New design idea.

[Gulp35]

How did you cut out the tubes?

[leejsmith]

with a dremel router bench but they are fairly well spaced apart.
also this is sized to cover a p4 heat spreader not amd core.

i dont think i could do it for and amd core.

[BaThMaN]

here's the how I did it


kinda confused on how I'll center the jets and holes (planning solder it)...

I think ill start from scratch all over again...

this time, the top 2 plates are semi-full sized...

started this project last 1st week of April... up to now dont have any idea how could I finish it ; just dont have that spare time...

[sevisehda]

I'm a little fuzzy on this jet thing.



In model A the jets are formed through a hole in polycarb and then are aimed at a corresponding divit. In b the jets are forced into the divit by a projection of copper tubing or other material. Is there a preference? Personally I would thing in A the wash from the central divits would force the other jets off there mark. While in B you'd be assured the water ended up in the right spot. Any comments?

Also has anyone tried placing 2 pumps inline to up the pressure? Fire trucks often have 2 pumps that can be switched from parallel to series. In parallel flow is high while pressure is low. But to shoot further they switch to series in order to up the pressure and shoot further.

[Gulp35]

I'm planning on using 2 maxijet 1200's in serial but the johnson pump (refered to in another thread) seems to have better performance and for less wattage input to the water.

[Cathar]

Originally posted by sevisehda
In model A the jets are formed through a hole in polycarb and then are aimed at a corresponding divit. In b the jets are forced into the divit by a projection of copper tubing or other material. Is there a preference? Personally I would thing in A the wash from the central divits would force the other jets off there mark. While in B you'd be assured the water ended up in the right spot. Any comments?

Have implemented both A and B.

A allows for higher density, which can somewhat offset the jet deflection.

B is definitely much more efficient at any given jet density.

[leejsmith]

i made these simulations using real flow and it shows the advantage of the cup base over a drill shape and flat.

first flat base dimple



next drill bit shape base



and last cup base



you can see the cup shape helps the water flow out of the dimple quicker over the same period of time in this case 11 frames with the same water jet in each simulation.

Hope this helps

Lee

[jaydee]

Thats excellent Lee! Looks like I need to order up some new ball nosed endmills!

[bigben2k]

Nice work indeed Lee!

Jaydee, maybe you didn't get it, but if it flows out faster, then it's not inpinging correctly. The only thing the cup does, is turn the flow into a fast, lateral, over the baseplate. Look at it like WhiteWater, in the side-to-side configuration.

For me, it shows that the dimple (first one) is the best design. Now to tweak it...

[leejsmith]

i thought the cups was the best too. but i see what you mean with the flat base giving better impingment.

guess this idea of a flow director at the base of the tube will make things worse.

[jaydee]

Originally posted by bigben2k
Nice work indeed Lee!

Jaydee, maybe you didn't get it, but if it flows out faster, then it's not inpinging correctly. The only thing the cup does, is turn the flow into a fast, lateral, over the baseplate. Look at it like WhiteWater, in the side-to-side configuration.

For me, it shows that the dimple (first one) is the best design. Now to tweak it...

HA! Your right. I was thinking backwards again.

[utabintarbo]

Originally posted by bigben2k
Nice work indeed Lee!

Jaydee, maybe you didn't get it, but if it flows out faster, then it's not inpinging correctly. The only thing the cup does, is turn the flow into a fast, lateral, over the baseplate. Look at it like WhiteWater, in the side-to-side configuration.

For me, it shows that the dimple (first one) is the best design. Now to tweak it...

2 questions for Lee:

1. What will happen with a fillet applied to the first dimple (bullnose cut)?

2. What software did you use to get those pics?

Enquiring minds want to know!

Bob

[Althornin]

Originally posted by leejsmith
i thought the cups was the best too. but i see what you mean with the flat base giving better impingment.

guess this idea of a flow director at the base of the tube will make things worse.

not at all
The flow director IS an improvement. There is no gain offered by impingment upont he top surface. You want the water to exit as fast (and with as little pressure drop) as possible.

[leejsmith]

Originally posted by utabintarbo
2 questions for Lee:

1. What will happen with a fillet applied to the first dimple (bullnose cut)?

2. What software did you use to get those pics?

Enquiring minds want to know!

Bob

whats a bullnose cut/fillet ? sorry but i dont do any machine work

the software is realflow but it's a trial version and i cant export the particals into anything so i just screen grab each frame and then make a animated gif file from them.

[hara]

Where can we get realflow? Trial's fine

[leejsmith]

http://www.nextlimit.com/

[leejsmith]

Originally posted by utabintarbo
2 questions for Lee:

1. What will happen with a fillet applied to the first dimple (bullnose cut)?

2. What software did you use to get those pics?

Enquiring minds want to know!

Bob

is this what you mean



what if you have something at the base of the dimple that whould make the water swirl around ? or a pattern in the walls of the dimples.

[jaydee]

Originally posted by leejsmith
is this what you mean



what if you have something at the base of the dimple that whould make the water swirl around ? or a pattern in the walls of the dimples.

I am not so sure that is possible, or practicel, to make. If we hold to Cathars current version the holes are less than 1/16" and probably more like +-1mm. Not going to be easy to make any kind of special "feature" in the bottom of one of those holes aside from the natural shape of the tooling.

[leejsmith]

i agree the dimples are so small it would be impossible to do anything else. But utabintarbo asked for the bullcut so i did it.

does cathars design have flat dimple bases or cup shape ? i thought he had cup shape as he got the idea from a cup under a tap.

[jaydee]

Originally posted by leejsmith
i agree the dimples are so small it would be impossible to do anything else. But utabintarbo asked for the bullcut so i did it.

does cathars design have flat dimple bases or cup shape ? i thought he had cup shape as he got the idea from a cup under a tap.

i am pretty sure he said they were going to use a ball nosed endmill, so if they are it would be cup shaped.

Now we have conflicting reports here! One side says the Cups are better and one side says the flat botton is better.

If you go with the flat bottom the flow and pressure rate may suffer, but you should get more direct pounding against the bottom of the hole to reduce the boundry layer.

Or if you go with the cup, the water flows pretty nice and it should get the flow rate and pressure up and may also reduce the boundry layer because of that?

Or am I all messed up?

[Cathar]

Originally posted by leejsmith
does cathars design have flat dimple bases or cup shape ? i thought he had cup shape as he got the idea from a cup under a tap.

Flat bottomed cup with squared sides (not bullnose) yields the best results and is what I use.

You want impingement, not smooth transitions.

Sometimes I drop old ideas but don't update the on-line material.

[Cathar]

Originally posted by jaydee116
Or if you go with the cup, the water flows pretty nice and it should get the flow rate and pressure up and may also reduce the boundry layer because of that?

Or am I all messed up?

Sometimes I deliberately try to be a little confusing - for obvious reasons. I did also leave hints here and there for those who were really listening, that I was actually going the other way.

Since you're all onto it now though, yes, the flat bottom is better (as I said above).

The bulk of the pressure drop happens at the jet entry orifice as a result of adding restriction here to boost water velocity before impingement takes place. The actual pressure-drop as a result of what's going on inside the cup in quite minor compared to the jet acceleration restriction.

Flow rate differences between balled and flat-bottomed cups were basically indistinguishable.

[leejsmith]

Originally posted by Cathar
Flat bottomed cup with squared sides (not bullnose) yields the best results and is what I use.

You want impingement, not smooth transitions.

Sometimes I drop old ideas but don't update the on-line material.

thanks cathar

[hara]

I understand the reasoning behind this. Water is colliding perpendicular to the surface instead of "sliding". But then again, is the boundary layer mostly reduced at 90 degrees? I read somewhere on these forums that 70 degrees was best. Don't know if that holds in this context.

[jaydee]

Alrighty then, back to the standard flat bottom center cutting endmill. Maybe it was the ball nose endmill you where using for the cuts in the poly top....

*Tried to screw head back on strait**Realizes I am just kidding myself trying*

Good stuff Cathar! I got to order some new tooling for the mill. The laser wasn't up to snuff. It will do small deep channels but they look like ass (big hairy gorilla ass at that) and you cannot really control depth with it as that isn't what it was made for.