Did you get to measure the flow resistivity of the foam?
Maybe that could be simulated in the BEM
I do not have flow resistance measurements. It is extremely low however. This is air filter stuff - has to be low flow resistance. There is larger pore stuff which will be even lower. I started with about 50 PPI (instant failure,) then 40, then 30. 30-40 seems to be ideal in my application. Having lived with foam filled waveguides for some 15 years now and I would not be without it. Even "good" horns sound harsh to me otherwise.
When I see those impulses again, I am reminded to explain that the very early dual impulse spike at t=0 in the "difference" impulse, is the result of a 1/2 sample slowing of wavefront of one test over the other since the clock was synched between runs. Integrated over a sample and this spike will go away, Thus, if this spike is ignored then virtually all of the reduction comes from the tail.
When I see those impulses again, I am reminded to explain that the very early dual impulse spike at t=0 in the "difference" impulse, is the result of a 1/2 sample slowing of wavefront of one test over the other since the clock was synched between runs. Integrated over a sample and this spike will go away, Thus, if this spike is ignored then virtually all of the reduction comes from the tail.
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I'm still only not sure about the gyroid shape in particular. I'm curious about its effect. Overall, using a sparse infill as the holding support may be a good idea. I would only avoid the throat vicinity to minimize reflections - that's the reason I wanted to print the whole "tulip" from two parts with the supports in the middle.Could be worth a try printing a tullip with some light gyroid infill instead of supports
Maybe a line infill is good enough, I think one can randomize the start of it on each layer, so it's not a straight grid all the way...
Anything besides the horn that can be changed in the tullip I printed last that come to mind?
How did you come up with the ammount of "pinching" for the outer channels?
Maybe having a solid in the middle as most phase plugs do would help
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Greetings all,
over the weekend I measured several wave-guides and I have (i) curve y=f(z) for an axially-symmetric wave-guide and (ii) two orthogonal curves y=f1(z) and x=f2(z) for a rectangular wave-guide.
From the manual, chapter 2.1.3, the guiding curves are for (i) circles of differing diameters y, and for (ii) rectangles of differing dimensions x, y. However, based on the last paragraph, it is unclear, whether arbitrary shapes, and not only superellipse and superformula are implemented. Nevertheless, it would appear that I can approximate (i) by proper setting of a, b and m, n1, n2 and n3. and (ii) by proper setting of n > 2 and a, b.
Question 1: Is this correct, or is there an easier way that I am overlooking?
Chapter 4.1.1 defines the parameters for the horn geometry, but I have difficulty how to interpret/set them. Looking at demos 5 and 6, it appears that I cannot set the parameters a, b as a function of z. Based on the foregoing, one cannot use Ath to model arbitrary profile.
Question 2: Is the conclusion correct?
Question 3: Is there any trick how to achieve my goal?
Kindest regards,
M
over the weekend I measured several wave-guides and I have (i) curve y=f(z) for an axially-symmetric wave-guide and (ii) two orthogonal curves y=f1(z) and x=f2(z) for a rectangular wave-guide.
From the manual, chapter 2.1.3, the guiding curves are for (i) circles of differing diameters y, and for (ii) rectangles of differing dimensions x, y. However, based on the last paragraph, it is unclear, whether arbitrary shapes, and not only superellipse and superformula are implemented. Nevertheless, it would appear that I can approximate (i) by proper setting of a, b and m, n1, n2 and n3. and (ii) by proper setting of n > 2 and a, b.
Question 1: Is this correct, or is there an easier way that I am overlooking?
Chapter 4.1.1 defines the parameters for the horn geometry, but I have difficulty how to interpret/set them. Looking at demos 5 and 6, it appears that I cannot set the parameters a, b as a function of z. Based on the foregoing, one cannot use Ath to model arbitrary profile.
Question 2: Is the conclusion correct?
Question 3: Is there any trick how to achieve my goal?
Kindest regards,
M
If the goal is to simulate an existing device, then no, there's no directly supported way of doing it.
In an axisymmetric case it's possible to simply overwrite the node coordinates by your measured points in the file nodes.txt. Just set the number of length segments to your number of points and then overwrite the generated coords in the text file by your numbers.
In the general 3D case, there's really no way of doing it - nothing I could think of as feasible.
The whole ATH concept is based on the OSSE profile. There's no support for an arbitrary user-defined profile or function (yet).
In an axisymmetric case it's possible to simply overwrite the node coordinates by your measured points in the file nodes.txt. Just set the number of length segments to your number of points and then overwrite the generated coords in the text file by your numbers.
In the general 3D case, there's really no way of doing it - nothing I could think of as feasible.
The whole ATH concept is based on the OSSE profile. There's no support for an arbitrary user-defined profile or function (yet).
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BTW, I'm writing an application note on generating the spherical wave plugs. It will become just another feature of Ath - a natural extension of the currently implemented Source Definition Script as it already exists for a long time. Perhaps it will help to stimulate development. In theory it offers constant directivity and high loading at the same time - it's worth pursuing forward, IMO. The 5 vane/2" version I already showed will serve as a demo project.
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I do this quite often when I want to quickly try something - ABEC redraws the model immediately if you change something in the file, it's easy to get what you want by a simple cut-and-try approach (you may also need to touch the solving.txt to add/remove some nodes but more about that later) -
Attachments
2" driver/5-channel plug in Ath ("*.afp") format for Fusion 360, including the necessary Fusion script (AthProfileImport).
This time these are the raw vanes with zero thickness. This is left to be dealt with somehow, probably depending on the manufacturing technology used. Provided "as is", without any guarantee.
This time these are the raw vanes with zero thickness. This is left to be dealt with somehow, probably depending on the manufacturing technology used. Provided "as is", without any guarantee.
Attachments
I tried that and it didn't make any difference in the simulation, other than making the whole structure larger as a consequence. Hard to say what difference could it make in a non-ideal situation. It's definitely possible, I'll keep it in the software as an option.
Note that in the case of a regular CD phase plug there's an obvious reason for the solid center. I don't quite see a reason for it here.
That's great, and the import tool works perfectly. Is this designed for the same horn as in post #8742?
