So that's a .020" gap x .75" long x 2. Great job! Thanks for doing that!
Don't know why you keep bringing up a high efficiency bypass filter that's suppose to be used in conjunction with a full flow filter in discussions about filters with leaks. A filter with torm media or a significant leak path is not working like a bypass filter system, unless you consider it to be an inefficient "bypass" filter.
Close to the area I used in the flow/dP calculator.
Shouldn't be any "funneling" or "scooping". The leak gap path is just an opening area in a relatively large pressurized reservoir (the dome end of the can). It flows a volume dependant on the oil viscosity and dP across the gap area.
Ya, I re-read that after I read your post from 2 minutes before, & realized in a pressurized liquid system the only factor defining flow rate would be dP. I knew you'd catch that...
As I said, an accurate calculation would not be trivial. I don't have a good way to do it, at least in a reasonable amount of time. I merely pointed out that using an equivalent area round orifice overstates the flow, and probably more than just a little.
I was a bit surprised that it was .020”. Also the .75” length is conservative as I measured the gap straight across.
Here's a better configuration calculation - see results below. Using a rectangular opening actually flows MORE than a round orifice when both have the same flow area under the same conditions.
Not what this flow/dP calculator says. Both have the same flow area of 0.03 sq-in and the same flow path length of 0.125 inch. The rectangular slot will flow more oil of the same viscosity at the same dP. Both are in the laminar flow regime.
Here's the flow/dP calculation using two rectangular flow gaps as you reported (one of this size on each side of the leaf spring), each being 0.020 in by 0.75 inch in size, and assuming the flow path length is 0.125 inch for the flow to go from the dirty side to the clean side.
I get it better now, and it’s not only about oil filters. When I change filters later this year, put the new ones on I have already, after another year or so, maybe I can check back and see all the calculations and conclusions that people finalize. Then decide if I should buy the Fram Ultra. There are going to be a lot of posts by then. It should be all decided in a year or two. Or three, I think I have enough filters bought for that. Not throwing them away.Don't know why you keep bringing up a high efficiency bypass filter that's suppose to be used in conjunction with a full flow filter in discussions about filters with leaks. A filter with torm media or a significant leak path is not working like a bypass filter system, unless you consider it to be an inefficient "bypass" filter.
A full flow filter isn't suppose to be bypassing dirty oil all the time. Any oil that goes around the media can be "dirty", regardless of how many times it's circulated through the engine. And it's a continuous leak, not a short term infrequently bypass like when the bypass valve operates.
Since leaky filters, including torn media seems to be fine to use now, might as well just go back to the bypass only oil filtering system used in the 1940s.
I think the only thing that will change with a constriction is velocity.
OG on!!! I’m more comfortable now.
That’s Fantastic.
Are you gonna cut that one up & see if it's leaking?
Probably next weekend. I’ll also have my granddaughters vw in for an oil change and c&p.
Those two models aren't directly comparable, since the orifice model contains a large area reduction whereas the straight pipe model doesn't. If you set D1 to be just slightly higher than D2 in the orifice model, you'll get a more comparable estimate, and the result should be almost the same as if you were using the circular straight pipe model.
The flow field entering a constriction and exiting a constriction changes. For flow entering the constriction, the fluid accelerates. For flow exiting the constriction, the flow decelerates. This induces a pressure drop in addition to the pressure drop of flowing through the orifice itself. This additional pressure drop reduces the flow that will go through the constriction at any given total pressure drop available. That is my point. The calculation used above assumed a plain rectangular passageway for the rectangular slot, but used an orifice calculation for the round hole, which included the effects of the constriction and expansion. That is apples and oranges. You need to use the same methodology for both of them.
My point exactly. Better yet, use a round pipe for the round hole rather than an orifice with a slight constriction. The orifice calculation probably uses a discharge coefficient of around 0.62, which probably won't amount to a lot if you only have a small constriction, but it will still be there. Using straight pipe, that will not be a factor.
