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Problem with Injection in engine Cylinder

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Old   January 12, 2010, 11:37
Default Problem with Injection in engine Cylinder
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Hello,

I am trying to inject fuel into the engine cylinder. I have done some calculations and tried to input it into fluent but the simulation does not reveal correct results.

The problem is that even after changing the mass flow rate (Even by increasing it 10 times), the flow doesnt come fully inside the cylinder. It just comes upto a very short distance. I am injecting it with pressure of 200 bar so, the injection time should not be a problem. Can anyone also suggest which injection module (Like Single, surface.. etc) will be the correct one for this purpose

Any suggestions and help are highly welcomed

Thank you all in anticipation
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Old   January 12, 2010, 22:05
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Are you using DPM or multiphase? With 200 bar I assumed it's diesel.
Just to be sure.. have you properly scaled your grid?
Often I have encountered this problem just because I forgot to scale..
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Old   January 13, 2010, 01:58
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Agree with mas comment. it should be scale problem.

If its not, its better u ask question with picture and point out the parameter u put in.
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Old   January 13, 2010, 04:50
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Thanks for your replies.

Actually I am using Hydrogen and I am just trying species transport module. I am not using DPM and neither multiphase. There are no droplets and eve the phase is not changing.

I tried scaling the grid again but I am getting same results.
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Old   January 13, 2010, 07:19
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mayur,

i guess we are doing something similiar. I am injecting propane into engine chamber.
also no phase change but species transport.

check out on my post
Dynamic Mesh on Pintle type injector.

Again, picture please. make sure people understand on what u doing before u ask question.
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Old   January 14, 2010, 03:42
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Hi mayur and herntan,
I guess we are on the same boat, I'm injecting methane in an ICE chamber.
Species transport is the right way to go for this kind of case.
I hope we can help each other.
Mayur, please give more detail on your work.
Herntan, nice video. Have you managed to solve your fuel leak problem using layering technique?
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Old   January 14, 2010, 03:55
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Mas,

The only way to solve the leaking problem is stop injecting or deactivate the zone.
i still working on the pintle movement. Its very tough.
Mas, ur working on 4 stroke engine? how is the progress so far? any video u can share?
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Old   January 14, 2010, 06:00
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Yes, I'm working on 4-stroke engine. Specifically a wall-guided direct injection approach. I'm currently having difficulties in validating the calculated spray against schlieren images obtained from a constant-volume-chamber experiment, namely: spray angle too small, spray penetration too long, etc. Hence, no good video yet. I think it has something to do with species-air interaction or mixing, or maybe the std k-epsilon that I'm using, or maybe the surface roughness inside the nozzle, or other causes. Please share if you have any experience on any of these.

Regarding the fuel inlet boundary condition, is it good estimation to gradually increase and decrease the fuel flow imitating the needle/pintle lift without actually modeling its movement?
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Old   January 14, 2010, 21:09
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Yes. The reason i having the pintle moving cause i found that the pintle movement is not as fast as we think. The pintle actually spending around 50% of time in opening it to full stroke. so we only got 50% of injection time in full stroke. The effect of pintle slowly open should be great.
Do you have any picture of the injector u use? My prof actually plan to change the injector, maybe u got a good suggestion.

Wall guided injection... hmm.. i tried to do some, but it just make thing worst.
The fuel following the wall and keep stick to it and never come out and mix.

I haven't do any validation until now. I was wondering how is ur schlieren image validation done, can u share?
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