Reference Pressure CFX
I am doing flutter analysis of AGARD 445.6 wing. all physics has been developed and I am sure that all settings are correct. the only problem that I am getting is setting the pressure. I have a reference pressure in default domain>basic settings and a reference pressure in air as ideal gas so what these pressure signifies? which pressure is used to find density. for density we use absolute pressure which is sum of reference and static pressure? from where I will get static pressure? lets sum up. I want to have a dynamic pressure of 4500 Pascals at .9 Mach using air as ideal gas so what pressures and temp should I use? Kindly reply this is very Important:confused: |
Density is calculated on absolute pressure. The absolute pressure is the sum of the reference pressure (the one on the domain tab) and the pressure variable (which is static pressure).
Please do not hijack multiple threads with the same post again. It is a misuse of the forum. I have removed all the duplicate posts. |
Reference Pressure CFX
I will not post same message to multiple threads, I just did it to get an reply from immediately.
thanks ghorrock for the help but my question remain unanswerd I need dynamic pressure of 4500 pa at Mach .9???? I used air as ideal gas and its reference pressure is 1atm not the one at basic settings tab. reference temp is 298k. assuming that velocity at .9Mach is 270m/s or any value you would suggest? SO what reference Pressure now I should use at default domain>basic setting? to get dynamic pressure of 4500 pascals at velocity of 270m/s. Thanks in Advance for replies.. |
Your initial question was vague.
A dynamic pressure of 4.5kPa where? At the inlet? At a specific point in the domain? Isn't this simply a matter of setting the inlet velocity to a appropriate value to get the correct dynamic pressure? Set the reference pressure to be the ambient pressure, so atmospheric (if in the atmosphere) or the wind tunnel down stream pressure (if a wind tunnel). |
Reference Pressure
Thanks ghorrocks for reply. a dynamic pressure of 4.5kpa at wing or for simplification make it at inlet. Velocity I thought as well to just change it to match the dynamic pressure but I have to at Mach .9 as well, so the relation v=M*sqrt(gamma*R*T) must all to be specified.
Now can you suggest some velocity at inlet and some reference pressure? I am stuck and very few days are left to pressent this work. |
As I said, the reference pressure should be set to the atmospheric pressure.
It sounds like your condition of Ma=0.9 and dyn pressure of 4.5kPa can be evaluated to define the velocity, density, pressure and temperature of the inlet boundary. Then I would use a simple inlet boundary with velocity and temperature defined and an outlet at 0 pressure. |
thats what I cant understand that how the dynamic pressure and Mach can be translated to inlet velocity,temp etc.????? can you tell how can I find inlet velocity from these conditions
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That is just basic fluid mechanics from the definitions of Mach number and dynamic pressure, and anything else you already know about the flow.
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Hi solomedic,
Did you find a way to change the dynamic pressure for your analysis. I am currently doing the same AGARD 445-6 analysis (ANSYS 14) and am struck at the same place. I have used the data from the literature for velocity, dynamic pressure and input them at the default domain setting for reference pressure and velocity value for inlet velocity, but I am not able to get the flutter characteristics as found in the experimental result. If you have solved the problem can you please guide me on how you achieved it. Regards ACD |
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you can contact me on muhammadaamir38@yahoo.com, hope I will be able to help you better |
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I also do the agard 445.6 wing flutter analysis but get stuck wth setting the reference pressure, density and velocity in CFX. Could you tell me how to do that? |
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