valve motion 0,045-0,238 mm lift

valve motion 0,045-0,238 mm lift

Computational fluid dynamics (CFD) simulation of a valve lift event. Simulating air flow around the valve (and valve seat).

Results given as pressure contours.

Category:

Science & Technology

Tags:

• valve
• motion
• engine
• CFD

[AaAsCd]

what the hell?

[alpha754293]

@AaAsCd It ought to be quite self-explanatory, but I'll explain anyways:

It's a CFD valve motion analysis/simulation showing I think it's static pressure contours. The point of the study was to actually get the mesh around the valve moving and not necessarily the results themselves, but the changes in pressure was my method of verifying that it's working properly.

[alpha754293]

@AaAsCd Typically when you have tetras both on TOP and BOTTOM, the probability of you running into negative volume elements is VERY high because the 4th point in a 3D tetra can be "squeeze" through the planar bottom triangle. And with compressing the elements on both sides of the valve -> leads to a very BAD mesh/math condition.

[vegaquarker]

yep... maybe a better sofware could help :P

[alpha754293]

@vegaquarker The software isn't the issue. The underlying mathematics is. But you can't really change the underlying math/phsyics. Well...you CAN, but the results would be absolutely worthless and meaningless.

I typically use strictly 3D codes. They're MUCH harder, but they're also MUCH more accurate because it can capture the geometries better. (If you have two intake values and 1 exhaust value, that other video you sent won't work.)

[alpha754293]

@vegaquarker The model I'm running is the ACTUAL engine data from a MY05 S197 4.6L V8. It was a BITCH having to stitch and close all those surfaces up in CATIA because there were so many super tiny gaps (on the order of 1e-5 mm); so I spent like...a few weeks hunting them down and closing them off one by one.

[alpha754293]

@vegaquarker 2-D. I have one too: watch?v=T1tiaARMEGc

I'll be impressed if they can spin that and make it into 3D and still get it to work just as well/easily.

[vegaquarker]

@alpha754293 btw! take a look at this... looks good :P

watch?v=mcJWK0N6i-o&NR=1

[alpha754293]

@ballsniff13 See description.

[alpha754293]

@vegaquarker It's actually very slow if you look at it really closely. The valve doesn't move very much. The changes in contour is because I used relative contours rather than absolute (global), because if I had used global, you wouldn't be able to see the very tiny changes in pressure. ICE valve CFD is a bitch. You have to mesh with tetras cuz of geometry, but tetras are stiff, and prone to negative volume (super bad). Unless you artifically relax (dampen) it (sim/mesh).