How to define the opearating pressure and static pressure?

shanheplus · April 29, 2020, 05:22

The physical model looks like this. The inlet pressure measured by the experiment bench is 0.307MPa. And, the outlet pressure is 0.30MPa.(Both are total pressure).

The inlet volume friction is 1(liquid). And outlet is 0.3( liquid and vapor mixture).
The inlet mass flow rate is 0.0023 kg/s.
The tempature is 273.8221 K.

If I want to use FLUENT/ mixture model to simulate the physical phenomenon Which boundary condition should I use? How to define the oprating pressure and inlet

INLET
------
MASS-FLOW-INLET
inlet-liquid is 0.0023 kg/s and tempature is 273.8221K.
However, there should define the intial gague perssure. How to define it?

OUTLET
------
Pressure-Oulet
outlet gague pressure is? and what infomation of reverse flow should be define?

LuckyTran · April 29, 2020, 05:40

You can ignore the initial gauge pressure, it's not a boundary condition.

You might need to figure out how to convert your 0.30 MPa total pressure into a static pressure. If you were simulating air I'd tell you to use an isentropic relation. I have no idea what your physical model is but yeah, figure it out. If you were the experimenter, I'd seriously wonder why you didn't measure the static pressure in the first place.

But given that you have the total pressure at the inlet and a mass flow (how did you even get a mass flow?)... You can use a pressure inlet and pressure outlet with targeted mass flow rate option at the outlet. Hopefully we dont have any issues with static vs total temperature...

Take your best guess for what the reverse flow might look like. I like to guess the properties of the stuff arriving at the outlet. And by guess, I really do mean guess. Either way, if there isn't any reverse flow, then it won't matter. Since you/someone already did the experiment, you should already know whether or not there will be any reverse flow.

April 29, 2020, 05:22	How to define the opearating pressure and static pressure?	#1
shanheplus New Member SHAN He Join Date: Apr 2020 Posts: 17 Rep Power: 6	The physical model looks like this. The inlet pressure measured by the experiment bench is 0.307MPa. And, the outlet pressure is 0.30MPa.(Both are total pressure). The inlet volume friction is 1(liquid). And outlet is 0.3( liquid and vapor mixture). The inlet mass flow rate is 0.0023 kg/s. The tempature is 273.8221 K. If I want to use FLUENT/ mixture model to simulate the physical phenomenon Which boundary condition should I use? How to define the oprating pressure and inlet INLET ------ MASS-FLOW-INLET inlet-liquid is 0.0023 kg/s and tempature is 273.8221K. However, there should define the intial gague perssure. How to define it? OUTLET ------ Pressure-Oulet outlet gague pressure is? and what infomation of reverse flow should be define?

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April 29, 2020, 05:40		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	You can ignore the initial gauge pressure, it's not a boundary condition. You might need to figure out how to convert your 0.30 MPa total pressure into a static pressure. If you were simulating air I'd tell you to use an isentropic relation. I have no idea what your physical model is but yeah, figure it out. If you were the experimenter, I'd seriously wonder why you didn't measure the static pressure in the first place. But given that you have the total pressure at the inlet and a mass flow (how did you even get a mass flow?)... You can use a pressure inlet and pressure outlet with targeted mass flow rate option at the outlet. Hopefully we dont have any issues with static vs total temperature... Take your best guess for what the reverse flow might look like. I like to guess the properties of the stuff arriving at the outlet. And by guess, I really do mean guess. Either way, if there isn't any reverse flow, then it won't matter. Since you/someone already did the experiment, you should already know whether or not there will be any reverse flow.