joe wrote:there may be ,but if there is it won't help explain why the higher velocity gasses between the piston head and the quench travel into the chamber .
If the area between the quench and the piston head is smaller , then the velocity of the gasses traveling out of it must be greater . Velocity and pressure are inversely realated .
The pressure in the squish region is higher (otherwise the chamber would evacuate itself into the squish!). The pressure in the chamber (which has a much larger volume, proven if you do the math) is lower. The pressure difference between them accelerates the mixture from the squish into the chamber. So the velocity is smaller in the squish region and increases as it reaches the squish-to-chamber fictional wall (via acceleration). It forms a planar jet. Pressure and velocity are inversely related in EACH control volume, not across both of them (squish, chamber).
Temperature is also involved , the temperature rises with the upward motion of the piston and is additive toward the velocity of the gasses generally .
Yes, I know. But thanks for that reminder.
SUPERsonic is what I said , and that means there's a ratchet involved , molecules get a one way ticket.
Supersonic means shock wave; it means travelling at a speed greater than the linear acoustic (infinitesimal) sound speed. Shock waves happen from explosions or objects travelling faster than the speed of sound (military aircraft). It doesn't happen in the chamber or squish unless you have detonation.
OH that's rich ! I'M THE SUPERIOR ONE ! Let's see .
what I learned in graduate school studying acoustics....
Superior? I don't know what that means. I'm probably more knowledgeable than most here in that field.
Try the library search here: http://web.mit.edu
Now lets cut thru the chatter I've given you a very good example of a very efficient working chamber , you point me at an empirical example which will undo the one I've mentioned, with your mans technology.
It's not my man's technology.
One person dismissed the concept with no physical or technical reason other than his own opinion. He still might be right in the dismissal, but I offered a reason why it MIGHT be a good idea as a counter-example, and then explained why. Using a level of science/engineering (sans math) that's probably appropriate for the mixed group here.
There are many examples of efficient combustion chambers, especially when you look at the development of them in the last 30 years. So it's not a stretch to think that someone might come up with another idea, to improve on what we have now.
As for your example: methanol has 26% greater flame speed than gasoline does, with a nitro mix it's even higher.... so in both cases less igntion advance is needed; boosted applications also
have faster burn speeds so less ignition advance is needed there as well. So there are several factors involved in your example, and they all reduce the need for ignition advance BASED ON FUEL CHOICE AND BASED ON BOOST, not necessarily because of the chamber efficiency.... so they serve only as an attempt to confuse this discussion, IMO.
The only chamber efficiency that would be worthwhile to discuss is a stock chamber vs a modified chamber (using the alteration that prompted this thread in the first place).
I'm not comparing engine A to engine B, but you seem to be.
Last edited by kdrolt on Wed Aug 17, 2005 11:18 am, edited 2 times in total.