The "Cascade" - mini-cup directed jet-impingement block design (56K warn)

[LiquidRulez]

Originally posted by jaydee116
Well I don't know about that. The poly piece is pretty much all strait cuts except for the O ring groove and the outer channel. A hand mill should be able to do it with someone that knows how to use it. But I doubt a dermal would work. Maybe if you used the router attachment and precisely positioned a jig on each cut. Would be a bitch without a mill though.

I could make that block on my little CNC mill. It loves plastics. I got a few new ideas of variations of this block I am going to try in the future. Got some other things in the works now though....

Man ...you must be a F'in pro with a manual mill if you think you could mill that jet tubes in the shape of small stop signs on the bottom and remain within tolerance on EACH and every one!

I know you can make it on a fairly accurate CNC........but not everyone has the luxury that few of us have in that arena.

Personally I dont think that the elongated tubes really make one bit of difference....Id just make a solid center plate with the chamfered holes.But maybe Cathar has come to a diferent conclusion that ultimately lead to cutting the tubes that way to begin with....IMO......having the overall waterchamber after water exits from the cups, closer to the base would prove to be a good thing, versus the extra volume of it as it is now....just totally bypass the cut extrude around each jet tube

[Cathar]

The reason for the elongated tubes are these:

1) The height of the jet stream above where it strikes is actually important. At present I have it a little too high, even with the tubes. Am fixing that.

2) The tubes are there to stop the flow from other cups interfering with the jet streams.

Now the first prototype I made without the jet tubes was about 25% more dense than the tubed version, yet the tubed version just pips it. The next step is to get the tubes even smaller and increase the density to match that of the first revision, better balance the jet heights, and balance the base-plate thickness from CPU to bottom of the holes, and work on getting the cup shape tweaked.

All of these things will be addressed in the next step, and it's going to be some pretty intricate stuff that will make the current jet-tube plate look almost clunky in comparison.

[jaydee]

Originally posted by LiquidRulez
Man ...you must be a F'in pro with a manual mill if you think you could mill that jet tubes in the shape of small stop signs on the bottom and remain within tolerance on EACH and every one!

I know you can make it on a fairly accurate CNC........but not everyone has the luxury that few of us have in that arena.

Personally I dont think that the elongated tubes really make one bit of difference....Id just make a solid center plate with the chamfered holes.But maybe Cathar has come to a diferent conclusion that ultimately lead to cutting the tubes that way to begin with....IMO......having the overall waterchamber after water exits from the cups, closer to the base would prove to be a good thing, versus the extra volume of it as it is now....just totally bypass the cut extrude around each jet tube

I certainly agree it would take a person that knows his manual mill to make those cuts decent, but they are all strait cuts providing you can move the peice around and they don't really need to be perfect tolerance, as long as the holes don't get cut into it should be ok. I know I don't have the skill to do it with my hand wheels on my mill, but I do know there are people that can do it. I am certainly glad I have the CNC package and don;t have to worry about it though.

[chewyboy]

cathar,
you are insane!

BTW keep up the great work

[Rayman2k2]

Originally posted by chewyboy
cathar,
you are insane!

BTW keep up the great work

that's one thing to call a genius

[ozzy7750]

i dont see that it should be that hard to do on a manual mill, by my counting it would require 26 passes, all straight lines. you would want to only do about 5 passes per day though i rekon, otherwise you would start to rush it and not align everything perfectly. i dont have a small enough mill bit though, the smallest i have now is a 3mm, prob need a 1.5 or something.

it could be simplified a lot by making it a grid array of jets rather than honeycomb, but i think that the honey comb will allow the water to flow away much easier without impeding the other jets.

but cathar has said that his 'final' version will have more densly spaced holes - requires even more passes. i think i would be willing to experiment with something like the size of his current one.

[Cathar]

Minor updates on progress.

Have had the opportunity to tweak jet height, various levels of jet tube submersing into each cup and cup geometry.

Have managed to knock a clear 1C off what I was achieving before. I've hacked at the base-plate using sub-standard tools to try this stuff and I believe that there is more to offer if it is all machined properly.

In any event, this even further confirms the directions I need to take. The machinists haven't had the time to do the design shrink yet, and this gives me the opportunity to apply an extra tweak to the design as submitted last week.

Overall, the design is coming along very well with very encouraging results. I am extremely eager to get the next revision in hand. I have a very good feeling that it's going to offer something special from a performance perspective. Jet straws will be 3/64" in width each with 1/32" separating each one. Going to be some fine-detail machining....

[Tuff]

Nice to see the small stuff arriving...wish the machinists good luck for me

Tuff

[jaydee]

Originally posted by Cathar
Minor updates on progress.

Have had the opportunity to tweak jet height, various levels of jet tube submersing into each cup and cup geometry.

Have managed to knock a clear 1C off what I was achieving before. I've hacked at the base-plate using sub-standard tools to try this stuff and I believe that there is more to offer if it is all machined properly.

In any event, this even further confirms the directions I need to take. The machinists haven't had the time to do the design shrink yet, and this gives me the opportunity to apply an extra tweak to the design as submitted last week.

Overall, the design is coming along very well with very encouraging results. I am extremely eager to get the next revision in hand. I have a very good feeling that it's going to offer something special from a performance perspective. Jet straws will be 3/64" in width each with 1/32" separating each one. Going to be some fine-detail machining....

I am impressed with getting the straws in the holes. I think your on the right track and am impressed with your accomplishments on this so far. Keep up the great work! And keep us informed!

[MadDogMe]

Yep!, getting those jets down into the cups is quite a feat considering the size/tolerances you're working with. Are you still going with the machined polytop or are you planning on using tubes 'inserted' into the top? ( I was thinking of using sections of a large syringe, a vetanary one maybe?, one with a 0.5~1mm bore)...

[hara]

And glueing them to the top you mean?

Is this what you're trying to acheive cathar? Tubes inserted into the cups?

[Cathar]

Originally posted by hara
Is this what you're trying to acheive cathar? Tubes inserted into the cups?

I wouldn't say trying, it's what is actually there today. The tubes aren't terribly deep into the cups - just enough to stop the outflow from other cups being a disturbance, but being careful to keep the jets at the optimal height away from the cup base.

Are you still going with the machined polytop or are you planning on using tubes 'inserted' into the top?

Will still be using a one-piece machined top (well middle plate actually).

[JCYC5]

Cathar, is it possible to achieve something like your middle block with acrylic?

[hara]

OOps sorry, hard to judge the height of the tubes from the pics.

[Cathar]

Originally posted by hara
OOps sorry, hard to judge the height of the tubes from the pics.

No need to be sorry. The picture plate has been machined. The outer sections on the bottom were skimmed off and the O-ring channel cut deeper. What you see pictured is before that took place.

[Cathar]

Originally posted by JCYC5
Cathar, is it possible to achieve something like your middle block with acrylic?

Sure, you could use anything really. The middle plate isn't a load bearing structure, it just needs to be easily machinable and behave well to being machined.

[ataxy]

bravo!

[jaydee]

Originally posted by JCYC5
Cathar, is it possible to achieve something like your middle block with acrylic?

Acrylic mills pretty good actually. Just have to find the right feed rate and rpm to keep it from chipping.

This is just plain cheap acrylic:



Like a hot knife through butter, just make sure the endmills or tooling is sharp.

[Al Kaseltzer]

First of all, the jet array looks Fantastic, definitely the next step in WB technology.

But I just don't get the cups.

I read through all of BB2K's thread that Cathar gave credit to as an influence, and it seems the primary influence on the cups or dimples idea is ease of manufacture, all you need is a drill press.

Now I realize every design needs to take into account manufacturing complexity and manufacturing costs, but considering the reputation Cathar's Machinists have for breaking new ground, the simplicity of the cups just seems to me like a letdown.

I do have to concede that the results Cathar has reported are impressive, and whatever works, works. Maybe I don't like the cups, just because they're too unconventional. (Unlike the Whitewater, which was the first WB I'd ever seen that looked like it had any real thought in the design, based on the success of fins for cooling dating back to the dawn of the industrial age)

It seems to me the ideal thing to put under those jets would be an array of Pin Fins. Take for example, a comparison between a baseplate with cups, and the exact negative of that - replace every cup with a pin of equal length and diameter. You would have the exact same surface area, and the exact same impingement effect on the baseplate and on the base of the pins.

I was just about to say you would have more area of thin Base Plate between the pins than you would at the bottom of cups - but have just realized that would depend on the dimension & density of your pins/cups. It would be true for the geometry of the BP you posted - It just looks like there's too much copper to me.


Hmmm, that realization has kind of killed my focus - As I consider different geometries, I'm no longer quite so doubtful of the cups. Instead, I can see the potential of the fins formed by the material between the cups.

Oh well, so much for doubting Cathar - now I'm just looking forward to the results of the different prototypes.

[ozzy7750]

i cant remember if it was on this forum, or the ocau forum, but cather explained why he used the cups. it was something like this:

the water jets hits the bottom of the cup, impingement surface number one. it then is VERY turbulent as the water comes out of the cup, impingement surface number 2 on the side of the cup.

but as you say, there does seem to be a lot of copper in that bvase plate, but cather has said that he is working on another one, he said that the new ones jets will make the old one look 'chunky'

as with you, very much looking foward to the next set of results

[Cathar]

The cups are there to "manage" the water-flow, more than they are there to increase surface area, however I think that you will find that the cups offer more surface area where it counts over a pin design.

Jet arrays have been around for quite a while but only ever applied to flat or dimpled bases, but never completely "cupped". One of the biggest issues with getting them to realise their full potential are down to two things:

1) Adjacent jets interfering with each other - after the immediate impingement action the impingement "circles" clash into a turblent region that is basically doing nothing much at all as only a minute part of that turbulence is coming into contact with the base. Due to the clashing of these regions, this also serves to diminish the radius of the primary jet impingement region under the jet. The only real solution is to widen the separation between the jets to allow the impingement region for each jet to develop properly, but this then carries the drawback that as you move further away from the central impingement area the cooling effect of the jet is diminished. This is what jaydee116 was experiencing with his first multiple jet block.

2) All the "stale" water has to go somewhere. This typical means taking it past the path of other surrounding jets, interfering with their power and disrupting their direction, which creates extra boundary layers because the impingement regions don't form properly.

"Cupping" with the tubes partially inserted into each cups solves these problems. It allows a "private" area for each jet to form properly. The jet forms the primary impingement area. The cups width is such that the walls are positioned just outside of the main stagnation region of the jet. This is where the flow pattern is at its "thinnest" and just where the boundary layer starts to form outside of the primary stagnation region. Here the thin high velocity water flow strikes the cup walls. The water as this stage is travelling at close to the same velocity as at the jet nozzle. So we now get a "secondary" impingement effect that occurs as a ring around the base of the cup wall. This, couples with the main jet region, concentrates two highly efficient impingement zones both at the cup base and within 1mm of the cup base walls. It's important to note that the cup width is rather critical for this to all balance properly. Too wide and the water from the primary jet starts to slow down, and boundary layers start to form before the cup wall. Too narrow and the pimary stagnation zone cannot form properly, loses power, and instead of achieving a full effective impingement, results in more of a super-turbulent mash of flow, which while still effective at cooling, is not as efficient.

The cup height is dictated more by the optimal jet height, rather than anything else. The insertion of the jet tubes into the cups helps to establish a flow path out of the cup to provide less interference with the incoming jet stream, and the insertion also protects the jets from the collective outwashes of nearby jets as the outwash flows towards the outlet(s).

From initial appearance, the apparant drudgery of a few holes drilled into the copper plate seems very mundane, but only until it is understood what their exact purpose is, and that the actual height, depth and width of each cup represents a very exacting balance in conjunction with the jet tubes to ensure a maximising of the efficiency of the impingement principles used.

The separation of the cups is also important. We want enough copper to both maintain structural integrity when used with extremely thin base-plates (substantially less than 1mm), while also offering just enough copper to conduct the heat up the cup walls far enough to take full advantage of the secondary impingement effect on the cup walls.

The whole point of the design is that a vast majority of the heat is soaked up within 1mm from the CPU core, or even less. The White Water did the same within about 2mm of the CPU core on average when the fins are taken into account.

The cupped design allows for the simultaneous mix of ultra thin base-plates, high native structural integrity, and the ability to dissipate the heat even closer to the CPU than even the White Water could manage. IMO, it's about as close to direct die cooling as you can get, but gives you about twice the effective surface area to trade off against the thermal interface layer penalty. It would take about a sustained 80000 W/m^2K thermal transfer region applied to a direct die cooling scenario to exceed what the cupped/jetted design can offer even after taking into account the TIM layer, and I have trouble seeing how that high value could be achieved, not to mention the inherent dangers with direct-die cooling itself.

[satanicoo]

how about having a pinin the middle of the cups?

[bigben2k]

Hummm... no.

The jet would be forced around the pin, reducing the inpingement effect. It's the same problem as with my Radius.

It would also be quite difficult to manufacture.

[jaydee]

Had some play time on the laser today. This was one of my tests today to see what I could do with it. Middle peice took 3mins 30seconds. But it doesn't leave as nice a finish as a endmill. I also did one with twice as many holes at half the size of these and it worked great untill I tried to laser cut the holes. The pipies melted.... So that just tells me I will have to just drill the holes out instead.

It is a little over 1/8" deep into the acrylic.



-----------
I thought I was doing something different on this untill I looked at Cathars. He did the same damn thing. Only thing I could think of to get the water to go to the holes.

[cristoff]

what about this?