Airflow Definition and 103 Threads

Hello, I have question about vent for tube that is 5" in diameter and 160ft long. Could 5" vent push/extract air to/from tube above? If possible, how much CFM should vent have? Thx 😊

Hi friends. Nice to be a new member of that forum. Content and member knowledge are impressive. I was reading a lot about fan types and airflow physics when pulling and pushing air. My main idea is to do some test with different configurations of my setup. I'm going to measure temperature in...

Writing from Cuba. This is canoeing: There are multiple causes for it but the one I'm interested in is when it is caused by directional air flow (AKA wind). If a breeze is blowing across my stogie from the same direction for an extended duration, one side will burn down much more than the...

A while back, you guys helped me out with a project on my '69 Camaro. It was all about the Bernoulli principle and airflow taking the path of least resistance. I'm happy to say that the lower closeout panel I built (see pix below) seems to have done the trick as the car I no longer having any...

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...

Does wing really fly in already downward moving air? Video from 18:15 - 19:40

How did you find PF?: Google search Hello everyone, thanks for letting me join. I am hoping that some of you would be intrigued and help me design a new motorcycle airbox for a charity moped racing series here in the UK. We take the most common motorcycle ever made the Honda c90 and race it...

Just a few quick questions regarding airflow, mostly in connection with motors creating the airflow, like pc fans, vacuum motor, air going into a car engine through air filter, etc. 1) Adding more filters increases the availably surface through which the air can flow, therefor reducing the...

I was wondering how fast you would need to spin a drone propeller to lift x amount of force and mostly how the rpm of the propeller affects the force of the airflow it releases. I’m incredibly new to physics in general and you can take everything I say with a grain of salt. I have no actual...

I know the Bernoulli equation for calculating the air velocity through a pressurized hole, but I am wondering if one hole of a given area behaves the same as multiple holes with the same total area. The Bernoulli equation doesn't make a distinction. Background: As a personal 3D design and...

The other day I read on a website that a lower evaporator airflow causes lower low pressure side saturation temperatures and higher delta T on an air-conditioner. Now I think I know why a lower evaporator airflow would cause a high delta T. If there is less air moving over the evaporator, the...

I'm using a stainless steel pan and a fan to cool my coffee down as quickly as possible. Usually, I have the fan blowing down towards the coffee, but this morning I flipped it over to suck the heat out of the coffee and I'm wondering which of the two is the most efficient, especially as, in the...

the tldr covers everything I think. I don't expect there will be an analytic solution here lol. but I don't even know where to even begin formulating this problem mathematically. I assume I should find an expression for the initial lift on the blades, multiply by 3 and then model it as a...

Question is indeed very short and clear, but answer will eliminate many doubts and misleading conclusions. Theory predict downwash that will cause reduction in airflow angle,this we call effective airflow(airflow with lower angle compare at geometric AoA). Does wing of aircraft during flight...

TL;DR Summary: Using the surrounding airflow to deduce the physics around UAP/UFO Now that NASA is in the mix for investigating UAP/UFOs - I started wondering at what their approach might be. I'm thinking they might be able to work from the outside in, toward the object/sensor(y) artifact...

This question is about sail aerodynamics, more precisely what cause spanwise airflow at the sails? When sailing close hauled,at the jib windward middle and top tell tales stream up or at 45 degress up, all others leeward and bottom windwards tell tales stream horizontaly. 1. What cause airflow...

We have a new AHU installed for a Compounding Pharmacy. The unit has two return fans and two supply fans. They are installed in parallel and are powered by VFDs. In the event of one fan failing, the other fan is supposed to speed up to maintain static pressure in the clean environment. This...

Happy Holidays! I saw your posting on airflow thru mesh screen and went to Perry's looking for answers. I haven't found what I'm looking for yet and was wondering if you can help? Our problem concerns bees coming down the chimney and how to stop them. We installed a Lymance chimney damper with...

Hello, I am working on a project that involves air at high pressure and temperature flowing through an orifice (valve) from one container to another. For each container, the volume, temperatures and pressures are known. The valve diameter is also known, and the fluid is air (which can be...

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...

I have a fan that consumes 60 W and blade diameter is 12 inch. If it's just 60% efficient, then the velocity of air coming out of it is around 9.5 m/s. I also have a nozzle inlet of which fits the fan and the diameter at the throat cum exit is 3.5 inch. I want to know how to measure the velocity...

Typical box fan+air filter setups use axial consumer-grade fans designed for providing maximum air flow at low power consumption. These fans do not provide sufficient air flow at the high static pressure requirements typical of air filters. The air filters DIYers use are high Merv(e.g Merv 13)...

We know blower compressors i.e. compressors that use a blower to create high velocity for injecting air/fluid to higher pressure and that's available in market. Now, suppose we have such a blower type compressor that can create a flow of air/gaseous fluid of 337 m/s. Question is, what maximum...

A melodica is a wind instrument that has a keyboard (piano-style, not computer-style). The player blows into the instrument. When a key is pressed, a passage opens. The air flows over a brass reed, making it vibrate. The reed sits in a channel a hair's-width bigger than the reed. The air flows...

http://mccabism.blogspot.com/2017/08/curved-flow-and-arrows-a3.html "The nose skirts on the Lotus 80 and Arrows A3 would have suffered from the fact that a Formula 1 car has to generate its downforce in a state of yaw. Thus, in a cornering condition, a car is subjected to a curved flow-field...

Hi team, I am after some assistance. When I am amending the primary airflow temperature on diffusers from 22°C to 13°C, it is my opinion that all the Draught rating (DR) and comfort criteria calcs will all change as the air will become more dense. Is this correct?

(Sorry for the really basic question. Been 20 years since high school physics and I've been working in a different industry)

Elevators are a problem in this post COVID world. It is impossible to maintain social distancing while also meeting the passengers-per-hour needs of the building. Skyscrapers without efficient elevators are not practical. The new social etiquette says that it is OK to shut the door of the...

I am in pharmacy school and my professor recently went over lung diseases with us. An important (and cheap) tool that many patients can use to detect whether their lung function is declining is a peak flow meter, which tells the patient how much air they are moving when they exhale with as much...

Why the air splitted at point a of aeroplane wing's cross section meet at point b simulatneously,

Hi, First of all I am sorry if I post in an incorrect thread. I can ask my question in PC forums but I thought it probably better if I ask in physics forum. So, I am trying to make the temperature in my PC better by adding additional fans, however I can't really place the fans in whatever...

What-will-happen-if-the-air-entering-to-the-intake-manifold-is-smaller-than-the-air-entering-the-cylinder-from-the-manifold? the following expression is the rate of change of the manifold pressure interms of the mass flowing to the manifold and the mass of air flowing to the cylinder from the...

I am talking about low wing single engine WWII fighter types. In particular, I am interested in accelerated propeller airflow through the transition/curvature of the prop slipstream spiral distribution around the wing, from being partly below, towards mainly above the wing. This as the wing's...

Hi everyone! For the past week I have spend a lot of time thinking about how de Laval nozzles work. But before I convince myself that I have understood it, I want to make sure that the (simpler) scenarios I describe below are correct. Setup: We have a long pipe with constant radius r = 1...

Hello, I need to extract a flammable gas (hydrogen) from a lead-acid battery room. Is there a way to use a regular fan without putting it in the airflow (hence to produce some degree of negative pressure in the battery room)? I've made a little sketch to illustrate the actual situation...

Hi. Is there any way to calculate airflow out of a tube (into atmosphere) with only the pressure and cross sectional area of the tube?

I'm making a ventilation system with a fan that will blow air through a 1700mm long pipe that has a 45 degree bent in the middle. I should decide on a pipe diameter of 125mm or 160mm. Also I need to choose between 3 different fans that has the following specs from the manufacturer: 120mm fan...

HI all. A bit out of my depth here...degree is in chemistry, but that's not helping me with the real world problem I'm trying to solve. I have a single air inlet that's being used as a cooling stream. It is channelled by a duct (or ducts, there are a few available designs) onto a piece of work...

mass of air X velocity = mass of man x gravity (10000)x(v)=60x10 velocity=600/10000 how come velocity is so less? I am still in school so forgive me if my calculations look stupid.

Homework Statement 1.Since the roadster seats only two people, it has only two side windows--one on each side. Each window is aligned squarely on the vehicle, so air can flow straight past the window as the vehicle heads forward. However, the air flowing around the roadster's windshield has to...

Hi, I am new to the use of forums and have no experience in airflow but I was looking for some help with the calculation of the gas flow through the main stack of a cement plant, the measurements I have at the moment are as follows Velocity= 12.5m/s Temperature= 120°C Differential pressure=...

This is only a semi- serious thread, since I suspect there's a simple back-of-a-napkin calculation that shows this to be infeasible. The idea is the following: a lot of a car's efficiency gets lost in the form of air drag, I.e. forcing the air to go around the car. Could one upscale a...

I have a weird question here. At what speed does air flow from a pressurized container at one atm into vacuum (rupture in ISS for example). I was watching the Martian and I wanted to see how much deltaV Mark Wattney can get by puncturing his suit, so I did my homework and saw that the spacesuit...

Homework Statement Engine needs airflow of 1 m3/min (std. p=101.325kPa, T=293.15K) it is suplied by machine working at p=700kPa. Homework Equations How big flow is requied from the machine to supply engine with air? The Attempt at a Solution Tryed using ideal gas law pV=nRT 1) I found out n...

Are these two terms synonymous? or not

This question is regarding the general fluid dynamics involving warm air advection aloft a persistent cold air pool in a small basin that is recessed in a horizontal planar surface. For scale, the basin has a compound parabolic shape, with a 30° viewing angle, a .146m radius at the base, a .292m...

I have a similar question as others but I felt wrong taking over their threads. The project is an casing for electronics that will be outside all year around. Built out of metal. This means rain, sun, snow. -20c to +35c. The electronics inside works only in 0c-45c and 10%-80% humidity. I want...

Hello there I'm having real difficulty with a problem to do with air cylinders and would really appreciate some help. I'm attempting to replicate the human breathing system in a simplistic form but I'm having trouble calculating the force required to provide the correct airflow rate at the...

Blocking the intake of an air flow station I built results in the FPM shooting up along with the vacuum. ie: wide open both ends 4" pipe with inline fan reads . 5" wc / -190 pa / 3700 fpm on instruments monitoring intake pipe. Blocking the intake increases both the vacuum to -470 pa and...

Hi. First post so I hope I have the correct thread location. I am reverse engineering a 40+ year old vertical slide carburettor design i.e. the venturi is horizontal. The current spray nozzle protudes vertically into the airflow but is straight sided and flat across the exit. Option 1...