Air pressure and velocity in a pipe

In summary, the person is seeking to determine the air velocity and pressure at the end of a 5m hose supplied by a centrifugal fan. They have provided information about the fan, pipe, and air, and are wondering if it is possible to estimate the velocities and pressures and what calculations would be needed. They also mention the possibility of back pressure in the pipe due to resistance.
  • #1
confused slug
8
0
This is NOT homework. The fan is a Crary Fan and the hose is Oregon PU used to distribute particles. I have tried a number of 'online' calculation sites but they return either conflicting results or 'infinite' values!


Dear All

I am trying to determine / estimate the expected air velocity and pressure at the end of a 5m long hose, supplied by a centrifugal fan coupled directly onto the hose. The information / assumptions i have are;

Fan System
Static Pressure: 4kPa
Volumetric Flow: 40m3/min

Pipe
Length: 5m
Diameter: 110mm
Roughness: 0.05mm
Minor Loss Coef: 0.1

Air
Temp: 15°c
Density: 1.1 kg/m3
Kinematic Viscosity: 10 E-6 m2/s


From this is it possible to estimate the velocity of the air stream at the start of the hose and at the and (v1 & v2) and the associated pressures (p1 & p2)? If it is ,what are the calculations?

I assume that due to the resistance caused by the pipe there will exist a 'back pressure' in the pipe. What would this pressure be 1m from the fan outlet (1m down the pipe).


Thanks
Confused
 
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  • #2
This flow can be quantified using the Darcy-Weisbach friction factor vs Reynold number correlation. It may be necessary to take into account compressibility if the fluid is a gas, in which case one would be solving for the pressure squared rather than the pressure to the first power.
 

FAQ: Air pressure and velocity in a pipe

1. What is air pressure in a pipe?

Air pressure in a pipe is the force exerted by the air molecules on the walls of the pipe. It is measured in units of pressure, such as pounds per square inch (psi) or pascals (Pa).

2. How does air pressure affect the velocity of air in a pipe?

The air pressure in a pipe can affect the velocity of air by creating a pressure gradient, which causes the air to move from areas of higher pressure to lower pressure. This movement of air results in a change in velocity.

3. What factors can influence air pressure and velocity in a pipe?

Some factors that can influence air pressure and velocity in a pipe include the size and shape of the pipe, the temperature and humidity of the air, and the flow rate of the air. Changes in any of these factors can impact the air pressure and velocity in a pipe.

4. How is air velocity measured in a pipe?

Air velocity in a pipe can be measured using a device called an anemometer. This instrument measures the speed and direction of air flow by sensing changes in air pressure and converting them into a velocity reading.

5. What is the Bernoulli principle and how does it relate to air pressure and velocity in a pipe?

The Bernoulli principle states that as the velocity of a fluid (such as air) increases, the pressure decreases. This principle applies to air flowing through a pipe, as the air velocity increases, the air pressure decreases. This relationship between air pressure and velocity is important in understanding the flow of air in a pipe.

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