SpudFiles

I posted this simulation from youtube because I thought it might be of some help when building a piston valve and deciding whether to construction a D/2 or D/4 configuration. The flow in this sim is certainly not spectacular and it can be considered a "D/1" configuration. Now imagine how much more the flow will restrict if a piston is placed at a D/2 or D/4 position. I think the D/2- D/4 formulae are great for a quick, general rule but, they don't reveal the full truth.

[youtube][/youtube]

lol 'kolanko'....... nice to see some polish stuff here

actually I've been thinking today how cool would it be if there was a programme that can model how gases work... lol another strange coincidence (the previous one was that shoutbox idea)

Are you familiar with that programme ?? how well does it work ?

POLAND_SPUD wrote:Are you familiar with that programme ?? how well does it work ?

I'm very familiar with it........it's wonderful! It's included in newer versions of Solidworks. As you may recall, I suggested that you obtain a copy of Solidworks and use it rather than "sketch" programs.

yeah I am working towards that goal... I got autocad but switching from sketchup to the real thing is not as simple as I hoped it would be


what exactly can you do with it ? Can gas interact with other parts, for example in a way that you can model piloting of the QEV (how the piston moves back etc.) ?

well if you say you are pretty familiar with it you might as well model a few things for the community

plzzzzz

There are programs that model fluid flows. The field is called CFD, short for computational fluid dynamics.

The 10 second video you say posted probably took at least several hours of work to make. CFD is not an easy thing and it takes both experience in setting it up and a lot of engineering know-how to both setup the problem and interpret the results. I don't think most people here should bother with it for this reason.

Empirical tests to see what works and what does not work is always necessary. And here it's much more practical. Make a gun with a similar geometry to what you want to do and do some tests spanning a range of different openings to see how much is necessary.

I have considered using some CFD to find some steady state values for contraction coefficients, etc., but I never got around to it. As I've said, they'd have to be compared against reality. Sometimes the simulation is wrong. Plain and simple.

By the way, my planned BAGS 2.0 simulation should basically be 1D CFD. It won't product anything near as pretty as what 2D and 3D simulators do, but it'll be usable by most and reasonably fast.

For the price of a full retail version of solidworks, you could build 50 cannons.