I just glanced at the top post but this is kinda silly. There is always motion, vibrational or resonant or linear. It's just a matter of degree. An engine is not a math construct.
True, but the motion of concern is the one that causes a friction issue between the rings and cyl wall. The atomic vibrations have little to nothing to do with that event. Heck, the rings still have momentum as the piston istelf does the 180 and continues on in that direction.I just glanced at the top post but this is kinda silly. There is always motion, vibrational or resonant or linear. It's just a matter of degree. An engine is not a math construct.
Yes, a time period is some time period, call it dwell or any other word if you like. What's the actual dwell time period the piston has paused it's motion? Math will tell us an exact #, but I can't seem to find what the # is, can you help find the actual time period? Is it "one millionth of a microsecond", or some other period?
And if the time period is that small does it make any diff whatsoever that the piston paused for that small time period? I would think the issue is only present when the pause is on same magnitude of, and bit longer than, the time it takes for the film layer to become useless (as explained by other people), so up front quick no-math analysis it seems the piston cannot stop for very very very small time period, otherwise the film layer would still be there and not be an issue.
The claim was and still is, as posted by others on bitog and the linked stuff by others, "the piston stops for a brief moment".You seem to like to change the terms and conditions of your statement as you go along and get incrementally disproven by those who clearly demonstrate more subject matter knowledge than you have to further obfuscate the issue to the masses or either confound/confuse yourself internally. ( not sure which at this moment)
Lets go basic- "technically" at this pass-through dimensionless nanosecond of yet-to-be-defined Planck time where said piston is at zero movement and potential, it would not require any lubrication at those points because there would be no actual friction.
Prior and post is a different story but waffle on, your torrential stream of word salad making endless contradictory assertations and refusing to acknowledge what has been told to you is a good field study of the end effects when Dunning Kruger and OCD collide at light speed.
I asked a very simple question, what's the actual dwell time where the piston or rings have paused their motion?
So then simplify it, the bearing clearances are filled with an incompressible frictionless liquid.Depends on the bearing clearance, I would think.
Depends on the bearing clearance, I would think.
What are the "many factors" that dictate how long the piston stops motion? And, with whatever factors you don't list here, for how long is the dwell time? It can all be describe using math, so can you list the math that has these many factors, and this math can also be used to calculate the dwell time near the BDC and TDC areas?Doesn't have anything to do with it really.
What does matter is the rod length, crankshaft rod journal length from the crank centerline, and engine speed.
It seems like Empire doesn't really understand how an engine actually physically functions. As the piston approaches TDC and/or BDC, the connecting rod is at an angle to the piston. In order for the piston to travel back the other way, the big end of the connecting rod must swing to the other side of the crank centerline. This is the point at which the piston is stationary at TDC or BDC. How long the piston is stationary is dependent on many factors.
They did already, something like 40deg centered on TDC and BDC. But that's not the question at-hand here.How about some of you guys with the math to do it estimate how the ring velocity change for each degree of crankshaft rotation effects lubrication needs?
The claim was and still is, as posted by others on bitog and the linked stuff by others, "the piston stops for a brief moment".
In reality the issue is between the rings and cyl wall, not the piston itself.
But ok, I will roll with whatever you say. So what's the dwell time the piston and/or rings have as they pause with no motion? Is it 2nsec, something smaller, something more than that. Math should be able to estimate that dwell time with some good accuracy (eg; the equation may not be 100% but the #'s would at least match that equation, etc).
I asked a very simple question, what's the actual dwell time where the piston or rings have paused their motion?
So then simplify it, the bearing clearances are filled with an incompressible frictionless liquid.
It's called simplifying on paper, for the purposes of simplifying. If the friction is a factor in the math and I remove it from the math, then it "magically" goes away, or in words, becomes no friction represented for that item.No such thing as a frictionless liquid and generally HD bearings have a minimum of 3 laminate layers of fluid flow generating heat ( just FYI)
They don't teach CFD in "nucular" engineering?
It's called simplifying on paper, for the purposes of simplifying. If the friction is a factor in the math and I remove it from the math, then it "magically" goes away, or in words, becomes no friction represented for that item.
It's an imaginary fluid, kinda like imaginary numbers that are used in math all the time. You know imaginary numbers, yes?
Ok, calling it quits here, most of you just don't get it, nor can you prove anything showing the math. Showing silly gifs of the motion proves nothing.
What are the "many factors" that dictate how long the piston stops motion? And, with whatever factors you don't list here, for how long is the dwell time? It can all be describe using math, so can you list the math that has these many factors, and this math can also be used to calculate the dwell time near the BDC and TDC areas?
Just looking for the dwell time that the piston stays stopped.
Doesn't have anything to do with it really.
What does matter is the rod length
If you pick any point on the velocity curve doesn't the piston spend the same amount of time at any arbitrary velocity? I'm confused as to why all the angst over the v=0 portions when apparently the entirety of the remainder is assumed to be correct.