"Radius" by BigBen2k

[myv65]

Originally posted by utabintarbo
And given the fact that a solid top was deemed to be most appropriate, your point is...?

Bob

His point is that the top may not be required for structural purposes. What's described is the method for calculating a moment of inertia, which largely determines bending "strength". While the relationships are correct, they only apply to a solid member. In short, a fin crossing the base doesn't make it 40X stronger. It's a little more involved than that.

In summary, you must first determine the neutral axis, which will correspond to the center of gravity. Since the fin is "thin" compared to the width of the base, the neutral axis will be very close to the center of the base. Then you calculate each member's area moment relative to its own center (this is the 1/12*base*height^3 portion). Finally, you add the member's area multiplied by its distance from the neutral axis^2. This is the composite area moment. It's basic strength of materials stuff, but pretty much greek if you haven't studied it before. The Roark book I mentioned earlier goes into just a tad more detail and tabulates copious loading conditions for plates, beams, cylinders, etc., etc.

[MadDogMe]

:shrug:Mistook

[pippin88]

Originally posted by utabintarbo
Ben,

If you recall, I posted my idea of what your block would look like in the "Ultimate block? Theory" thread. Since then I've come up with a few ideas, which I will post, if you like. A couple of q's come to mind:
1. Have you given up the idea of the fins at the bottom imparting a "swirl"? ie. curved vs. straight radial fins.
2. Are you wedded to the idea of a uniform thickness baseplate? Recall that Cathar's fins brace the baseplate against the cover, effectively giving him a stiffer bp to compensate for his lack of thickness. Also, his has a higher density of "finnage" than yours will at a given point, I believe. Refer to my posts in the "Ultimate waterblock" for the direction I am heading.

As to Cathar's block, I believe he said that he had the fins EDM'd into the copper. When I talked to one of my co-workers about machining 1mm channels into copper, he wasn't particularly enthusiastic. PITA!

I also have an idea or two re: mounting. If you prefer, I can contact you off-line, but that might be considered bad form. In any case, any help I might be able to give re: CAD and NC Programming is available.

Bob

Sorry if this has been said, but the fins are milled, none of it is EDM

[utabintarbo]

Originally posted by myv65
His point is that the top may not be required for structural purposes.

Agreed. But since it was decided to go copper top, I thought it would be easier to machine with the center-post configuration. In that context, his point is informative yet not totally relevant. If Ben wants to go Lexan top, things could be different...

Bob

[bigben2k]

All right, before everyone gets all huffy and puffy, I'll clarify:

As of now, a copper top is my preferred direction, because I'm not able to resolve the resulting structural integrity: it's out of my league. I have noted however that the resulting strength would be cubed if the crosshairs are not chopped up.

As you all know, the fins are part of the structure of the block i.e. they are what prevents the 2 mm baseplate from caving in. This is done in 2 ways:
1-having solid fins, which by torque only help keep the baseplate flat
2-Having a solid top, where the fins rest up against it.

The load applied comes from the clamping pressure, which would be in the 20 lbs range.


That being said, a clear top would be nice. I believe that the polycarbonate would be best.

What I don't know is what kind of stress points either configuration (copper top, poly top, solid fins/chopped fins)creates, but it is clear that there would be some pressure applied against the top.

I also don't know what kind of deflection I can expect from any load applied against a copper bar.


What also concerns me a great deal is the clamping mechanism. As per AMD specs, the clamping pressure should be applied longitudinaly over the core. I believe that preferably, the clamping force should be applied centrally, but this design makes this near impossible.

What we have so far is this:

Note: there would be a spring effect from this copper extension, and I don't know how to calculate this either. I do need those numbers, in order to select the proper clamping pressure.

[bigben2k]

Originally posted by unregistered
Ben
invest in a calculator, and get some practice using it
and make dwgs to scale, may help you to 'see' what's going on

to compress an o-ring 30%, what is being done ?
- it's cross-sectional diameter, relative to the longitudinal axis, is being reduced by 30% (or 40 if you prefer)
[this will tend to slightly increase it's diameter, Roark describes the deformation calcs]
- is it's volume being affected ? nooo
[not at the stress levels involved]
- so if the o-ring's volume was 70% of the groove's (or 60 if you prefer), has it changed ? nooo

so what then is the cross-sectional area of a 1/16" o-ring ?
so what then is the groove volume ?
now you 'know' that the depth of the o-ring is 70% of 1/16",
[find out the tolerances, and use the lower 'limit']
what then will groove's width be ?

this is pretty basic arithmetic, eh ?

now why cut a groove that small if such is not necessary ?

BTW, the bearer of bad tidings here; your design is quite seriously flawed
- Cathar's thread identifies the salient considerations,
which you are ignoring in favor of what you like the appearance of

build it, test it - many to go

Yeah, I'm told that I have my days, where I'm just "dense".

I think Utabintarbo understood what you were trying to convey. I'll double check (using my trusty calculator ).

I still haven't been through the entire thread (Cathar's). I wouldn't go as far as to say that the design is "seriously flawed", but it certainly does have a number of limitations, and a couple of non-sequitor sections:

1-The purpose of this radial design is primarily to reduce the overall flow restriction. Pending a full cube-res design, I believe that this has been accomplished.

2-The added benefit is that because of the channel design, the coolant will flow at a higher speed over the critical area (over the core), but the nozzle (center opening) does not reflect this. If it did, then the opening would be in the order of 1/4 inch (diameter), but that in turn affects the throughput through the fins. I am still working on this, but in the mean time, the design does allow for a drop-in nozzle, so for construction purposes, I believe that we are still on track.

3-I have made some templates to fit over my hand drawn fin pattern, and have found that a 3/8 inch opening would allow the flow to be seperated into 16 channels. In this configuration, the equivalent opening is (16 * 5 * 1 = 80 mm^2) at the channel area, where the nozzle opening is 3/8 aka 72 mm^2, which isn't much of any kind of nozzling.

4-With a 3/8 nozzle, there is a certain flow restriction, which may counter point #1, but strictly for cooling purposes, where it is critical. A small pump may not work well here, but I am certain that my Little Giant can handle it.

5-I have made many references to the core being 11 by 11 mm, when in fact it is smaller, more like 8 by 10 (rough approx). I have a template for this too.

6-The fabrication of this block is a very large factor. EDM is out, due to cost. I have yet to be able to reproduce Les' calculations on Cathar's block, and I am somewhat limited in calculating the thermal numbers for this block, as most tools do not account for a circular pattern, but it's not impossible to figure out, using a little averaging (adds error, but that's ok, I just want an idea). The numbers change at different radiuses (?), hence the name.

7-There is a flow optimization issue over the very center of the block. It has not been resolved to my satisfaction, yet.

8-There is a flow distribution issue, where the channels on the outside of the fin pattern won't have the same flow rate, but it's not a very large difference (depending on nozzle), and I plan to attempt to balance this by selecting the right openings on the top.

Overall, I believe that the block design will function, regardless of what's inside, so again, to call it "seriously flawed" is, IMO, out of touch. Since I'm still optimizing/calculating, it can be called "work in progress" (to Fixittt's frustration: he can't wait to get started!).

Note: my original idea did not have a top plate, but didn't have any fins either (except to hold the center barb). In that configuration, I believe that the design falls somewhere along with the Swiftech type blocks (open/flat plate category).

[BillA]

good to see that your mind is not closed to doubters

Cathar's thread can benefit you, but only if you read it - eh ?
suggest making 6 or 8 notes
some points are essential to the process, the sequential development of a design
truly, some choices FORCE others

you are trying to kiss all the girls at the very same time
ain't gonna happen that way

your #7 is the real #1

your words are obscuring your vision

a 'good' design is not a trip through a market, selecting the best of this and the best of that
rather it is the identification of the primary influences, their prioritizing, and their sequential optimization;
understanding which tradeoffs may be beneficial - and which less so

your design IS seriously flawed, and that you fail to see this means – to me – that you have not yet understood the design process itself

[nicozeg]

Just relax Bob, it was only a suggestion. It seemed to me that the only argument for deciding copper was being afraid of weakness. When Ben asked for glass, it make me clear that he prefer a transparent material; so my point was that the block could easily be made strong enough to use plastics for the top.

Myv is right; I made a very brute simplification of the problem. My intention was to do some quick numbers to show the advantages of fin continuity. I didn’t want to spend a lot of time in more precise calculations, because I’m very confident that for the small loads involved, it’s stiff enough by a big margin.

As for the added complications in the machining stage, they are by far compensated if machining a copper top can be avoided.

Further simplifications of the model can be made when using a plastic top. The o-ring channel can be eliminated and use that silicone film sealant someone mentioned. Even more, it could be used silicone adhesive and eliminate the need of bolts. It can give the block a cleaner look and avoid hole taping. I think this is ok with the KISS concept

I’m sorry if the only added work my suggestions imply is Bob’s drawing time.

[nicozeg]

Ok, I can do some real numbers calculations but I need that someone provides me with copper´s mechanical properties, mainly "elastic limit" and "elasticity module" (not sure about the correct name in english)

[utabintarbo]

Originally posted by nicozeg
Just relax Bob, it was only a suggestion. It seemed to me that the only argument for deciding copper was being afraid of weakness. When Ben asked for glass, it make me clear that he prefer a transparent material; so my point was that the block could easily be made strong enough to use plastics for the top.

This too was my original contention. And if I were any more relaxed I might soil myself!

Originally posted by nicozeg

As for the added complications in the machining stage, they are by far compensated if machining a copper top can be avoided.

Further simplifications of the model can be made when using a plastic top. The o-ring channel can be eliminated and use that silicone film sealant someone mentioned. Even more, it could be used silicone adhesive and eliminate the need of bolts. It can give the block a cleaner look and avoid hole taping. I think this is ok with the KISS concept

But this does not correlate with the KILL concept (Keep it looking 'L33t).

Originally posted by nicozeg

I’m sorry if the only added work my suggestions imply is Bob’s drawing time.

What?

Bob

[utabintarbo]

Originally posted by unregistered
good to see that your mind is not closed to doubters

Cathar's thread can benefit you, but only if you read it - eh ?
suggest making 6 or 8 notes
some points are essential to the process, the sequential development of a design
truly, some choices FORCE others

you are trying to kiss all the girls at the very same time
ain't gonna happen that way

your #7 is the real #1

your words are obscuring your vision

a 'good' design is not a trip through a market, selecting the best of this and the best of that
rather it is the identification of the primary influences, their prioritizing, and their sequential optimization;
understanding which tradeoffs may be beneficial - and which less so

your design IS seriously flawed, and that you fail to see this means – to me – that you have not yet understood the design process itself

Obscure references aside, what exactly are you talking about? I mean for the less-informed among us.

[myv65]

Originally posted by utabintarbo
Obscure references aside, what exactly are you talking about? I mean for the less-informed among us.

For a switch, Bill was relatively polite and I get to come in a say what he was really thinking whilst sounding like the hard case. Sorta like good cop, bad cop if you will. As an aside, Bill must not be feeling well today. Get well soon. LOL.

Bill means that Ben doesn't yet get how everything works together (or against each other). Ben has looked at many designs and noted the relative merits of each. Now he's trying to take all the "good" ideas and combine them into a single block. The various "good" traits are irrevocably tied to other traits and it is not so simple as merely "using all the good ideas at once".

As for Ben, few approaches beat hands-on experimentation to learn how things work. At best, this block of his is a starting point rather than a destination. A lot more experience and education in heat transfer would likely lead to a different first step. Believing that it will be the greatest thing since sliced bread would be naive.

Personally I wish Ben all the best in making his block a reality. I believe, however, that you need the mindset of "it's nothing more than a learning experience". Once he's made it, he would need to study how it works, where it falls down, how he could make it better. It's a refinement process and it's rarely if ever right the first time out the gate.

[utabintarbo]

Originally posted by myv65
For a switch, Bill was relatively polite and I get to come in a say what he was really thinking whilst sounding like the hard case. Sorta like good cop, bad cop if you will. As an aside, Bill must not be feeling well today. Get well soon. LOL.

Bill means that Ben doesn't yet get how everything works together (or against each other). Ben has looked at many designs and noted the relative merits of each. Now he's trying to take all the "good" ideas and combine them into a single block. The various "good" traits are irrevocably tied to other traits and it is not so simple as merely "using all the good ideas at once".

I guess my problem is one of style. Merely saying something is no good without saying why it is no good conveys nothing. It is merely pissing on someone elses idea. There are very few people here who are unwilling to take constructive criticism, key word being constructive. But criticism for its own sake makes one appear merely sanctimonious.

My 2 pfennigs...

Bob

[BillA]

Originally posted by unregistered
Ben
. . . .
build it, test it - many to go

from some posts back

and the only way you will shorten that cycle is to start actually thinking about what's going on

utabintarbo
sure seemed clear to me
1) read the references given
2) think about it until a measure of comprehension is attained
3) do it

the process I'm seeing here is a verbal circle jerk
a whole lotta talk
with minimal thought
all eye candy
no thermo or fluid mechanics (must get back to the basics)

-> hit the library !

(better form now myv65 ? - switching keeps 'em guessing)

Bob - posts crossed

no, I do not agree
something is worth what YOU pay for it, easy come - easy go
if I give you the answer it is worthless because it was free
BUT
if you have to read a 30 page thread, which has 6 or 8 real pearls hidden in it
then you have paid perhaps enough to remember 'the lesson'

on forums all posts have the same appearance, good or bad
as I said to Ben; if you don't care enough to read, why should I type for you ?

[bigben2k]

I am glad to see the animosity dissipate...

I have to confess, to BillA's remark, that this thread is somewhat representative of the process through which I am going, to develop this block. It is chaotic, approaches many aspects at either the same time, or in no particular order. As with software development, 80% is planning, 20% is coding (under the best circumstances). Since this is a part time effort on my part, I will certainly not make any scientific claims of any kind of breakthrough. As myv65 pointed out, I'm trying to use "the best of the best".

In this particular design, the aim is to optimize the flow where it is needed, and I believe that it is achieved with the "tube-in-tube" approach, combined with the radial pattern. As Cathar pointed out, the optimal copper to channel ratio he found to be ("between 1.5 and 0.8") is entirely applied here, where the ratio will vary between 1.5 and 0.75 . My numbers may turn out to be slightly different, but I won't know this until I've completed my calculations.

In the mean time, I view this thread as having what I call a "hack-and-slash" approach (a D&D expression refering to a simplistic "kill everything" campaign). There are many parts here, and some more in the e-mail exchanges between Utabintarbo and myself. Utabintarbo has made significant contributions (Thanks Bob!). All in all, I can see that there isn't a clearly defined approach to this, but most of the design has been inspired from an idea of mine, and from some of Cathar's results. That's where it all comes from, the rest is merely the details of an idea.

If this was an ordered development, the first thing for me to do would have been to recruit a specific number of people, so that we can list the parameters, define an approach, set up a schedule, and since this would become a collaborative effort, assign each member a task (except for non-participating team members). Then, and only then could I claim any kind of pseudo-scientific approach (Now tell me honestly BillA, would you have responded positively to such an invitation?)

To point the obvious:
this is a ProCooling forum, not NASA.


This entire effort is revealing of the many constraints a block designer faces, the most important of which is the construction. I have dreamed up many other blocks which were unfortunately impossible (or too expensive) to make.

Back to work.

At this point, I think that we should send Fixittt some kind of drawing, even if it's preliminary, because I have many unanswered questions in that area, and Fixittt doesn't appear willing to budge without one!

[Cathar]

Originally posted by bigben2k
This entire effort is revealing of the many constraints a block designer faces, the most important of which is the construction. I have dreamed up many other blocks which were unfortunately impossible (or too expensive) to make.

You know, I spent a lot of wasted time worrying about what was not possible based on what people were telling me. "Can't use mill bits smaller than 3mm or 1/8", etc. Plugging through the simulator I found that this was in fact the major limitation to making blocks any better than what they are today.

I gradually reduced the channel/wall thicknesses, down to 1mm which I knew was the smallest mill bit that is commonly available without getting into aerospace quality machine (and the huge cost jump that goes along with that), and knew then that I wanted to get my block made with 1mm channels.

Then I must've rang about 40 machine shops asking them

1) could it be done (in pure copper)
2) will you do it
3) how much

90% said no to #1
5% said no to #2
Of the 2 places who said yes to #3, only one was relatively enthusiastic and they were willing to try it out.

Was it expensive to get it prototyped? Hell yeah. It took a pretty large leap of faith to commit that kind of money just merely on an idea.

However I will say this. I learned more about structural and machining limitations in 1 hour of face to face talks with these guys than I could've learned through a few days of reading. There's the real engineer's approach to a design by looking at all the variables which involves design it right on paper the first time, and then there's the "on the ground" human intuition assessment of a design from a machinist with 40 years of experience in taking the jobs that everyone else said was too hard to do. Both work very well. The engineer's approach will be guaranteed to work, while the machinists approach will be correct 99+% of the time.

I never professed to have a full understanding of every stress variable in my design at the time I took it to the machine shop, but by the time they looked it over and made a few changes, that took about 1 hour of their time.

So basically, use the tools that are available to you. If you like your design, and want to see it get made, and have enough faith in it then the best thing you'll do is pull out the yellow pages, ring around to find someone who's willing to take the job on, then head down with your design in one hand and a cheque book in your back pocket that you're not afraid to open, and benefit from years of experience that you could never hope to pick up in a few days.

Sometimes you've just gotta take the leap.

[bigben2k]

Here here.

However, since I haven't resolved the central flow issue (#7), I don't feel that I have anything to even show to anyone right now (huh? what about this thread?) so until it's resolved, I'm not ready to put it into production. Otherwise, I think I've pushed Fixittt to his limit (maybe?).

The mount is becoming a larger issue. Utabintarbo pointed out to me this morning that my drawing doesn't work, but I haven't explored why yet.

The top material issue is "to be resolved", pending a sudden increase of knowledge on my part, or a structural engineer popping in here.

Also pending is my thermal calculation. In the spirit of "good science", I will try to recreate Les' numbers first, before I commit to calculate Radius' properties, but this takes time, which I have little of right now. Maybe in a week or so.

In the mean time, here's the latest drawing:

[bigben2k]

For the central flow issue, I have been looking at this (in my head) for some time:

blue: cutting wheel
orange: copper

As ya'll can see, the circular disk would leave a pointy pattern in an unfinished cut. If this was done from all four sides of the center, the result would be a "pointy pyramid", with 4 walls.

But I can't visualize it without some kind of 3D render (Utabintarbo?).

The original intent was to use an endmill, which would leave a completely different pattern in the middle.

The original idea had a perfectly square cut, which is not possible without some manual effort and/or special tools.

Without any feedback from the miller, I'm at a standstill on this issue.

[gone_fishin]

There is much to be said about making and testing and seeing for yourself. Cathar went through a refining process as his design progressed, blocks in hand, physical testing. That's the next step after theorizing. BTW, congratulations to you Cathar on finalizing a product

[BillA]

Ben
I spent 10 years on committee work at the national level (ASTM, API, etc)
I have very definite ideas about how I will NOT spend the balance of my life

I still don’t think you’re hearing what’s being said

I gave Cathar not a single answer (that I recall anyway)
but suggested areas of ‘interest’
which HE followed, and came up with HIS design

if I tell you what to do, are you then going to think its ‘your’ design ?
(I know the answer to this question, and its depressing)

why solicit answers from others ?
spend the time, learn it yourself, answer your own questions
(independence, initiative, self-reliance, blah blah blah– that’s my song, always)

#7
address the flow issue
THEN worry about machining it
you're still bassackwards

[bigben2k]

Originally posted by unregistered
Ben
I spent 10 years on committee work at the national level (ASTM, API, etc)
I have very definite ideas about how I will NOT spend the balance of my life

...and I'm happy for you.

You may not agree with the way that this development is going, and I understand that. I will however ask you to respect the fact that very few of us have the same level of knowledge and experience as you, and as such, if you wish to continue looking down at this, then by all means go ahead: we won't hold it against you.

Originally posted by unregistered
I still don’t think you’re hearing what’s being said

I gave Cathar not a single answer (that I recall anyway)
but suggested areas of ‘interest’
which HE followed, and came up with HIS design

if I tell you what to do, are you then going to think its ‘your’ design ?
(I know the answer to this question, and its depressing)

why solicit answers from others ?
spend the time, learn it yourself, answer your own questions
(independence, initiative, self-reliance, blah blah blah– that’s my song, always)

...and your comments are welcome. You do however have to understand that I cannot rely on a single source of information. (which makes your o-ring statements most difficult to deal with).

I don't expect anyone to give me the answer to #7, nor any other question, but I will openly state what issues I am encountering, in the hope of being pointed in the right direction.

This development has gone beyond my doing, to some extent, but it started that way anyways! I will claim the original idea as mine, even though I realize that it has probably already been done. I fully expect someone out there to chime in here at any time with "I did (something similar to) that, here's my result". It'll be a dissapointment, but at least I can honestly say that I wasn't copying someone else's work.

I will however sollicit some assistance (beyond what you would provide) for the structural integrity, in the form of concept, and possibly formulaes. I already have a fair idea of how to calculate the deflection of standard shapes, so if I have to "rough it" by using standard data available pretty much anywhere, then I'll have to go with that, and add a big safety margin. It may not be efficient, but it will work.

Originally posted by unregistered
#7
address the flow issue
THEN worry about machining it
you're still bassackwards

Of course this is "bassakwards", I agree.

IMO, this forum's purpose is to share ideas, so that we can learn from one another. As a result, most of the comments will address the simple issues, in no particular order, and some more complex ones, perhaps more as an overview. I take full responsability for the most complex ones (thermal property calcs).

The secondary purpose of this thread is to share the personal experience. I have found this to be mostly a Canadian thing, go figure.

I will address #7 when I'm good and ready to. I'm not happy aproaching it from a machining point-of-view, but that's otherwise what I'm open to hear right now.

[utabintarbo]

Originally posted by bigben2k
...

IMO, this forum's purpose is to share ideas, so that we can learn from one another. As a result, most of the comments will address the simple issues, in no particular order, and some more complex ones, perhaps more as an overview. I take full responsability for the most complex ones (thermal property calcs).

The secondary purpose of this thread is to share the personal experience. I have found this to be mostly a Canadian thing, go figure.

This IS the purpose of forums in general, as I see it. To share information, not information about links to information, nor obscure references to pearls of wisdom scattered about the web. To state that the information exists helps no one (especially if it is stated in a snide and unctuous manner) - everyone knows it exists. If that is all you have to contribute, you contribute nothing.

[/thread hijack mode]

Bob

[Alchemy]

bigben2k, you flatter me to suggest I could actually absorb all this information and have any useful information to offer in enough time to be of any service.

This design is more a mechanical engineering issue than a chemical engineering issue. With the sort of complex flow patterns you're discussing, I wouldn't be able to offer up much more than educated guesses about the design.

I suppose I could come up with some estimated performance specs given a number of conditions. That wouldn't take too long, but I'd need some more information before I started.

My current concern with this design is that the fins don't seem to disrupt the flow much, and will probably impede turbulence rather than improve it.

This isn't a bad thing, really. It might make a very effective high-flow-rate block.

Anyway, if you could give me the following info I could get started:

1) Estimated flow rates

2) Estimated heat dissipation (I'd assume ~100 watts)

3) Some info about the top mating piece for the block - at least enough to tell me something about the channels. I'm having trouble determining the current design and dimensions of the channels from your posts.

I'm a bit busy this week, so it may take a few days before I can get to work on this, but I hope whatever I find is helpful.

Alchemy

[bigben2k]

That would be very helpful, if you're willing to help.

I'd rather use a 100 W heat source, in an 8 by 10 mm area that's centered. That's an AMD Athlon core, overclocked.

I have yet to balance the flow in this thing, and it will depend on the size of the nozzle that I use. If I go with a 3/8 inch nozzle, then the flow splits 16 ways, in a 1mm wide channel that is 5 mm high. The copper fins are 1.5 mm wide. As you can observe, because of the 1mm cuts, there is a varying ratio of copper-to-channel from 1.5 to 0.75 . This block might have a nozzle that is 9/32 inch in diameter, which would force the flow to split 8 ways. Nozzle size is not final...

The top rests right on top of the fins, improving structural integrity. It may be made of copper, or polycarbonate. In any case, all channels are 5mm high, and 1 mm wide.

You should notice right away (?) that the flow isn't balanced at the outer edge: the flow is higher along the main 4 fins. I plan to balance this with the right openings in the top.

Flow rate: I will be using a "Little Giant" 2-MDQ-SC, which has a 14.4 feet max head, but otherwise capable of flow rates of more than 500 gph. See specs here I haven't done my homework yet so I can't give you an exact flow rate, but I have been shooting for 5 gpm (300 gph). 2 to 3 gpm (120 to 180 gph) would be more realistic.

You're otherwise correct: I'm not concerned so much (not at all actually) with turbulence as I am with flow speed.

I will also attempt to calculate the thermal properties, but I was hoping that you might have some wise words about how I'm going to optimize the flow over the very center of this block.

[bigben2k]

Here's my address (and full thought process!) to #7:


Option 1: extend the fins in the center area into the nozzle, in the shape of a blade.

Pros: will split the flow 4 ways, may add a bit more flow in the center
Cons: it was already split 4 ways. Effect would be negligeable


Option 2: extend the fins (same as #1) but wrap the inner hose tightly around them

Pros: might serve to put more flow in the middle
Cons: no provision for different nozzles, nozzle is tube size


Option #3: add a 1.5 mm needle in the middle

pros: none, really
cons: unnecessarily complex


Option 4: lower the fin height (cone) in the middle

pros: Excellent distribution
cons: no cooling from the fins (no fins!)


Option 5: same as #4, but from the bottom of the fins

pros: ?
cons: effect negligeable, impossible to do?


So the best solution being #4, a cone cut into the middle, there's still a number of issues (or sub-issues):
1-weaker structure
2-no cooling effect from fins

Answer:
The cone does not have to extend down to the baseplate. Is a compromise possible... not really.

How about a ball end mill, 6mm in diameter? Not much different than a cone. A cone cut would leave a triangle that ends in the center. This would be the reinforcement, as an extension from the top.

The structure at that point is not reinforced straight down by the top, regardless of any option, so the structure issue is minor, except for the rigidity provided by the solid main fins, as pointed out by Nicozeg. With a 9/32 nozzle, the radius is 3.57 mm, so with a fin height of 5 mm, the angle would be about 35 degrees from vertical. (relevance?)

Conclusion: cone cut in the center, about 35 degrees from vertical axis.

I still have a couple of options that I'm pondering. More when they're finalized.



Headache time.

[Fixittt]

Ok, I have to add on this too. I have talked with Ben, (Great guy) in PM about making this block. He is going to fund it. Granted its not going to cost an arm and a leg as would any other small order from a machine shop, because I have pulled a few strings.

I basicly told him to finish the design as to how he wants it, and I will try my damdest to make the sucker to his specs. Will it be possable, dont know untill we cut some copper. If it can be done, we can do it. Will it eat a bunch of 1mm endmills, prolly. At least untill we get the feed and depths right. Will it take forever and a day to machine? YUP....... Do I care? NOPE! Will I be proud to be some part of the venture. OHHH YEAH!

[jaydee]

Originally posted by Fixittt
Ok, I have to add on this too. I have talked with Ben, (Great guy) in PM about making this block. He is going to fund it. Granted its not going to cost an arm and a leg as would any other small order from a machine shop, because I have pulled a few strings.

I basicly told him to finish the design as to how he wants it, and I will try my damdest to make the sucker to his specs. Will it be possable, dont know untill we cut some copper. If it can be done, we can do it. Will it eat a bunch of 1mm endmills, prolly. At least untill we get the feed and depths right. Will it take forever and a day to machine? YUP....... Do I care? NOPE! Will I be proud to be some part of the venture. OHHH YEAH!

Yeah I am in to! If you (Ben) can come up with design I can work with I will also attemp to make this thing (and yes, in Copper). My mill works good with tiny endmills even with copper as that is what the thing was made for, small work. 1/8" endmills cut through it like butter so 1mm should work if I can get the mill to run slow enough.

Also fixittt, new website in my sig! If you need anything posted let me know. Slowly getting things moved over. And this site is here to stay! Bought the domain name this time.

[Alchemy]

Originally posted by bigben2k
I have yet to balance the flow in this thing, and it will depend on the size of the nozzle that I use. If I go with a 3/8 inch nozzle, then the flow splits 16 ways, in a 1mm wide channel that is 5 mm high. The copper fins are 1.5 mm wide. As you can observe, because of the 1mm cuts, there is a varying ratio of copper-to-channel from 1.5 to 0.75 . This block might have a nozzle that is 9/32 inch in diameter, which would force the flow to split 8 ways. Nozzle size is not final...

The top rests right on top of the fins, improving structural integrity. It may be made of copper, or polycarbonate. In any case, all channels are 5mm high, and 1 mm wide.

You should notice right away (?) that the flow isn't balanced at the outer edge: the flow is higher along the main 4 fins. I plan to balance this with the right openings in the top.

Flow rate: I will be using a "Little Giant" 2-MDQ-SC, which has a 14.4 feet max head, but otherwise capable of flow rates of more than 500 gph. See specs here I haven't done my homework yet so I can't give you an exact flow rate, but I have been shooting for 5 gpm (300 gph). 2 to 3 gpm (120 to 180 gph) would be more realistic.

You're otherwise correct: I'm not concerned so much (not at all actually) with turbulence as I am with flow speed.

I will also attempt to calculate the thermal properties, but I was hoping that you might have some wise words about how I'm going to optimize the flow over the very center of this block.

I assumed the channels were etched on the bottom to disrupt flow and cause turbulence. I didn't realize the fluid was actually going to be forced to flow within them.

I ran some calculations, and it looks like you're going to have totally laminar flow throughout most of this block - that is, everywhere but the entry where the fluid is striking the center of the block.

I hate to argue, but I really think this design isn't going to work well. You really, really need turbulent flow in this sort of application.

I think you would get improved performance if you affixed the top plate such that there was a gap between the top of the channels and the top plate - 5mm should do. This would also significantly decrease friction and allow for higher flow rates.

How much of a difference it would make, I can't say for sure. Since almost all heat transfer is going to occur directly below the cold water inlet (assuming you're placing that just above the center) most of the heatsink outside that area serves little purpose anyway. But you asked for my advice, so here it is.

Alchemy

[Cathar]

Originally posted by unregistered
I gave Cathar not a single answer (that I recall anyway)
but suggested areas of ‘interest’
which HE followed, and came up with HIS design

About this point:

Perhaps the single most important statement that came from Bill that sticks in my mind as driving the design my block was this:

"Think about how to decrease the thermal gradient of pure copper"

I really have to thank Bill for that statement.

There were subsequent discussions about improving nozzle geometry, but again, these were comments along the line of "Think about boosting water velocity".

So those were the two driving comments behind my design.

There were no direct statements of what to do, and I even requested such of Bill to not tell me anything directly.

[utabintarbo]

Originally posted by Alchemy
I assumed the channels were etched on the bottom to disrupt flow and cause turbulence. I didn't realize the fluid was actually going to be forced to flow within them.

I ran some calculations, and it looks like you're going to have totally laminar flow throughout most of this block - that is, everywhere but the entry where the fluid is striking the center of the block.

I hate to argue, but I really think this design isn't going to work well. You really, really need turbulent flow in this sort of application.

Alchemy

How deep would the channels need to be "etched" to alleviate this problem? Would sand or bead blasting do the trick?

Bob