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HGDT 0.5 online

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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HGDT 0.5 online

Unread postAuthor: D_Hall » Sun May 25, 2008 7:25 pm

All new combustion model.

Improved heat transfer model.

Unfortuantely, new file format as well so it won't just load any previous files you may have made (that's the price for playing with betas!).
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Unread postAuthor: Larda » Sun May 25, 2008 8:53 pm

One thing that i noticed is that you cant use a comma , you have to use a point when you enter the numbers.

What do you think of adding a ignition calculator, where you enter the electrode gap and it takes the pressure and number of gaps to calculate the voltage needed?
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Unread postAuthor: D_Hall » Sun May 25, 2008 9:11 pm

Larda wrote:One thing that i noticed is that you cant use a comma , you have to use a point when you enter the numbers.

Blame Visual Basic. That's not something I've gotten my fingers messy with. Well, OK, in the past I tried to, but I think I did more harm than good so I've backed off and let VB handle all the parsing.

What do you think of adding a ignition calculator, where you enter the electrode gap and it takes the pressure and number of gaps to calculate the voltage needed?

Dunno. Never really thought about it before.
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Unread postAuthor: Larda » Sun May 25, 2008 9:25 pm

D_Hall wrote:Blame Visual Basic. That's not something I've gotten my fingers messy with. Well, OK, in the past I tried to, but I think I did more harm than good so I've backed off and let VB handle all the parsing.


Ok, then maybe you should change so the program doesn't use comma when you chose (cm) instead of (in).

If you want to add the ignition calculator here is the calculation:
Code: Select all
V = 4.3 + 136 × (p / T) + 324 × (p / T) × Dg

# V = voltage potential (kV)
# p = absolute pressure in Bar
# T = gas temperature (Kelvin)
# Dg = electrode gap in mm
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Unread postAuthor: D_Hall » Sun May 25, 2008 9:37 pm

Larda wrote:Ok, then maybe you should change so the program doesn't use comma when you chose (cm) instead of (in).

Huh?

Is it changing? If so, I have absolutely ZERO idea what is going on. I've NEVER tried to change such things midstream.

If you want to add the ignition calculator here is the calculation:
Code: Select all
V = 4.3 + 136 × (p / T) + 324 × (p / T) × Dg

# V = voltage potential (kV)
# p = absolute pressure in Bar
# T = gas temperature (Kelvin)
# Dg = electrode gap in mm

Got an arc energy result in there somewhere? I mean, the arc will HAVE to have a certain energy density to result in ignition. If it's gonna be done, it might as well be done right.
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Unread postAuthor: Larda » Sun May 25, 2008 10:02 pm

Huh?

Is it changing? If so, I have absolutely ZERO idea what is going on. I've NEVER tried to change such things midstream.

Here is a few screenshots.
The first is when i start the program, then i change it all to metric , after that i can remove all the decimals without affecting the result.

Got an arc energy result in there somewhere? I mean, the arc will HAVE to have a certain energy density to result in ignition. If it's gonna be done, it might as well be done right.


I found some numbers here, locks like the minimum ignition energy for propane/air is 0,26mj

http://yarchive.net/chem/ignition_energy.html

Edit: I haven't found how the energy needed for ignition is affected by the pressure yet.
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HGDT0.5-1.PNG
HGDT at startup.
HGDT0.5-1.PNG (32.16 KiB) Viewed 1160 times
HGDT0.5-2.PNG
Configurations.
HGDT0.5-2.PNG (7.64 KiB) Viewed 1160 times
HGDT0.5-3.PNG
In metric.
HGDT0.5-3.PNG (32.21 KiB) Viewed 1160 times
HGDT0.5-4.PNG
In metric with the decimals removed.
HGDT0.5-4.PNG (31.67 KiB) Viewed 1160 times
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Unread postAuthor: D_Hall » Sun May 25, 2008 10:33 pm

OK, based on the progression of screen shots it looks like....

1) Since you live overseas, you've got your computer set up to do the whole comma thing (where we use periods).
2) In some initialization stuff I assign some text values to some blocks. Those values are being inserted with periods (ie, as text, just the way I specified).
3) VB tries to deal with commas, but since there are some periods showing up... Well, perhaps some things are getting screwed up.

So what I've done: I just went in and reassigned some of those text blocks as numerical inputs. There's some type conversions and such... In any event, I've compiled a new version and uploaded it to the site. NOT in the .zip file, mind you. JUST in the "updated executable" location.

Can you give it a whirl and see what it does?
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Unread postAuthor: Larda » Sun May 25, 2008 10:47 pm

Doesn't work at all. :(
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Unread postAuthor: D_Hall » Sun May 25, 2008 11:01 pm

WTF?

For it not to have made any difference, I could have seen that. But to cause a crash? I'm totally confused.
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Unread postAuthor: D_Hall » Sun May 25, 2008 11:06 pm

OK, another version uploaded to the executable location.

Give it a whirl?
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Unread postAuthor: Larda » Sun May 25, 2008 11:15 pm

Same problem now.
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Unread postAuthor: D_Hall » Sun May 25, 2008 11:34 pm

Where are you?

More to the point: What are the region settings on your computer?



edit: OK, for some reason I had imagined you in Sweden and set my region settings to that. Guess what? I can reproduce the error! Woohoo!
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Unread postAuthor: Larda » Sun May 25, 2008 11:47 pm

Yes, i'am from Sweden. :lol:
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Unread postAuthor: D_Hall » Mon May 26, 2008 12:01 am

Good news: I know what the problem is.

Bad news: I'm not sure how to fix it without potentially causing other problems.

What's happening... Visual Basic is screwing up. When it sees "0,05" it stops at the comma. It just sees the leading 0. Result? Division by 0.
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Unread postAuthor: starman » Mon May 26, 2008 12:29 am

D_Hall wrote:Good news: I know what the problem is.

Bad news: I'm not sure how to fix it without potentially causing other problems.

What's happening... Visual Basic is screwing up. When it sees "0,05" it stops at the comma. It just sees the leading 0. Result? Division by 0.


Isn't there a way to make VB recognize and use the regional settings within Windows for its decimal style? I would think so, but if not, you may have to just do some string checking in the fields for commas before the calculation and accommodate from there.

Edit: Sorry, looks like you are all over the regional settings thing.
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