Learning Forum

[lamiaa312]

Dear all ,

I have a question about modeling compressible flow through a  nozzle.

I have simulated the flow on sea level altitude and i had the expected results but now i need to study my flow at different altitudes ie  different atmospheric pressures and into vaccum too .I need your help  to set these operating conditions in fluent.

[Kalyan Goparaju]

Hello, 

The easiest way to approach the problem would be figure out the temperature, pressure and density values of the working fluid at the required altitude and provide them as the boundary conditions to the problem. 

Thanks, 

Kalyan

[lamiaa312]

hi thanks for ansewring ,

i have all these values but my problem is how to input my BC in the outlet and the same time the operating condition. for example, at sea level my pressure outlet should be 1atm  for ideal expansion and my operating condition is 1 atm too ...

[DrAmine]

Two choices either you set the operating pressure to your actual pressure level and adjust the gauge pressure at your opening or put the whole pressure level at your opening and provide zero as operating pressure. I generally put my pressure level as operating pressure even for high mach number. 

[mal3rashid]

let say......i am currently studying about the flow across high pressure turbine blades.....the only parameter that i have is the inlet total pressure and temperature.....thus i define the inlet boundary condition as pressure-inlet...but i am a little bit confused between total gauge pressure, supersonic pressure and operating condition pressure....so based on your explaination, should i just assigned total pressure at total gauge pressure and for supersonic pressure and operating condition pressure i set to zero?

[DrAmine]

Supersonic pressure is used only if your flow is supersonic at inlet or if you want to initialize from inlet.

[mal3rashid]

thankyou. One last question...right now, i will assigned total pressure at total gauge pressure inlet. operating pressure will be pressure at a level. and i also have pressure outlet and temperature at outlet boundary condition. When i insert operating condition and define magnitude of pressure and temperature outlet, my solution diverges/ float....can we define operating pressure and set pressure outlet at the same time?

 

[DrAmine]

Yes.