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Questions tagged [airflow]

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19 views

Air flow through non-uniform size Duct with Holes

[!2nd attached image is the answers i got from Physics Stack Exchange website. Unfortunately, the answers provided their were not enough to resolve the problem, so came here hoping for a detailed ...
0
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0answers
29 views

Turbulence strength from turbulence intensity?

I do not have a lot of knowledge in aerodynamics but I need to be able to derive turbulence strength (Cv2 and Ct2 - so called turbulence structural parameters I think) from turbulence intensity. Does ...
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2answers
54 views

In an air conditioner, how does the released air get cold so quick?

As I understand from reading about air conditioners is that the way they work is that air sucked in from the room is passed by the cold evaporator pipes and then the air is released again. My ...
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1answer
22 views

How to determine ideal flow path length for specified pressure drop

I have designed a flow resistance element and I would like to be able to keep the total pressure drop across the element to < 5.0 inches of water (from 5cc/min to 5,000 cc/min). I have run some ...
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18 views

Estimating Static Pressure @ Target Airflow (boost fans)

How do I estimate a pressure/flow curve for a filter of specified area, efficiency rating, MERV and MPR?(Duct work is negligible) I am trying to pick an appropriately rated fan/fans to maintain a ...
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29 views

Can I lift 15 tons on air bearings with 0.2 kg air/s?

The air is at 13 kPa and 400 K. I can raise both the supply temperature and the pressure if necessary. No problem with that. I could get 1.7 kg/s for the air bearings, but I have no more air. I ...
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0answers
25 views

Is this is a valid estimation for the mass flow required for Hyperloop air-bearings?

In Hyperloop air bearings, the air escapes through the rear cross-sectional area of each ski, you know? Yes, there is a pressure differential, but the air comes out of the skis, crashes into the tube ...
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2answers
50 views

Would a plane lift from ground if in a free treadmill?

I was wondering if the force generated from the engines of a jet plane would lift it up from the ground if in a free treadmill. Would it take off?
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33 views

Flow Simulation for Laminar Flow in Annular Gap?

Would anyone be able to run an air flow simulation through the following geometry at 100 cc/min? I'm curious if any dead spots occur and if the geometry of the annular gap will produce laminar flow. ...
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0answers
24 views

Use of Absolute vs. Differential Pressure Transducers to Calculate Flow Through Annular Restriction

If using a laminar flow element, in conjunction with Poiseuille's equation, to calculate mass and volumetric flow rate, what would the benefit be to using two absolute pressure transducers to measure ...
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0answers
35 views

Is it possible design a portable high powered vacuum cleaner from a 12V DC motor?

I am currently designing a device that can pick up 20 kid's plastic balls from one box and transfer them all into another box. I have decided to use a vacuuming method to vacuum up the balls as my way ...
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0answers
14 views

What pressure value to use for Poiseuille's equation?

If using a mass flow meter with a annular gap to produce laminar flow and the reading across the restriction is 871 Pa, is this the correct value to use for dP in the Poiseuille equation? Or must that ...
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0answers
31 views

Volumetric & Mass Flow Rate Through a Piston-Cylinder Annular Gap with Laminar Flow?

I am attempting to define the proper equations used to calculate both volumetric and mass flow (based on pressure differential) through a Laminar Flow Element. The element consists of a piston ...
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3answers
27 views

Is it possible to “expand” air flow area in a duct over a short distance?

Is it possible to increase an air column's diameter over a short distance? Let me explain: Imagine a small 10 cm electric computer cooling fan that's pushing air into a cone-shaped duct 20 cm long. ...
0
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1answer
131 views

Estimating fan CFM from RPM, HP, and diameter

I am trying to determine the approximate CFM of several axial flow fans being used in agricultural storage in the developing world. The only information the storers have is the power, RPM, and ...
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0answers
18 views

Chimney for lower electricity bill for airflow?

So there is a heat exchanger fan in a very airtight house. Would the fan consume less electricity, if it would blow out the used air not via the side of the house, rather via an unused chimney, ...
2
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0answers
22 views

How to balance flow and pressure in nitrogen purged chambers?

I have an instrument that is technically a humidity controlled chamber. It measures how much moisture is picked up by the sample through a microbalance(Zone 1). Nitrogen gas flows from zone 3 and ...
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2answers
30 views

Noise in centrifugal fan

I'm currently designing my own centrifugal fan for one of my projects, everything excluding the motor. My design is similar to the above just that the outlet is much shorter. The problem I'm facing ...
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2answers
174 views

Passing by a semi truck on a highway

So I’m driving down the highway in my sedan on a speed of lets say 60 mph. Why is it that my car sways just before it passes or it passes me? Almost always where the semis first tire is (closest to ...
2
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1answer
32 views

What is the difference in CFM, at a given static pressure, between a CPU fan and a Squirrel Cage Blower fan when moving air through ductwork?

I have a Delta ASB0912L DC Brushless fan. PDF here. In the datasheet it says, RPM 3800 CFM 67.80 IN H2O 0.302 On the blower, squirrel cage fan, Dayton from ...
4
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1answer
74 views

Will the airflow inside a vacuum hose keep a sphere centered inside of it?

Suppose you were to fasten a string to a ping pong ball, then fasten the string to a stationary object, and then use a vacuum cleaner with a strong vacuum to suck the ball partially into the vacuum ...
1
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1answer
61 views

What is the point of this valve that only allows air in and not liquid?

I'm looking at googles mocktails maker. And it puts 2 holes in a container. 1 hole is connected to a pump that will take water out and the other connects to a backflow prevention valve that only ...
3
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2answers
78 views

Will circulating air within a sealed ductwork system cause it to implode?

Referring to the pasted in ductwork diagram, if an inline ventilation fan with a high CFM airflow was used to circulate air within a sealed ductwork system, would the fast moving airflow result in a ...
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1answer
44 views

Air Cools As It Expands

What is the degree of cooling caused by air flowing from smaller diameter into a large diameter? How much does air cool as it expands? If the air inlet was the biggest hole on the right and the ...
1
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1answer
16 views

Variables Relating to Atmospheric Water Generation

I am interested in discovering a method to relate air flow to temperature reduction efficiency. The purpose of this is in application to atmospheric water generation. The apparatus will involve a ...
0
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1answer
26 views

How much cm needed for airflow? - optimal window shutter distance

I am thinking that air (if it is still) is a very good insulator. So why aren't we putting the window shutter far away from the window? It would have more air between the window and the shutter ...
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0answers
33 views

Choosing a blower for a Pneumatic Conveyor

Basically we are designing a pneumatic conveyor system for transferring 11 tons of beans per hour. We need to decide on the specifications of the blower. What are the calculations necessary to decide ...
0
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1answer
31 views

Calculating typical floor fan efficiency or dP? (Spec sheet too good to be true?)

Looking to purchase a fan with high velocity. Trying to make solid data driven decision based on specs. Found that most fan's of the 20" diameter variety are around 3000 CFM; however found one that ...
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3answers
50 views

Area ratio using Bernoulli's equation

I am using Bernoulli's equation in order to calculate a relative area between two points in a pipe. Problem is, based on the solution I have obtained, I end up with imaginary numbers and not sure what ...
-1
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2answers
76 views

Doesn't this fan spin the wrong way?

I have a fan on a stand, to circulate air in my home. The three fab blades are somewhat "D"-shaped, with one edge being rounded and one being straight-ish or even curving inward. Now, from my sailing,...
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0answers
19 views

How to analytically estimate the pressure loss through an liquid injector?

The simple orifice and a pipe have well-documented pressure loss calculation. But when an injector has complicated flow patterns, is it possible to break it down into simpler sections by which the ...
0
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2answers
39 views

Will a fan that is composed of several fans fixed inside rotating tube work?

I want to design a custom 3D printed fan that would be made of several axial fans that would be connected (fixed) to their cylindrical casing. I am planning to rotate the whole assembly (the cylinder ...
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0answers
29 views

Ventilation requirements of a closed housing of a video wall

Our company builds rather large video walls that are driven by computers next to them. In one of our current project the size of the installation is 21 55" displays side by side in portrait mode and 4 ...
2
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2answers
156 views

How to calculate added lift from ground effect

I'm trying to build a hovercraft of sorts, and I thought I'd take advantage of the ground effect. I've done some searches, but I can't seem to find any guides on the actual physics. How do I go about ...
0
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3answers
47 views

Ventilation setup high sleeper night cooling

I have a high sleeper in my room (width 3,70m, length 4,50m, height 3,30m) consisting of one large plane (yellow) and one window (darker grey). The plance leaves about 80cm space to sleep. The door (...
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2answers
51 views

How does a Vibratory Pump (“Schwingankerpumpe”) work?

in my aquarium Ive got a little pump for bubbling air through the water so it is substained with enough oxygen. Internaly the pump works fairly similar to old door bells, where the mains is flowing ...
1
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1answer
32 views

AirFlow Measurement

I'm a software developer, who wants to create a monitoring system for an industrial airflow system. The airflow of the system is huge - between 15 and 20 cubic liters per minute. Here is my problem, ...
0
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2answers
47 views

Heating the air inside a turbojet instead of combusting it

Would an aircraft that uses propellers for movement but with a turbo jet like structure where the ignition chamber only heats the air a bit, similar to a hair dryer instead of releasing fuel and ...
3
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2answers
66 views

Compressing the air thrusted by an aircraft's propeller through a cone like tube

If I had an aircraft that used propellers for movement and took the air from the front running it through a tube that gets very small towards the end, would it have any impact on the speed? Would the ...
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0answers
260 views

What's inside a peak expiratory flow meter, and what's the difference with an anemometer?

The peak expiratory flow meter is usually used to manage asthma. I wonder what's inside it and how can it measure peak flow? What's the difference between this and an anemometer? Can an anemometer ...
0
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1answer
26 views

where to find / what to call a 3/4 inch air valve that can be opened/closed electrically? [closed]

I'm looking for something like this air valve: (as discussed in https://engineering.stackexchange.com/a/12404/12007) But I need to tube to be wider (3/4 in), the tube to be shorter (the shorter the ...
0
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1answer
38 views

Defining fresh air rates for sizing heating coils

dear StackExchange colleagues; If I want to find the fresh air rate in kg/s and the supply rate in kg/s during winter and summer for the case below: DATA: Indoor condition all year = ...
0
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2answers
58 views

Fan placement effect on pressure in chamber

I am building an air-hockey table. Essentially, a rectangular wooden box with holes on the top surface. I am fitting a blower fan on the bottom and wondering how affects the airflow, if at all. ...
2
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1answer
165 views

Cooling with fans in narrow space

I'm building a LED ceiling lamp. The idea is to mix different tones of white to get desired tone. It will initially have 120W LEDs and maybe more later It will probably never run at full power but I ...
0
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1answer
59 views

Do 36 inch diameter fans exist that push 25,000 CFM?

I own a warehouse that needs to push 25,000 CFM. I currently have an old warehouse exhaust fan that doesn't push anywhere close to this. The diameter of the fan blade is about 36 inches, but the ...
2
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1answer
800 views

How to calculate thrust from mass flowrate and velocity

How can I calculate thrust in Newton from mass flowrate and velocity? Please note,I have mathematical skills of 7 year old,the most complex task I can do is multiply and divide,I dont understand ...
3
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2answers
1k views

How to cool down a warehouse?

I have a warehouse ( 36m x 14.4m x 10m ) that I want to keep it under 30 degrees Celsius but everyday the temperature will goes above that. It has two turbine ventilator that I don't know the ...
0
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2answers
51 views

Room with computer racks, with or without ventilation

I have a room of computer rack that with 2750 watt power needs, which according to this site, I need 9000 BTU/h AC. I'm deciding if I should put a vent in the room or not. When there's a ventilation, ...
2
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2answers
80 views

Which fan / blower type should I chose?

Goal I am creating a project where I will need to move small beans around in turbulent air flow. I will have a heat source to which I do not want the heat to leave easily (I want the beans to be ...
-1
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1answer
35 views

what is the air speed of an HVAC central air system return at the filter?

I figured I would ask here before going out and buying an anemometer. for a 20" by 25" HVAC Return (or just state the size W x H that your data is based off). Assume a 3 ton system. what is the ball ...