Finding volumetric flow rate from pressure?

In summary, the conversation discusses the possibility of calculating the volumetric flow rate from instantaneous pressure in order to run a CFD simulation of the intake system in an engine. It is mentioned that more data and assumptions are needed, such as the size of the intake port and whether the flow is laminar or turbulent. The conversation also touches on the importance of obtaining the intake area and cylinder geometry in order to determine the appropriate formulas for calculating the flow rate.
  • #1
U6an
3
0
Hello everyone,

I am quite new to Fluid dynamics, so I would like to ask for your help.

Is it possible to calculate volumetric flow rate from the instantaneous pressure?

We need to know the flow rate of the air entering the cylinder in the engine due to the suction pressure. It is required to run a CFD simulation of the intake system.

Regards,
U6an
 
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  • #2
U6an said:
Is it possible to calculate volumetric flow rate from the instantaneous pressure?
Yes, but you need more data and some assumptions.
U6an said:
We need to know the flow rate of the air entering the cylinder in the engine due to the suction pressure.
You need the size of the hole the air enters by. You also need to specify whether you assume laminar air flow or turbulent.
 
  • #3
Svein,
Thank you for you reply.

Could you please tell me if you mean the bore of the cylinder or the intake port diameter?
The flow will probably be turbulent, but I am not sure. Could you also give me a hint on how can I know if the flow is turbulent or not?
 

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  • #4
U6an said:
Could you please tell me if you mean the bore of the cylinder or the intake port diameter?
I assume that the air enters through the intake port, so that is what is needed.
U6an said:
The flow will probably be turbulent, but I am not sure.
I agree that it is probably turbulent (if the air entering the system makes a noise, it is turbulent).
 
  • #5
Svein said:
I assume that the air enters through the intake port, so that is what is needed.
Indeed, air enters the cylinder through the intake port :)

Thank you for giving a hint on the noise ;)

Providing I will obtain the intake area as well as the cylinder geometry, what steps should I take then? Are there any certain formulas for that?
 
  • #6
U6an said:
Providing I will obtain the intake area as well as the cylinder geometry, what steps should I take then? Are there any certain formulas for that?
Yes, but I do not remember them (I did some work with air pressure across a small valve - 35 years ago).
 

Related to Finding volumetric flow rate from pressure?

1. How is volumetric flow rate related to pressure?

The relationship between volumetric flow rate and pressure is described by Bernoulli's equation, which states that as the pressure increases, the velocity of a fluid decreases, resulting in a lower volumetric flow rate.

2. What is the formula for calculating volumetric flow rate from pressure?

The formula for calculating volumetric flow rate from pressure is Q = A * v, where Q is the volumetric flow rate, A is the cross-sectional area of the pipe, and v is the velocity of the fluid.

3. What units are used for measuring volumetric flow rate and pressure?

Volumetric flow rate is typically measured in cubic meters per second (m3/s) or liters per second (L/s), while pressure is measured in pascals (Pa) or pounds per square inch (psi).

4. How does the viscosity of a fluid affect its volumetric flow rate at a given pressure?

The viscosity of a fluid is a measure of its resistance to flow. As the viscosity increases, the fluid's ability to flow decreases, resulting in a lower volumetric flow rate at a given pressure.

5. Can other factors, such as temperature, affect the relationship between volumetric flow rate and pressure?

Yes, temperature can also impact the volumetric flow rate and pressure relationship. As the temperature increases, the kinetic energy of the fluid molecules increases, resulting in a higher velocity and therefore a higher volumetric flow rate at a given pressure. Additionally, changes in temperature can also affect the viscosity of a fluid, which can further impact the volumetric flow rate.

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