Help with calculating, with "jets"....

Albigger · 12-05-2002, 01:14 AM

Basically, I'm working on some different jet designs (for direct die, mainly), or at least starting to.

I want to know how one would go about calculating how the water "spreads out" from the nozzle after it leaves the nozzle.

For example, lets say I have a .25" thick material, in which I have a rectangular slot that is straight walled through, with dimensions a " x b " and I'm forcing the water through at some known flowrate/velocity.

I have to place this nozzle some optimum distance from the cpu, but in doing so won't the water coming out of the nozzle tend to spread out? How do I calculate the horizontal velocity of the water after it leaves the slot? How much the water spreads out is of obvious importance, as you want to make sure the full cpu die is receiving the benefits of the high velocity water.

From what I've been reading (and attempting to understand) this is a lot more complicated than it first seems....

bigben2k · 12-05-2002, 08:51 AM

Try this:
http://www.flomerics.com/

Nick C · 12-05-2002, 11:01 PM

Howdo you use/ buy that program? I can't find anything

bigben2k · 12-06-2002, 09:00 AM

Hum... There are a number of on-line calculators. Check electronicooling.com, or google.

If Les was here, he'd link you straight up.

ezlid · 12-07-2002, 05:40 PM

Talk about tricky!
Not doing the calcs. but the mechanics. The jet block would have to be very fast draining into a collector( res.?) so that it doesn't fill with coolant. Otherwise, the block will just like any other, except with a very restricted feed due to the jet design. I think the res. would need to be quite large to allow all the air bubbles to dissapate.

As far the water spreading out, it all depends on your design. You can have it in a single solid, high velocity stream or multiple, lower velocity streams. I mention multiple streams, because there will a lot of splashing from the stream hitting the opposite wall. Multi streams could maximize the cooled area. You also have to figure in gravity, although the block would have to extend out the side of the case before that really became part of the equation.

My 2 cents. Interesting idea.

MadDogMe · 12-08-2002, 03:31 AM

There won't be any bubbles, that kind of pressure won't be achieved with the kind of pumps used, it should'nt need a reservoir either, just a 'wide open' outlet so the impingment~pressure is'nt negated by back~pressure. I think large diam' tubing(3/4 @ least) is gonna play a part in impingment cooling, no point loosing head on restrictive tubing when it's vitaly needed at the block...

12-05-2002, 01:14 AM	#1
Albigger Cooling Savant Join Date: Sep 2002 Location: ohio Posts: 140	Help with calculating, with "jets".... Basically, I'm working on some different jet designs (for direct die, mainly), or at least starting to. I want to know how one would go about calculating how the water "spreads out" from the nozzle after it leaves the nozzle. For example, lets say I have a .25" thick material, in which I have a rectangular slot that is straight walled through, with dimensions a " x b " and I'm forcing the water through at some known flowrate/velocity. I have to place this nozzle some optimum distance from the cpu, but in doing so won't the water coming out of the nozzle tend to spread out? How do I calculate the horizontal velocity of the water after it leaves the slot? How much the water spreads out is of obvious importance, as you want to make sure the full cpu die is receiving the benefits of the high velocity water. From what I've been reading (and attempting to understand) this is a lot more complicated than it first seems....

12-05-2002, 08:51 AM	#2
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	Try this: http://www.flomerics.com/ __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

12-06-2002, 09:00 AM	#4
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	Hum... There are a number of on-line calculators. Check electronicooling.com, or google. If Les was here, he'd link you straight up. __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

12-05-2002, 11:01 PM	#3
Nick C Cooling Neophyte Join Date: Sep 2002 Location: OREGON Posts: 62	Howdo you use/ buy that program? I can't find anything

12-07-2002, 05:40 PM	#5
ezlid Cooling Neophyte Join Date: Sep 2001 Location: Houston, TX Posts: 55	Talk about tricky! Not doing the calcs. but the mechanics. The jet block would have to be very fast draining into a collector( res.?) so that it doesn't fill with coolant. Otherwise, the block will just like any other, except with a very restricted feed due to the jet design. I think the res. would need to be quite large to allow all the air bubbles to dissapate. As far the water spreading out, it all depends on your design. You can have it in a single solid, high velocity stream or multiple, lower velocity streams. I mention multiple streams, because there will a lot of splashing from the stream hitting the opposite wall. Multi streams could maximize the cooled area. You also have to figure in gravity, although the block would have to extend out the side of the case before that really became part of the equation. My 2 cents. Interesting idea.

12-08-2002, 03:31 AM	#6
MadDogMe Thermophile Join Date: Aug 2002 Location: Just shut up ;) ... Posts: 1,068	There won't be any bubbles, that kind of pressure won't be achieved with the kind of pumps used, it should'nt need a reservoir either, just a 'wide open' outlet so the impingment~pressure is'nt negated by back~pressure. I think large diam' tubing(3/4 @ least) is gonna play a part in impingment cooling, no point loosing head on restrictive tubing when it's vitaly needed at the block...

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