Calculating Air Flow Within a Pipe

In summary, the conversation discusses the effects of applying suction at one end of a pipe with a variable hole size. The pressure gradient within the pipe is linear and the centrifugal forces do not play a role in this scenario. Increasing the hole size can lead to a decrease in pressure losses and an increase in flow rate. A diagram is provided for reference.
  • #1
funbar
3
0
Consider a pipe. One end of it (hole) is malleable, in that we can make it larger so that the cylinder adopts a conical shape (yet the other 'hole' does not change).

If one were to apply suction at one end of the pipe, with respect to air flow, how does the pressure gradient vary within the pipe as the variable hole grows larger?

In what capacity will centrifugal forces act upon the air flow? (does this suggest a vortex?)
 
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  • #2
Welcome to PF.

Could you provide a diagram please - it is very difficult to understand what you are trying to describe.
 
  • #3
Seems like a horn.
 
  • #4
Cross-section (pipe is solid & hollow).

[PLAIN]http://img138.imageshack.us/img138/5590/pipex.png

Assuming suction on the left end, how can we expect the airflow to change as x varies?
 
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  • #5
Any ideas?
 
  • #6
funbar said:
Cross-section (pipe is solid & hollow).

[PLAIN]http://img138.imageshack.us/img138/5590/pipex.png

Assuming suction on the left end, how can we expect the airflow to change as x varies?
Yes, as you increase the inlet and the size of most of the pipe, losses will drop so the flow rate will increase as x increases. The maximum flow rate is when the static pressure of the suction is all converted to velocity pressure at the outlet Y and other pressure losses are near zero.
If one were to apply suction at one end of the pipe, with respect to air flow, how does the pressure gradient vary within the pipe as the variable hole grows larger?
Through the pipe, you have an inlet velocity that gives you a certain velocity pressure at the inlet and static pressure is atmospheric pressure, then a linear static pressure gradient toward the outlet (suction end). Velocity pressure is constant throughout

Through the cone, the static pressure again starts at atmospheric and the velocity pressure is near zero, then the velocity pressure increases through the cone and static pressure decreases.
In what capacity will centrifugal forces act upon the air flow? (does this suggest a vortex?)
None that I can see - I don't see a rotational component here.
 
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1. How is air flow calculated within a pipe?

The air flow within a pipe is typically calculated using the Bernoulli's equation, which takes into account the pressure, velocity, and density of the air within the pipe. Other factors that may affect air flow include the pipe diameter, length, and roughness.

2. What is the formula for calculating air flow within a pipe?

The general formula for calculating air flow within a pipe is Q = AV, where Q is the volumetric flow rate, A is the cross-sectional area of the pipe, and V is the air velocity. However, for more accurate calculations, the Bernoulli's equation or other specialized equations may be used.

3. How does pipe diameter affect air flow?

The diameter of a pipe can have a significant impact on the air flow within it. A larger diameter pipe will have a higher cross-sectional area, allowing for more air to flow through at a given velocity. This means that larger pipes can handle higher air flow rates than smaller pipes.

4. What is the importance of knowing air flow within a pipe?

Knowing the air flow within a pipe is important for a variety of reasons. It allows for proper sizing and selection of equipment such as fans and blowers, ensures efficient and effective ventilation in a system, and can help identify and troubleshoot any issues with the system.

5. How can factors such as temperature and humidity affect air flow within a pipe?

Temperature and humidity can affect air flow within a pipe by changing the density of the air. Warmer air is less dense, meaning it will have a lower mass flow rate for a given volumetric flow rate. Humidity can also affect the density of air, as moist air is typically less dense than dry air. These factors should be taken into account when calculating air flow within a pipe.

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