Valveless pulsejet-computational fluid dynamics

Moderator: Mike Everman

Re: Valveless pulsejet-computational fluid dynamics

Postby ganuganu » Fri Apr 28, 2017 5:38 pm

Mike Everman wrote:Oh, that one is fun to watch! I would love to see the pressure animation as well. Does it not make sense that the velocity scale should be -300 to +300m/sec? Loses that "hot-cold" spectrum, but freezing it would allow some better interpretation.

Will surely post the pressure plots in my next simulation. -300m/s i dont think so, the velocity reduces to about 0.06m/s near outlet, i took this as ref and setup the velocity limits in scene plot.
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Re: Valveless pulsejet-computational fluid dynamics

Postby Mike Everman » Fri Apr 28, 2017 5:46 pm

The velocity has a direction vector left and right. Maybe a silly thing I'm wondering, as we see the propagation of the velocity changes, which does indicate a change in direction.
I'm trying to wrap my mind around whether I can be fooled by interpreting the propagation of the velocity change with gas movement direction. I mean, is it possible that a gas movement could be going opposite to the visual movement of the colors?
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Re: Valveless pulsejet-computational fluid dynamics

Postby ganuganu » Fri Apr 28, 2017 6:27 pm

Actually there will be a velocity motion in opposite direction during suction phase from exhaust and intake side but velocity does not show in negative value (i.e positive velocity in reverse direction). In this video the motion of colours represents the movement of mass either in froward or reverse direction.
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Re: Valveless pulsejet-computational fluid dynamics

Postby ganuganu » Sun Apr 30, 2017 6:17 am

Another valveless type numerical simulation but this time its single intake chinese type. Its really interesting to see the things happening inside the PJ.

https://youtu.be/FgFmT-_KZfA
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2017-04-30 11_47_16-New notification.jpg
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Re: Valveless pulsejet-computational fluid dynamics

Postby ganuganu » Thu May 11, 2017 2:21 pm

A just for fun simulation.

Video link:
https://youtu.be/AlN7lFJ826o
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2017-05-11 19_50_36-New notification.jpg
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Re: Valveless pulsejet-computational fluid dynamics

Postby Mike Everman » Thu May 11, 2017 2:47 pm

Ha! Nice. Oh yeah, I need to dig up jet dimensions for you!
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Re: Valveless pulsejet-computational fluid dynamics

Postby ganuganu » Mon May 15, 2017 1:46 pm

Another just for fun numerical simulation. This was fun creating.
https://youtu.be/VdnT-rudMb8
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Re: Valveless pulsejet-computational fluid dynamics

Postby Mike Everman » Wed Jun 21, 2017 1:35 am

Ha, nice. Sure does seem that the intake and exhaust alternate. I truly think that u-bent motors benefit from this effect.
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Re: Valveless pulsejet-computational fluid dynamics

Postby Mark » Wed Jun 21, 2017 2:44 pm

I didn't see any ear muffs on that stick figurine. The other day reading some Lockwood type literature, it said the sharp/torturous 180 u-bends lose a bit more thrust than the more gradual 180 bends. My snorkelers don't like u-bends but they will tolerate them, they're more fragile.
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Re: Valveless pulsejet-computational fluid dynamics

Postby ganuganu » Mon Jul 03, 2017 6:09 pm

Hi all,

Recently I have been thinking to write a CFD code specifically to simulate pulsejet engines. I started the work two weeks ago and now I have reached a starting point with fully compressible coupled Navier Stokes equation (2D and 3D analysis). Currently tweaking some of the things to match our requirements, I will release the GUI soon in public so that people can use for their research work.

This code can be run using either MATLAB or Octave.

Some images attached with this message.
Attachments
v1000.jpg
Lid driven cavity
pressure.jpg
Flow past rectangle
bacward_step.jpg
Backward facing step
flow _pipe.jpg
Flow through pipe
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Re: Valveless pulsejet-computational fluid dynamics

Postby Mike Everman » Tue Aug 29, 2017 4:42 am

Hey Ganesh, how is the project going?
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Re: Valveless pulsejet-computational fluid dynamics

Postby ganuganu » Sat Sep 02, 2017 10:58 am

Mike Everman wrote:Hey Ganesh, how is the project going?

Hi Mike

Got some updates, In my previous post you can see some colourful images it seems the Lax-Friedrich scheme is too dissipative. So now I have changed the scheme to Maccormack scheme (predictor-Corrector method), the results seems to be reasonable. I have uploaded aa video here of Flow past cylinder case for coarse grid,

https://www.youtube.com/watch?v=h2tYoRe_ByI

The above video is a fully compressible NS laminar regime.

Recent code: Compressible URANS(Unsteady Reynolds averaged Navier Stokes) equations with K-Omega (Wilcox model) turbulence model. Explicit method seems to diverge so currently trying to implement Algebraic multigrid method (Iteratve method). Regarding the combustion model I am going for Non premixed turb combustion (Once AMG is implemented next is combustion).

Regards
Ganesh
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Re: Valveless pulsejet-computational fluid dynamics

Postby Mike Everman » Sat Sep 02, 2017 7:01 pm

Great!
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