CFD/CAD/Thread

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hoffman900
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Re: CFD/CAD/Thread

Post by hoffman900 »

One of the personal challenges in this work it to stay in a seeker mindset, forget that you "know" anything.
This is definitely something one man or small operations have and why engineering teams like to bring in fresh talent.

There are lots of talented people on here, but I also think they’re looking at this like it’s a port at 28” of water on a flowbench and are constraining themselves.

Jon, am I seeing a lot more tumble than swirl here? Hard to tell with that view.
-Bob
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Re: CFD/CAD/Thread

Post by SpeierRacingHeads »

hoffman900 wrote: Thu May 18, 2023 10:31 pm
One of the personal challenges in this work it to stay in a seeker mindset, forget that you "know" anything.
This is definitely something one man or small operations have and why engineering teams like to bring in fresh talent.

There are lots of talented people on here, but I also think they’re looking at this like it’s a port at 28” of water on a flowbench and are constraining themselves.

Jon, am I seeing a lot more tumble than swirl here? Hard to tell with that view.
If it means anything I did the port, like all of them, at 50"..
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Re: CFD/CAD/Thread

Post by SchmidtMotorWorks »

hoffman900 wrote: Thu May 18, 2023 10:31 pm Jon, am I seeing a lot more tumble than swirl here? Hard to tell with that view.
You are correct, it is the view, it always looks like that when you look at a zero thickness section perpendicular to the section.

Here is the full set of arrows.
swirl.png
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Re: CFD/CAD/Thread

Post by SchmidtMotorWorks »

SpeierRacingHeads wrote: Thu May 18, 2023 10:35 pm If it means anything I did the port, like all of them, at 50"..
I will make another setup more like a flow bench so we can compare.
What depressions shall I do? 28 and 50?
I don't think many people here have a 50" bench.
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Re: CFD/CAD/Thread

Post by SchmidtMotorWorks »

SpeierRacingHeads wrote: Thu May 18, 2023 10:24 pm What about making the roof line straight. Not sure why it has that dip in it.
Something like this?
Take the high arch out or make a change to it?
roofline.png
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Re: CFD/CAD/Thread

Post by GARY C »

SchmidtMotorWorks wrote: Thu May 18, 2023 11:45 pm
SpeierRacingHeads wrote: Thu May 18, 2023 10:35 pm If it means anything I did the port, like all of them, at 50"..
I will make another setup more like a flow bench so we can compare.
What depressions shall I do? 28 and 50?
I don't think many people here have a 50" bench.
Would the difference between the 2 be noticeable?
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Re: CFD/CAD/Thread

Post by hoffman900 »

SpeierRacingHeads wrote: Thu May 18, 2023 10:35 pm
hoffman900 wrote: Thu May 18, 2023 10:31 pm
One of the personal challenges in this work it to stay in a seeker mindset, forget that you "know" anything.
This is definitely something one man or small operations have and why engineering teams like to bring in fresh talent.

There are lots of talented people on here, but I also think they’re looking at this like it’s a port at 28” of water on a flowbench and are constraining themselves.

Jon, am I seeing a lot more tumble than swirl here? Hard to tell with that view.
If it means anything I did the port, like all of them, at 50"..
I think that’s great. Everyone should.
-Bob
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Re: CFD/CAD/Thread

Post by hoffman900 »

SchmidtMotorWorks wrote: Thu May 18, 2023 11:42 pm
hoffman900 wrote: Thu May 18, 2023 10:31 pm Jon, am I seeing a lot more tumble than swirl here? Hard to tell with that view.
You are correct, it is the view, it always looks like that when you look at a zero thickness section perpendicular to the section.

Here is the full set of arrows.

swirl.png
Yep, there it is. Thanks! Will have to chew on this.

Will be interesting to keep track of the swirl and tumble as you guys make changes.

Still also curious on the different runners with their varying bend / lengths effects on the ports, but I’ll let you guys have at it.
-Bob
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Re: CFD/CAD/Thread

Post by BLSTIC »

What would filling the roof approximately like this achieve?
fillroof.jpg
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Re: CFD/CAD/Thread

Post by JC565Ford »

SchmidtMotorWorks wrote: Thu May 18, 2023 11:51 pm
Something like this?
Take the high arch out or make a change to it?

roofline.png
It might like the floor to have a bit of a dip before the crest of the short side. Sometimes the line of sight on the floor is not the best thing.

Image

Image
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Re: CFD/CAD/Thread

Post by fordified »

SchmidtMotorWorks wrote: Thu May 18, 2023 10:11 pm Here is the peak of the floor arch raised.
Unfortunately it made things worse, at least the way it is now, there are sill possibilities to lay the short side back if that is interesting to see.

Here is how I raised the arch, could have done it lot's of different shapes, maybe less maybe move the peak?
There is always an element of surprise in this stuff.
One of the personal challenges in this work it to stay in a seeker mindset, forget that you "know" anything.
compare 1-2 raise floor.png

Here is port 2 again
Intake Port 2 Long Section Velocity.png

Compared to port 3 (raised arch)
Intake Port 3 Long Section Velocity.png

Here is vorticity in port 2 again
Intake Port 2 Long Section Vorticity.png

Here is where trouble shows up in vorticity past the peak.
Intake Port 3 Long Section Vorticity.png

Here is piston top pressure from port 2
Intake Port 2 Piston Top Pressure.png

Here is piston port pressure from port 3, the same piston velocity pulls more vacuum
Intake Port 3 Piston Top Pressure.png

Here is velocity with arrows of a slice, this image shows the difference between how air follows a piston than it would flowing into a bottomless cylinder. Since the piston is much larger than the curtain area, the air is traveling much faster than the piston as it leaves the curtain.
It decelerates very fast and then turns very fast to follow the piston top.
Notice how biased the recirculation is on the valve face.

Section Following Piston.png
This is a perfect learning example of how upstream changes affect downstream event. The reverse can occur too of course.

You've achieved a better velocity gradient which is a good thing and will likely produce a quieter port but as you pointed out the vorticity has increase in the bowl. I think you'd both agree that the area right before the throat/seat on the short side is the biggest concern.

Does your program take into account back angles on the valve? If so, can you change the width on them? Turbulence is also occurring around the valve stem. It would be interesting to see if widening and/or raising the teardrop at different points around the guide has a positive effect.

How much area did you lose with this change? Did you increase area elsewhere to compensate?

I would like to see what occurs at different lift points especially where peak CFM demand occurs and higher.
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Re: CFD/CAD/Thread

Post by SpeierRacingHeads »

SchmidtMotorWorks wrote: Thu May 18, 2023 11:45 pm
SpeierRacingHeads wrote: Thu May 18, 2023 10:35 pm If it means anything I did the port, like all of them, at 50"..
I will make another setup more like a flow bench so we can compare.
What depressions shall I do? 28 and 50?
I don't think many people here have a 50" bench.
Yes please do 28 and 50.
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Re: CFD/CAD/Thread

Post by SpeierRacingHeads »

SchmidtMotorWorks wrote: Thu May 18, 2023 11:51 pm
SpeierRacingHeads wrote: Thu May 18, 2023 10:24 pm What about making the roof line straight. Not sure why it has that dip in it.
Something like this?
Take the high arch out or make a change to it?

roofline.png
yes, I wonder with and without the floor change?
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Re: CFD/CAD/Thread

Post by SchmidtMotorWorks »

fordified wrote: Fri May 19, 2023 9:02 am This is a perfect learning example of how upstream changes affect downstream event. The reverse can occur too of course.

You've achieved a better velocity gradient which is a good thing and will likely produce a quieter port but as you pointed out the vorticity has increase in the bowl. I think you'd both agree that the area right before the throat/seat on the short side is the biggest concern.

Does your program take into account back angles on the valve? If so, can you change the width on them? Turbulence is also occurring around the valve stem. It would be interesting to see if widening and/or raising the teardrop at different points around the guide has a positive effect.

How much area did you lose with this change? Did you increase area elsewhere to compensate?

I would like to see what occurs at different lift points especially where peak CFM demand occurs and higher.
Generally, I do things in a sequence of coarse to fine.
The coarse things are big moves like setting pinch area and other major upstream areas.
Then move on to the finer details like valve job with a finer mesh.

Presently, we have increased the port volume with the pinch widening so we need to make a change that will bring the volume back within the rules.

We need to plan tests strategically, I work @ minimum 12 hour days at my aircraft job and designing another head too, so I have time to do one test a day on this.
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Re: CFD/CAD/Thread

Post by SchmidtMotorWorks »

JC565Ford wrote: Fri May 19, 2023 12:40 am It might like the floor to have a bit of a dip before the crest of the short side. Sometimes the line of sight on the floor is not the best thing.
Can you use an image editor to draw some curves to explain what you mean?
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