Calculating Pressure Distribution in a Nozzle for Abaqus

In summary, the conversation discusses ways to estimate the pressure distribution in a small convergent nozzle being modeled in Abaqus. The speakers suggest using conservation of mass and Bernoulli's equation, but also mention the possibility of the flow being compressible and making assumptions. The conversation ends with a question about converting CFM to velocity and determining if the flow is compressible.
  • #1
BSids
8
0
Hey all,

So I have a small convergent nozzle that I'm modelling in Abaqus and I'm wondering how I could work out the pressure distribution so I can apply the correct load. The problem is I only know the pressure being fed to it by air compressor. Is there a way to use Bernoulli s or some other method ? Can I make assumptions for the velocities or maybe even find general info on compressor and assume same?

Also considering the size of the nozzle is only about 30mm would I be as well to set the load as a uniform pressure?

Thanks!
 
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  • #2
You could get a decent estimate using conservation of mass and Bernoulli's equation.
 
  • #3
boneh3ad said:
You could get a decent estimate using conservation of mass and Bernoulli's equation.
Thanks for the reply. How would I go about doing this as I only know the pressure is 15 bar?
 
  • #4
Do you know how fast it is moving at 15 bar?
 
  • #5
boneh3ad said:
Do you know how fast it is moving at 15 bar?
No I don't although I could probably take a value from a compressor data sheet and assume the same?
 
  • #6
The first think you need to do is figure out whether the flow can be assumed incompressible or not. If it is incompressible, you can just use conservation of mass and Bernoulli's equation. If it is compressible, you will have to make a few assumptions.

If it is compressible, it's probably easiest if the incoming speed is slow enough that you can treat it as zero. If it is incompressible, the mass is easier but you will need to figure out what flow rate you have moving through the system so you can convert that to a velocity and then a pressure using the Bernoulli equation. Even then, it's just an estimate since you are going to be ignoring the effects of viscosity.
 
  • #7
boneh3ad said:
The first think you need to do is figure out whether the flow can be assumed incompressible or not. If it is incompressible, you can just use conservation of mass and Bernoulli's equation. If it is compressible, you will have to make a few assumptions.

If it is compressible, it's probably easiest if the incoming speed is slow enough that you can treat it as zero. If it is incompressible, the mass is easier but you will need to figure out what flow rate you have moving through the system so you can convert that to a velocity and then a pressure using the Bernoulli equation. Even then, it's just an estimate since you are going to be ignoring the effects of viscosity.

Hey, thanks for the help. I got a CFM value from the compressor data sheet of 5.8. I converted it to 0.002454 m3/sec and then that to 195 m/s by dividing by the csa. Are my maths right here? That would give a mach of 0.57 and so it must be compressible right?

Thanks again.
 
Last edited:

1. What is the purpose of calculating pressure distribution in a nozzle for Abaqus?

The purpose of calculating pressure distribution in a nozzle for Abaqus is to understand how the fluid pressure changes along different sections of the nozzle. This information is important in designing and optimizing the performance of the nozzle for various applications such as in rockets, turbines, and pumps.

2. What factors affect the pressure distribution in a nozzle?

The pressure distribution in a nozzle is affected by various factors such as the geometry of the nozzle, the fluid flow rate, the fluid properties, and the boundary conditions. These factors can significantly influence the performance of the nozzle and should be carefully considered during the calculation process.

3. How is the pressure distribution calculated in Abaqus?

In Abaqus, the pressure distribution in a nozzle can be calculated using the finite element method. This involves dividing the nozzle into smaller elements and solving the governing equations of fluid mechanics for each element. The pressure distribution can then be obtained by combining the solutions of all the elements.

4. What are some common challenges when calculating pressure distribution in a nozzle for Abaqus?

Some common challenges when calculating pressure distribution in a nozzle for Abaqus include accurately defining the geometry and boundary conditions, selecting appropriate element types and meshing, and ensuring convergence of the solution. It is also important to consider any assumptions or simplifications made during the calculation process and their potential impact on the results.

5. How can the results of pressure distribution in a nozzle be used?

The results of pressure distribution in a nozzle can be used to evaluate the performance of the nozzle and identify any areas of high or low pressure that may affect its functionality. This information can also be used to optimize the design of the nozzle and improve its efficiency. Additionally, the results can be compared to experimental data to validate the accuracy of the calculation method.

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