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Fluent cyclone pressure drop

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Old   January 29, 2018, 14:46
Default Fluent cyclone pressure drop
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Hello friends.
https://www.youtube.com/watch?v=dalhTs4-0-c I am trying to calculate the pressure drop and cyclone efficiency with fluent cyclone analysis of the video. I use 1,200,000 hexa mesh in ICEM CFD. Turbulence model RSM model, I use Pressure Velocity Coupling-SIMPLE, Pressure-PRESTO, Momentum-QUICK and Second Order Upwind. I start with the steady solver to drive the flow, and then I use transiet. I calculate the pressure loss too much compared to the experimental data. I could not figure out where I was wrong. I will have some questions .

1 - How is total and static pressure loss calculated ? a or b

-a) Surface integral - mass weighted average, Total pressure drop = inlet total pressure - outlet total pressure
-b) volume integral mass average, total pressure loss = Total Pressure is Fluid

2 - When the input speed is 12.69m / s, the fluent output speed is calculated more. Since the output area is larger than the input area, the output speed must be smaller than the input speed. Where can the problem?

3 - Compared to the Fluent surface integral, the static pressure loss accounts for more than the total pressure loss. Can someone explain this to me.

Please help me .
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Old   February 2, 2018, 12:38
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I have read the cfd-online forum from start to finish. But I could not find the answers to the questions I asked. can somebody please help me?
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Old   February 2, 2018, 14:30
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Quote:
Originally Posted by mkal View Post
Hello friends.
https://www.youtube.com/watch?v=dalhTs4-0-c I am trying to calculate the pressure drop and cyclone efficiency with fluent cyclone analysis of the video. I use 1,200,000 hexa mesh in ICEM CFD. Turbulence model RSM model, I use Pressure Velocity Coupling-SIMPLE, Pressure-PRESTO, Momentum-QUICK and Second Order Upwind. I start with the steady solver to drive the flow, and then I use transiet. I calculate the pressure loss too much compared to the experimental data. I could not figure out where I was wrong. I will have some questions .

1 - How is total and static pressure loss calculated ? a or b

-a) Surface integral - mass weighted average, Total pressure drop = inlet total pressure - outlet total pressure
-b) volume integral mass average, total pressure loss = Total Pressure is Fluid

2 - When the input speed is 12.69m / s, the fluent output speed is calculated more. Since the output area is larger than the input area, the output speed must be smaller than the input speed. Where can the problem?

3 - Compared to the Fluent surface integral, the static pressure loss accounts for more than the total pressure loss. Can someone explain this to me.

Please help me .
I suggest you to use k-e RNG with modification in viscosity (if I remember correctly) , and 2nd order not QUICK for equations. Steady solutions can be used for cyclone, why transient that brings some hardships?
For question 1, a is correct. Also you can refer to literature for that
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Old   February 2, 2018, 15:28
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Thank you for your reply. Transient convergence is easier. I am using speed input and static pressure output boundary conditions. Why is the static pressure drop greater than the total pressure drop? why is the output speed larger when the output area is larger? CFX gives the same results. How do calculate Fluent or CFX pressure ? How should I interpret the results? Any advice on this will be appreciated.
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Old   February 5, 2018, 13:05
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Friends found the source of the incorrect results. Fluent saw the scale in cm. Now the results are of reasonable value. But the fluent output speed and the dynamic pressure again calculate incorrectly. How should I calculate the total pressure drop? should I calculate the outlet dynamic pressure value by ignoring the value that Fluent calculated? The output speed and the dynamic pressure CFX are also calculated incorrectly. I have not found a cause. Please give me a little tip.
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