What is Airflow: Definition and 110 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. Daren Zomerman

    Airflow on/around quadcopter drone

    Hello, I'm a journalist interested in using an air-quality sensor on a drone, and I'm wondering how the airflow will affect the readings. This would be assuming that I will use a DJ Phantom 2 quadcopter with a GoPro underneath, the drone specs can be found at this link. For the project, we...
  2. G

    Blocking Back Of Fan Creates Vacuum In Front?

    Hi there, I have recently observed a strange effect regarding a fan and was wondering if someone could explain what's going on. I have a 22cm computer case fan which I am using in a project. For my purposes, I had to partially tape over the back of the fan. I also put a large plastic jar lid...
  3. V

    Helicopter Airflow: Why Not Use Control Surfaces Below Rotor?

    Why control surfaces are not used below rotor in helicopters?
  4. P

    Detect Airflow + Regulate Temperature

    Heyo, first post here...! Sorry for my English and I will reword anything if it is needed. I've been struggling to solve this for a few days, please help me with some insight or intuition. I have application with a a heating element leading to little ceramic crucible, there is an airflow in and...
  5. D

    Airflow and hair dryer efficiency

    Homework Statement Can the power efficiency of the domestic hair dryer be improved by reducing the heat energy and increasing airflow? Homework EquationsThe Attempt at a Solution
  6. D

    Airflow Calculation for Baghouse Inlet/Outlet Temp 400F/210F

    The inlet temperature of a baghouse under negative pressure is 400 F and the outlet temperature is 210 F. The volume of air is 10,500 acfm. (baghouse is in poor condition). How do I determine the actual volume given this information?
  7. S

    Turbine: Straight or Rotational airflow?

    I'm working on a project now and I'd like to know which type of airflow would power a turbine faster/better straight or rotational? Or will rotational airflow even have any effect on the turbine...? P.S. When I say rotational airflow, I mean circular airflow that rotates in the same direction...
  8. T

    Calculating Force and Efficiency of Fans Using Airflow Measurements

    Hi, I am doing an experiment where I am measuring the airflow readings (m/s) of different fans. I then was hoping to use this to work out the force and then from that the power to compare the efficiencies of the different fans. I was wondering if anyone had any suggestions for what equations...
  9. T

    When will an airflow cause whistling?

    Is there any good approach to determining if an amount of air passing through a given slit or gap will cause a whistling sound? I'm unsure with what shapes whistling might become an issue, and also at what air velocities.
  10. N

    How Do You Calculate Air Pressure with Varying Flow Rates and Orifice Sizes?

    I have a basic airflow question and my mind is in the fog. I'm trying to find the air pressure at a known flow rate and orifice size but I'm having issues with the unit conversions. I'm using Bernoulli's equation Pressure = 1/2 x Air Density x Flow Rate/Area. My Flow Rate is in L/M and the area...
  11. N

    Airflow Turbulence at carburettor flange

    Hi Guys/Girls, Please may I seek your collective minds for help? I have an issue with poor mixture distribution from a carburettor that uses a spray bar and throttle slide (known as a Throttle Body Injector TBI) The holes in the spray bar are at the side of the spray bar in full rich, the...
  12. B

    Airflow modeling software on a small scale

    Hi there, I think this is in the right section if not please inform me and move my thread. I want to design and build a UAV in a copter format whether it be quad, hexa, octa, ect. I want to make a modeling software so that I can design the most efficient blade/motor for my specific needs. I am a...
  13. A

    How can I change the airflow under a hotel room door to the hall?

    I spend a lot of time in hotel rooms around the world and the US. The biggest problem I have is with cigarette smoke that comes into my room from the hallway and other rooms. The smoke generally enters my room through the space at the bottom of the door and through the space on the sides. I've...
  14. S

    Effect variable cylinder radius has on airflow

    Can someone shed some light on the following problem? I'm unable to get any traction on it as I know nothing about fluid dynamics (I'm a computer engineer). It's a problem I made up over a lunch discussion with a friend. I've illustrated it as folows:
  15. G

    Question about what happens to density of airflow through a heated tube

    I know the basic equations for airflow, but for some reason this question has been puzzling me: say you have a copper tube open at one end and connected to a piston cylinder system at the other. Air is drawn through the copper tube and into the cylinder as the piston moves from top to bottom...
  16. I

    Heat transfer and airflow question

    Hello everybody, I would like your comments on my findings and perhaps prompt me to look at relevant literature. Consider an enclosed airspace 1m length, 1m height, 0.5m width. At the center of its one 0.5 side a fan is drawing air out of the chamber through an aperture(steady, low air...
  17. K

    Cooling several rods by counterpropagating airflow

    Hi, due to the fact that its not my daily work, I how someone could help me to find a startingpoint, how to solve my problem: I want to cool down in a revolver like setup let me say 8 or more cylindrical rods in a continuous way by a counterpropagating airflow. the setup is shown in the...
  18. S

    Relationship between differential pressure and airflow through a filter

    I have a question regarding the relationship between differential pressure across a filter, the airflow through the filter and the size of the orifice that the aire is moving through. I would like to be able to predict differential pressure required to maintain a constant airflow as the filter I...
  19. M

    Static pressure and airflow at reduced fan speeds

    This is probably a stupid question but I've been going around in circles for a while now and have gotten myself completely confused. I have a fan and a pump, with performance charts (static pressure vs. air flow) for both. I need to try and determine flow rates for each device when run at...
  20. C

    Drag coefficient for plate perpendicular to airflow

    http://en.wikipedia.org/wiki/Drag_coefficient from wikipedia, it is written 1.98-2.05 for flat plate perpendicular to flow(2D) , but I have a differrent b/h ratio plate, where h=157mm and b=816mm , b/h=5.197 how to get the drag coefficient in this case? Thanks.
  21. Q

    Airflow design for generator box

    I'm making a portable generator box, and I'm currently designing the baffles. The design is quite similar to this: http://media.photobucket.com/image/hush%20box/Audiomechanic/ProjectorHushBox1.png There will be an extra wall on the left and right to accommodate louvres on the exterior...
  22. C

    How Does Airflow Through a Porous Wall Depend on Temperature Gradient?

    Homework Statement What we know is that we have two impermeable walls with a porous material inside (the porous material gives a simply restraining force proportional to the movement itself). we have a stationaly flow, so that dw/dt=du/dt=0. u and w are the velocities in the x (horizontal)...
  23. Y

    Radiator plenum, and venting for proper airflow

    Hello all, I am working on a kit car project that is coming together in a way I had never expected. That preliminary stats are way above what I had expected. So I am getting very excited about completing this project. However now I'm into engineering the radiator its plenum and its...
  24. X

    Airflow for engine room ventilation

    hello fellow engineers! i just started work at a marine company and was assigned to investigate on this formula. it is from ISO 8861 and used to caculate the airflow needed for heat evacuation in a engine room. this is the formula, airflow needed = (heat emitted from engine and all other...
  25. J

    Finding Software to Analyze Airflow over a Wing

    Hi guys, I need to test the airflow over a wing, I can't find any suitable software to do this job. I heard ANSYS is a good bet, but when I try I'm just lost... (not much exp with it). So anyone got any suggestions to analyse airflow of the wing.
  26. N

    Airflow inside a computer tower.

    I had a question and I figure you guys are the best for the task. I was wondering if theoretically you had a standard computer case, would you benefit by reducing open airspace in the case? Lets say just for example you could place a cube inside the case that doesn't touch anything, it just...
  27. D

    Airflow question regarding pipes of different diameters

    Hello all! I think I have come to the right place! Can someone explain to a mathematically challenged person such as me which of the following systems would create the most airflow: System #1 - System number one begins with (Point "A") a 1 foot long piece of 2" (I.D.) PVC pipe, connected...
  28. J

    When the motor is working harder, it needs to rotate faster.

    Hi all, long time reader first time poster here. I have a DCBL blower motor that has a fixed wattage at each speed level. I noticed that when I increase pressure (say from 0" SP to .1" SP) the RPM increase and the CFM (airflow) decrease. I understand that CFM will decrease with increased...
  29. S

    Exploring the Possibility of Car Lift Through Airflow

    When air flows over an airfoil, the air flows at the top flow faster than the bottom and hence creates a net pressure difference, and thus an upward force is applied on the wing. Thus the airplane lift from the ground and keep flying in the air. Now, imagine the side view of a car. Car...
  30. R

    Airflow velocity and temperature

    Homework Statement How does the airflow velocity vector get affected by temperature? Homework Equations The equation given is airflow velocity vector is directly proportional to sq.rt of temperature.It says in a jet engine the velocity vector at the compressor rotor blade inlet increases...
  31. S

    Combining of two gases within an airflow

    Homework Statement not really a question, just stuck with something. An airflow of 300 CFM has a contains 0.0387% CO2 (carbon dioxide-naturally occurring in air) flows through two ends of an rectangular open container from an exhaust fan located at the bottom. Within the container 100%...
  32. S

    Dyson Bladeless Fan, Inducted Airflow Propulsion, Personal Transportation

    I remember once observing a thread in a discussion forum by someone trying to build a backpack helicopter. Various people warned him about sprung-weight-vs-unsprung-weight, hazards of stability and flight control, etc. But ever since reading about James Dyson's bladeless fan and the...
  33. D

    Measuring airflow w/handheld anemometer

    I'm a building contractor looking for a way to measure the airflow (in CFM) of the vent fans that are typical in homes. The usual suspect is in the range of 80-150 CFM, has a squirrelcage fan installed in a metal housing that's installed in the ceiling, and a 3" or 4" round outlet that ducted to...
  34. B

    Airflow through a radiator with a restriction

    Hello, I have a question about airflow through a car radiator which has a plate on the discharge side with holes cut for fans. There are fans mounted on there but they aren't being used. And the car is moving. Would the airflow increase or decrease with the plate on there? We are having a...
  35. D

    Maximizing Mass Airflow in Internal Combustion Engines

    This inquiry is in relation to internal combustion engines. I am trying to figure out how to maximize the mass of air going into my engine. Because the more air that can get into the cylinder, the more power the motor can make. Now I've been researching Bernoulli's Principle and as I understand...
  36. F

    Cooling VW Bug Turbo Engine: Airflow thru Radiator?

    Ok hopefully one of you can help me out. I have a 68' bug that I recently converted to watercooled with a 2.0 vw engine with a turbo. I have been trying to figure out a way of effectively cooling the motor. I have a single row radiator approx 26'' X 20". I have mounted it in the back of the car...
  37. S

    Answer: "Airflow Around a Wheel: Why Do Hub Caps Bulge Out?

    Hi all, Just Wondering quickly, do the static hub caps on a Formula one car(say Brawn GP) bulge out slightly or are the flat and flush with the wheel? If they do bulge out, why does this produce less drag? Thanks Sean
  38. W

    Research Question Relating to Airflow and Airfoils

    I am currently a junior in high school in the full I.B. program and I am developing a research question for an extended essay. I have chosen to write an essay in the field of physics, and more specifically, aerodynamics. At the moment, I am trying to conceptualize a working research question...
  39. D

    Airflow dynamics over house and effect on roof vents

    I have been trying to find some information or study concerning a widely held idea concerning attic ventilation. Conventional wisdom states that when air passes over the ridge vent on the peak of a house, the resulting low pressure will draw air from the attic. The air that is removed from the...
  40. K

    Airflow around the wing - Dimensional Analysis

    img512.imageshack.us/img512/2985/42904009cw1.jpg Hey guys, I am a bit stuck on this prolbem. When it says identify the characteristic physical scales is this referring only to the length scales (l, h, b)? or is U, gravity, density and viscosity included as well? Now the only two...
  41. C

    AirFlow Calculations/ Anemometer anyone?

    AirFlow Calculations/ Anemometer anyone?? Hello all, I am trying to solve a problem with my anemometer. I am not sure if there is anyone here that has used one but here goes. My purpose is to calculate CFM of a particular AIR INTAKE of my truck. The problems lies in that CFM= Air Velocity...
  42. U

    Improving Airflow in a 2.5 Triumph Spitfire

    Hi. I am hoping for some advice on airflow...in particular, guaranteeing airflow to a rear mounted radiator, in my 2.5 Triumph Spitfire. I have read, about low pressure, and high pressure areas, although I am a little confused as to the area underneath the car. I understand that the lower a car...
  43. R

    Calculating Airflow and Pressure in a Fan-Funnelled Tube: Is There a Formula?

    Is there any kind of formula that exists or I can put together that will allow me to determine airflow from a fan being funneled into a tube that decreases in size over the length of the tube? Something specifically that would allow me to determine the air pressure (psi ?) coming out the end of...
  44. Bob3141592

    Airflow for Garage Woodworking Shop: Does Box Size Matter?

    I'm setting up a dust collection system for my garage woodworking shop. My plan is to build a manifold for various tools to feed into, with a single 4" exhaust port connected to the dust collector. This manifold is an 8" square by 5' box, with 4", 2 1/2" and 1 1/2" hoses going into it. All...
  45. F

    Question re: Aperture sizes for Resistance to Airflow

    Hi, I'm a final year Biomed. Eng. student currently working with a team on a project investigating Threshold Responses to Inspiratory loads, and their relation to sleep apnea. The key to this study is a box which provides the loads. It is a rectangular box containing 6 screens or...
  46. A

    From theoretical airflow speed of rotating propeller to a realistic value?

    Hey, Yet another propeller question on this board. I have done my research, both here & on google, but I cannot seem to find an answer. Lets say I have a motor on which I mount a propeller. This motor is static (not moving like on a flying airplane), so say its a small ventilator...
  47. P

    The Coanda Effect: Exploring Airflow Over an Airfoil

    What makes the air, flow much faster on top of the airfoil, when compared with the bottom surface? In engineering terms, why is there a relatively higher rate of change in velocity over the top surface? and is there any mathematical derivation/proof for coanda effect?
  48. C

    Modeling Filters in Airflow CFD: How to Simplify and Analyze

    If you wanted to model a filter in an airflow using CFD, how would you go about it? I imagine that an exact model of a filter would be way too complex to model and take vast amounts of time to solve, so there must be some kind of simplification? I was thinking that maybe some known properties of...
  49. Cyrus

    Thermo -- Airflow Analysis for Heating Ducts in an HVAC system

    2-48) The 60-W fan of a central heating system is to circulate air through the ducts. The analysis of the flow shows that the fan needs to raise the pressure of air by 50Pa to maintain flow. The fan is located in a horizontal flow section where the diameter is 30cm at both inlet and outlet...
  50. C

    How Does Box Design Affect Airflow and Velocity Through Multiple Outlets?

    Volume v's Mass airflow...? Can anybody possible help me to understand how the following situation is affected with respect to the Volume and the Mass Airflow/velocity? imagine a sealed square box. On the left hand side is a round inlet. at the bottom are 4 smaller outlets, in a roow from...
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