Flow calculation through 3 holes that feed into another thru hole

[goodguy1405]

I am needing help to calculate the flow through this piece. I have attached a photo stating the question. Thanks for any help.

 

[MikeHalloran]

For liquid flow, the smallest hole will tend to dominate the impedance of the assembly, so you will get pretty close by just worrying about the single hole.

What's the fluid?

Are the dimensions in inches or mm or furlongs or what?

Do you have a curve for the pump or whatever induces the flow?





Mike Halloran
Pembroke Pines, FL, USA

 

[DubMac]

I must be missing something. You say 40 GPM flow on the drawing; I'm guessing 40/3. If it is a positive displacement pump, then you flow will be determined by the speed you run your pump, not the size of the holes. Size of the holes would determine pressure (with a few other fluid variables included).

With a centrifugal pump, then the size of the holes WOULD determine the flow; but as Halloran says: we gotta see pump curve to go further.

 

[goodguy1405]

Thanks for the responses. The fluid median is drilling mud. The fluid comes into the motor at 40 GPM then channels through the 3 .35 diameter holes that feeds into the .35 diameter thru hole(as seen in the pic). Will the flow rate change, due to it now going through 3 holes versus 1? I know the velocity changes but by how much? What equations are best for this scenario? Again thanks for the responses. All help is appreciated.

 

[goodguy1405]

The dimensions are in inches. Positive displacement motor. Forgot to answer that part.

 

[racookpe1978]

Are you sure about that?

40 GPM of drilling mud (a very heavy, viscous fluid) going through 3x 0.35 dia holes? You'd have troubling even getting 10 GPM through.

 

[casflo]

The best approach could be to calculate the holes as thick orifices. Search in Google for documents about "fuel injector nozzles". These devices are very similar to this type of holes.
An additional problem here is the fluid. You must know its density and viscosity to do the calculations.
casflo

 

[goodguy1405]

Thanks for the responses. I used the calculation Flow rate (in^3/s)= GPM x 231/60 to give me 154 in^3/s. Then I used equation velocity (ft/s)= Flow rate(in^3/s)/(12 x Flow area (in^2)= 45 ft/s for 3 holes and 66 ft/s for 2 holes and 133 ft/s for one holes. Assume it is a ideal fluid running through the tool. How am I doing so far? Thanks...

 

[DubMac]

Maybe I made my martini too strong tonight, but I'm still not getting why you are trying to calculate flow when you have already said the flow is 40 GPM. That won't change, appreciably, with a PD pump. Mass in = mass out.

What am I missing?

 

[goodguy1405]

Well with one hole the flow rate is 40 GPM through it but with 3 holes I believe each hole will take a portion of the 40 GPM through it. It will then feed back into the main through hole to the bit at 40 GPM. I may be wrong but that's why I am here to find out. Thanks for the help and have a martini on me.