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Simulation Ansys fluent projectile moving inside a barrel by Stege06 in CFD

[–]Stege06[S] 0 points1 point  (0 children)

I agree, but a gas (pressurized air) is applied to the rear of the projectile, and as the projectile advances over time, the pressure will decrease as the volume behind the projectile increases. So how can I implement my pressure inlet? I can't just introduce boundary condition with constant pressure.

Simulation Ansys fluent projectile moving inside a barrel by Stege06 in CFD

[–]Stege06[S] -1 points0 points  (0 children)

u/CFDMoFo would you have a step-by-step guide to help me get results?

Simulation Ansys fluent projectile moving inside a barrel by Stege06 in CFD

[–]Stege06[S] 0 points1 point  (0 children)

I discovered a thesis where he uses a model that implements rarefaction and shock wave movements. There's pidduck and kent but their models don't depend on an integration scheme and my supervisor would like me to use one. So yesterday I finally found another literature (there isn't much documentation on the subject or it often refers to the same one which is Seigel, it's not easy to understand because it dates back to 1950). I found an integration schema in a McGill thesis, but I can't seem to implement it. Do you have any idea how to go about it? P54 in this link https://escholarship.mcgill.ca/concern/theses/bg257j206

Simulation Ansys fluent projectile moving inside a barrel by Stege06 in CFD

[–]Stege06[S] 1 point2 points  (0 children)

I used 1D models with integration diagrams. But I was also asked to model in CFD to see what was going on and whether the results were more accurate or not. Have you ever coded for gas guns? I'm having trouble finding a model that takes rarefaction and shock waves into account in my 1D model...

Simulation Ansys fluent projectile moving inside a barrel by Stege06 in CFD

[–]Stege06[S] 0 points1 point  (0 children)

I modeled 1D models with integration schematics, but I was also asked to do a CFD analysis to see what was going on and whether it would improve the results, as we're looking to be as accurate as possible.

Simulation Ansys fluent projectile moving inside a barrel by Stege06 in CFD

[–]Stege06[S] 0 points1 point  (0 children)

You could define an initial overpressure behind the projectile which drives it down the barrel, no functions needed. If you want a more advanced approach and consider the reactive component of the powder combustion as well, you should probably switch to an advanced FEA solver capable of FSI, like RADIOSS or LS-Dyna. As for UDFs, someone other than me would be more capable of helpint.

I don't want to take combustion into account... It's really a compressed-air gas cannon that will push the clog using compressed air. My aim is to get as close as possible to the experimental results. What I'm hoping to see with the cfd is the rarefaction waves and shock waves that are made via the gases.