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#1 |
New Member
Saibal
Join Date: Feb 2017
Posts: 3
Rep Power: 9 ![]() |
Hello friends,
I am trying to simulate a subsonic diffuser by ANSYS 14.5 _ FLUENT. My Inlet mach number is 0.9 and Inlet gas is Air. I want to increase pressure at the outlet of a diffuser. So I have added a diverging area diffuser at the end of a pipe through which the flow is taking place. But in my result instead of rise in pressure and decreasing in velocity, reverse is taking place. Pressure is decreasing and velocity is increasing. Please help me out which boundary condition and solver I have to choose to obtain the exact result. Please give some suggestion about simulation of compressible flow in a diffuser. |
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#2 | |
Senior Member
Kushal Puri
Join Date: Nov 2013
Posts: 182
Rep Power: 13 ![]() |
Quote:
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#3 |
New Member
Saibal
Join Date: Feb 2017
Posts: 3
Rep Power: 9 ![]() |
Thank you for the reply.
I am completely describing my problem details: For the case of diffuser: Inlet Diameter-55 mm. Outlet diameter-110 mm. Inlet pressure- 410043 Pascal Inlet temperature-483 K. Inlet gas-Air Inlet Density-2.9563 kg/m3 Inlet velocity- 397 m/s. As the temperature at the inlet is 483K, Mach number at the inlet is 0.9, because the velocity of sound at inlet is around 440 m/s. During problem solving through Fluent, I have used P inlet as the inlet boundary condition.Gauge total pressure is 693400Pascal as I found it from isentropic table corresponding to M=0.9. Initial gauge pressure is 410043Pascal and Inlet temperature is 483K. For the outlet boundary condition, I have used P outlet as the boundary condition and the gauge pressure at outlet is 101325 Pascal. Operating condition pressure as 0 pascal. When I did not get the result, I changed the P outlet gauge pressure value to a higher pressure value than the Pinlet as I obtain that value from analytical calculation, but at that time also I found errors like reverse flow condition and divergence of the solution etc. In the solution method I used Implicit+AUSM second order upwind scheme. Please suggest me the appropriate procedure for solving a diverging diffuser. Thank You |
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#4 |
Member
MWRS
Join Date: Apr 2018
Location: Islamabad
Posts: 99
Rep Power: 8 ![]() |
Please help
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#5 |
Senior Member
Kushal Puri
Join Date: Nov 2013
Posts: 182
Rep Power: 13 ![]() |
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#6 | |
Member
MWRS
Join Date: Apr 2018
Location: Islamabad
Posts: 99
Rep Power: 8 ![]() |
Quote:
In terms of static pressure total pressure etc. |
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#7 |
Member
MWRS
Join Date: Apr 2018
Location: Islamabad
Posts: 99
Rep Power: 8 ![]() |
So I specify the theoretically evaluated static pressure at outlet or any certain value that is higher than inlet?
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#8 | |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,761
Rep Power: 66 ![]() ![]() ![]() |
At outlets: you need to specify the static pressure
Quote:
Code:
Gauge Total Pressure (pascal) Code:
Supersonic/initial Gauge Pressure (pascal) Almost all pressures in Fluent are gauge pressures, so that the letters Gauge appear everywhere for redundancy. |
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#9 | |
Member
MWRS
Join Date: Apr 2018
Location: Islamabad
Posts: 99
Rep Power: 8 ![]() |
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Tags |
ansys 14.5 fluent, compressible flow, subsonic flow in diffuser |
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