Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by GARY C »

My understanding is that is is a calibration used by every one for comparisons sake just like measuring a cam at .050 so that their is a stnd used by everyone.

ARP uses the same tq calibration standards that snap on uses for it's tq wrench but does that mean that 50 lbs of tq is actually 50 lbs? All that really matters is that the standard calibration is the same.

If you started making 2x4's actually 2" x 4" you could never build a house using industry standard blue prints.
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by Erland Cox »

vannik wrote: Thu Mar 22, 2018 1:06 am A few things to keep in mind:

1. Laminar boundary layer and flow needs steady flow over a minimum distance to develop, this can be achieved on a flow bench but never in an engine, the flow is way too unsteady and short for that except maybe on the exhaust side far from the head,

2. A turbulent boundary layer is what we should aim for, it adheres to turns better and is thinner than a laminar one, Erland's first picture shows it quite nicely, it also allows more flow in a pipe,

3. The requirement to test a port with a turbulent boundary layer is one of the reasons why it is important to test at higher pressure ratios as working a port with the wrong boundary layer can give misleading results.

Whatever pressure drop you do your testing at you will still be far into turbulent flow.

https://www.uio.no/studier/emner/matnat ... _intro.pdf

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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by maxracesoftware »

Erland Cox wrote: Wed Mar 21, 2018 7:21 pm Bob, that is not what happens.
Texturing the surface activates the boundary layer and keeps it thinner longer so that the air can follow the surface.
If the boundary layer goes upp in thickness it greates a wake and as the pressure is higher where flow is slower
that wake can be pushed against the flow and cause separation.

Image

Image

Erland
anyone mention "Mixture Flow or Wet Flow" in this Thread ?

what happens if you have Wet Mixture Flow impacting a dimpled -vs- smooth Golf Ball ?
or in the case of Intake Ports ... what happens if you have a wet Mixture , such as , using M100 Methanol,
with mirror finish Intake Ports / Chambers -vs- rough-edged Golf Ball dimpled Burr finish Int Ports / Chambers

you do not Race with just Air ( no Fuel ) inside an intake Port, like you Flowtest .

can a rough-edge dimple Burr Golf Ball effect be better than a smooth-dimple Golf ball effect
would not a edged dimple mechanically breakup some portion of sliding Fuel into better Mixture quality delivered to the Cylinder ?
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by groberts101 »

I understand most of what you guys are saying here. But.. maybe there some misinterpretations or slight loss in translation/specific application occurring between in-compressible solid mass fluids flowing through straight pipe and the compressible gaseous mixtures we squash twist and shear around corners? Obviously there are many varying percentages of laminar airflow within the port and we can only discuss tiny, and sometimes indistinguishable for some ports?, changes created with differing port surface finishes.

Hopefully it's ok to cite that publication. I'll remove it if necessary, Erland.
zero, e.g., . The magnitude of u9 is usually just a few percent of u–, but
the high frequencies of eddies (in the order of a thousand per second) makes
them very effective for the transport of momentum, thermal energy, and mass.
In time-averaged stationary turbulent flow, the average values of properties
(indicated by an overbar) are independent of time. The chaotic fluctuations of
fluid particles play a dominant role in pressure drop, and these random
motions must be considered in analyses together with the average velocity.
Perhaps the first thought that comes to mind is to determine the shear
stress in an analogous manner to laminar flow from t 5 2m du–/dr, where
u–(r) is the average velocity profile for turbulent flow. But the experimental
studies show that this is not the case, and the shear stress is much larger due
to the turbulent fluctuations. Therefore, it is convenient to think of the turbulent
shear stress as consisting of two parts: the laminar component, which
accounts for the friction between layers in the flow direction (expressed as
tlam
5 2m du–/dr), and the turbulent component, which accounts for the
friction between the fluctuating fluid particles and the fluid body (denoted
as tturb and is related to the fluctuation components of velocity). Then the
total shear stress in turbulent flow can be expressed as
(8–36)
The typical average velocity profile and relative magnitudes of laminar and
turbulent components of shear stress for turbulent flow in a pipe are given in
Fig. 8–21. Note that although the velocity profile is approximately parabolic
in laminar flow, it becomes flatter or “fuller” in turbulent flow, with a sharp
drop near the pipe wall. The fullness increases with the Reynolds number,
and the velocity profile becomes more nearly uniform, lending support to the
commonly utilized uniform velocity profile approximation for fully developed
turbulent pipe flow. Keep in mind, however, that the flow speed at the
wall of a stationary pipe is always zero (no-slip condition).
Here's another I like because it solidifies some of my understanding on the subject.
Turbulent flow is characterized by random and rapid fluctuations of
swirling regions of fluid, called eddies, throughout the flow. These fluctuations
provide an additional mechanism for momentum and energy transfer.
In laminar flow, fluid particles flow in an orderly manner along pathlines,
and momentum and energy are transferred across streamlines by molecular
diffusion. In turbulent flow, the swirling eddies transport mass, momentum,
and energy to other regions of flow much more rapidly than molecular diffusion,
greatly enhancing mass, momentum, and heat transfer. As a result,
turbulent flow is associated with much higher values of friction, heat transfer,
and mass transfer coefficients (Fig. 8–19).
Even when the average flow is steady, the eddy motion in turbulent flow
causes significant fluctuations in the values of velocity, temperature, pressure,
and even density (in compressible flow).
So, again. Tiny ball bearings created by way of the chatter finishes inherent ability to reduce frictional net mass movement losses due to creation of thicker boundary layers. And this comes in spite of the fact that there is actually greater friction created between the fluids/gasses and no slip zone. Maybe this "stickier area" helps to turn and break up the wet flow around the short side?

Furthermore, that boundary layer, due to it's partially compressible(remember that the port walls are NOT completely and fully fuel wetted 100% of the time with the very largest fuel droplets) can bunch and gather up in certain areas(both liquid AND air) moreso than other areas. Obviously fluid displaces some of the air and changes things up. Seems pretty obvious what happened when the airflow is at least partially unbalanced exiting the SSR curtian area. I have absolutely no experience with wet flow testing but my guess is it may show even greater depth of reaction from varying wall textures. Which then causes larger gradients of turbulent vs laminar mass flow throughout the entire port. Nothing about the flow in a bent pipe is completely linear, or at least little of it aside from the central core flow areas in straighter sections where the pitot can be easily placed for measurment. lay it flat up against the wall and the readings will be falsified by the very tool used to measure it. Probably need a needle sized pitot to even get that close without displacing the very area that you're trying to measure. Using a pitot inside an overly choked port or terribly shaped SSR apex is an exaggeration of that affect.

In the end, what we are talking about here may be outside of the pitot's resolution and capability due to it's required size and placement alone. Cut big honking grooves and chop half of them out and the boundary layer will get fatter than santa clause so you can clearly measure it. Too bad frictional increases easily kill away any potential gains from greater laminar airflow %. Cut them down to the size of a chattered burr finish and may not be as easily recognized. I also still believe that with the pressures and velocities associated with peak mass movement within a "wet port".. inside a running breathing engine.. there are certainly areas and occasions where that boundary layer is highly variable. Thicker and thinner.. compressed and pulled upon.. and could potentially be "tuned" to aid other areas that are struggling to pull their weight within the cross section.

To carry that even further, and as quoted in the above excerpt, the small displacement area created by larger eddies causes the now larger % of thicker boundary areas mass displacement to be realigned into another area of the port. Which basically makes the cylinder think the port has slightly decreased in size as the mass is now moving faster FPS over a broader section of the ports cross section. Picks up the dead zones and makes them work harder to pull their weight within the cross section. Then as the cross sections flow requirement increases.. the boundary layer gets squashed/compressed just enough to make the cylinder think the port is just a tad larger then it was before that peak airflow requirement. I think we are far and well into the hair splitting category here. Sorry it got so long Erland, or anyone else who has enough time to read, I was multitasking and the reply kept growing! #-o

EDIT: I see Larry responded in regards to wet flow while my novel was being written!
Last edited by groberts101 on Thu Mar 22, 2018 4:10 pm, edited 4 times in total.
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by CGT »

cspeier wrote: Thu Mar 22, 2018 1:47 pm I had this big long post typed up
Yeah I saw it.
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by user-9274568 »

CGT wrote: Thu Mar 22, 2018 4:02 pm
cspeier wrote: Thu Mar 22, 2018 1:47 pm I had this big long post typed up
Yeah I saw it.
Actually you didn't. I never clicked post. I did delete the original post because it wasn't worth it. He can call everyone in the country and that does this for a living wrong if he wants. No worries.
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by statsystems »

cspeier wrote: Thu Mar 22, 2018 4:07 pm
CGT wrote: Thu Mar 22, 2018 4:02 pm
cspeier wrote: Thu Mar 22, 2018 1:47 pm I had this big long post typed up
Yeah I saw it.
Actually you didn't. I never clicked post. I did delete the original post because it wasn't worth it. He can call everyone in the country and that does this for a living wrong if he wants. No worries.


Well damn. I would have liked to read it.
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by groberts101 »

cspeier wrote: Thu Mar 22, 2018 4:07 pm
CGT wrote: Thu Mar 22, 2018 4:02 pm
cspeier wrote: Thu Mar 22, 2018 1:47 pm I had this big long post typed up
Yeah I saw it.
Actually you didn't. I never clicked post. I did delete the original post because it wasn't worth it. He can call everyone in the country and that does this for a living wrong if he wants. No worries.
I may not be half as smart or experienced as many of you guys are.. but I'm sure as hell old enough to know there is far more involved to label everything as either black or white! TONS of grey area's.

I also find it interesting that your tests show that burr finishes may not work in every single port design, shape and size. That alone should give some people enough pause to wonder if there may be more to it. :D
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by statsystems »

groberts101 wrote: Thu Mar 22, 2018 4:16 pm
cspeier wrote: Thu Mar 22, 2018 4:07 pm
CGT wrote: Thu Mar 22, 2018 4:02 pm
Yeah I saw it.
Actually you didn't. I never clicked post. I did delete the original post because it wasn't worth it. He can call everyone in the country and that does this for a living wrong if he wants. No worries.
I may not be half as smart or experienced as many of you guys are.. but I'm sure as hell old enough to know there is far more involved to label everything as either black or white! TONS of grey area's.

I also find it interesting that your tests show that burr finishes may not work in every single port design, shape and size. That alone should give some people enough pause to wonder if there may be more to it. :D

I've said it before but it's probably worth repeating when it comes to port finish.

If I could achieve burr finish results like Larry, Chad and what Charlie are getting I'd damn sure try it more. I can't duplicate that. Not even close. So I do what I do that gets the results I want.

IMO, it takes a damn lot of practice and experience to get the finish the way these guys do.
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by Rick360 »

cspeier wrote: Thu Mar 22, 2018 1:48 pm Your doing it right! Just like everyone in this country. Just like Harold Bettis will tell you to do it.
Just keep following the herd.

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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by Erland Cox »

There is no laminar flow whatsoever in any engine or flow bench.
All flow there is fully developed turbulent flow.
Activating the boundary layer stops it from growing so it makes the boundary layer thinner.
Slowing the air ingreases pressure and thickens the boundaary layer.
Speeding up the air decreases pressure and thins the boundary layer.
Aor hates slowing down and going up in pressure.
Air hates to turn.
So never slow down and turn the air at the same time.
Air is not like a car on a race track.

Erland
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by user-9274568 »

Rick360 wrote: Thu Mar 22, 2018 4:51 pm
cspeier wrote: Thu Mar 22, 2018 1:48 pm Your doing it right! Just like everyone in this country. Just like Harold Bettis will tell you to do it.
Just keep following the herd.

Rick
LMFAO

So, does RON'S calibrate their bench like you do?
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by RevTheory »

Don't take the bait, Chad. That guy will argue with a fence post.
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by user-9274568 »

RevTheory wrote: Thu Mar 22, 2018 5:14 pm Don't take the bait, Chad. That guy will argue with a fence post.
That is a fact. But he needs to answer my question....
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Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

Post by Erland Cox »

How do you calibrate your bench Chad?
I have used sharp edged plates for mine but I have seen different flow results from benches calibrated with the same plates.
And usong them on top of a Superflow 600 did not work at all.

Erland
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