by blaktopr » Mon Oct 27, 2008 12:10 am
Rick, I took a look for a few minutes and that swirl even happens on flat , concave chamber around the area of the exhaust valve/plug. This phenomenom I feel is the same as what is happening in an open bed of a pickup truck. There are many times I will have an empty plastic bag back there or something else kinda light. Driving at highway speeds only the item just rolls around in circles taking forever to fly away. The circular motion comes up from the tailgate to the cab and up the cab then to start again. I'm not really sure of the physics of it, but it might go something like this, plus I saw something on mythbusters testing the effects of milage and taneau covers, etc.
Airspeed is highest over the cab (over the plug protrusion), then slows once passed the cab over the bed getting some trapped by the tailgate (behind the plug, edge of exhaust at the margin). The increased speed of the air at that point before the plug drops out fuel, and dispeses it behind it. Pressure is now higher in the bed and the air wants to go to the low traveling to the cab and up the back of it (directly behind the plug, bring the fuel with it), just like the plastic bag.). The air re-enters the fast air and starts the process all over again, but the bag (fuel) is too heavy and too large a quantity to be entirely incorporated into the air, so it just drops back out again repeating the process. Thats my take on it.
If you can put a pitot tube in those areas, you may find the same results as if you were to probe at the back side of a restriction in a port. Look at what is done to also get fuel that dropped out back into the airstream. It's late and my mind is a little jumbled. I hope you got the gist of it. It's something we mess with in the port and see day to day in our life. I just don't know if it is a benefit to cooling the plug or a negative having a concentration of fuel not completely mixed, producing an uneven burn across the piston face. Chris.
Chris Sikorski