB123

    I Air flow from atmosphere into a tank

    Hi, I have a tank of air which has been depressurized to 0.2bar (absolute) via a vacuum pump, where air can be let in from atmosphere through pipework controlled by a valve. What would be the equation I can use to determine the flow rate into the tank with time? As the flow rate is determined by...
  39. Z

    Bernoulli vs Newton - air flow characteristics

    One thing that has always puzzled me is the fact that in a venturi, air accelerates as it approaches the narrow part of the structure. there are those that argue with the fact that pressure has to raise first , because as we all know, acceleration has to be caused by an increased force (...
  40. I

    Air flow: pressure increase over a constriction and fan

    Homework Statement So a fan sucks air through a pipe, and the outlet is near the fan, and thus the inlet where the air starts to travel is furthest away. If the diameter is constant the speed would be constant due to the continuity equation, and I assume we neglect compression effects in...
  41. A

    What is the Best Control System for Compressed Air in a Drone?

    Hey, I'm working on a project to build a drone which is powered through air jets. The drone needs a valve control system which can control the flow rate (hence the thrust) going to each nozzle in order to adjust it's altitude and stabilty. I need to set up a circuit which can electronically...
  42. G

    Compressible air flow from a tank through a regulator

    This is probably a simple question but I am really struggling as to where to start. We have a tank of compressed air, Volume of tank (V1) = 0.2litres Pressure of tank (P1) = 206.8 bar Regulator Pressure (P2) = 58.6 bar I would like to find the volume of air that can pass through the regulator...
  43. jsg94

    Determine air flow rate from pressure drop and hose diameter

    Good evening everyone, I have a pressure meter from where we determined a pressure drop of 5.5 psi (Initial pressure 45.5 psi, final pressure 40 psi). The working fluid is air. The diameter of one of the hoses that is connected to the pressure meter is 1/4". I wasn't able to take a picture of...
  44. Chevreuil

    4 stroke engine exhaust fed to high air flow

    Hello, So say that I have a small four stroke engine that is designed to be kept static at ground level. I then take this engine and mount it to a small air plane, feeding the engine with either still air from inside the cabin (cargo) or the outside wind. The exhaust is fed out to the wind...
  45. Chemchampa

    What is the mechanism of heat transfer and air flow in coffee roasters?

    Hello, I have here a complex question. My background is Chemistry and Optoelectronics. I wasn't the best when we were studying Thermodynamics at uni so I have some knowledge-gaps. Anyways, here is my problem. Can somebody explain me the whole process of the convection in the coffee roaster. So...
  46. J

    Pressure required for air flow through nozzle

    I need to know the maximum compression speed that can be applied to a rectangular bladder which has a open air port that will avoid rupturing the bladder. The bladder is 40" wide, 100" long, and 10" tall. The compression equipment is a large metal panel that is larger than the surface area of...
  47. Firasf1dream

    Need help in calculating Engine Air Flow and Specs Explanation

    hello everyone, i hope you're doing well, i am new to this forum so i am not sure if this is the right place for my question what i am doing is trying to calculate the air flow needed for intake of an RC engine Zenoah G320RC in the attachment files, it's a pdf for the info about the Standard...
  48. F

    Calculate Pressure Drop of Air Across an Opening

    How do I determine the pressure drop of air across an opening? For example if I have 3,000 L/s (3 m3/s) and an opening of 8.4 m2 I know the velocity is 0.4 m/s. If the free area is 80%, the velocity increases to 0.45 m/s. What I'd like to cal is the pressure drop in each case. Cheers
  49. L

    How can I accurately measure the mass air flow in my intercooler heat exchanger?

    Hey guys, long time reader first time poster. I'm undertaking a project in partial fulfillment of my Mechanical Engineering degree with regards to the cooling of an intercooler heat exchanger with an exterior water spray. basically i have an intercooler and i am using a hair dryer to supply a...
  50. M

    Heat Transfer Coefficient -Air Flow onto perpendicular plane

    Hi All, I have a situation were I need to evaluate the heat transfer coefficient of a horizontal surface. The surface has tubes within although I first used "flow across a bank of tubes", this has been untrue due to the air flow coming from above the surface flowing vertically (and...