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Mechanic7

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I'm a Mechanical engineer with no prior experience in designing flow systems.

I'm struggling with a hydraulic system that I have to design.

the number of unknowns is large. but maybe by dividing the system to small sections, a solution can be found.

I attached a schematic drawing to the thread,as well as some pages from a fluid mechanics book I have, and on which I rely in my calculations.

Basically, I need to design and optimize a system that will circulate water in 2 pipes.

first, I need the water to flow out of a reservoir, through a ∅50mm pipe.

the water then enter a pump.

Volume flow through the pump is 160 [liter/min].

after the pump there is a junction.

Most of the water will continue to the rest of the system (lower right section in the drawing)

__and return to the reservoir__,

but a small percentage of the water will have to flow through a narrower pipe (with an unknown diameter ∅Z)

This pipe will eventually

__converge__at its end, in order to increase the speed of the water, flowing into the box shown on the top. at this convergence the pipe diameter should be ∅X (∅X<∅Z).

the box is actually a rectangular prism,

__not open to atmosphere.__

its cross-section size is about 20x20mm, and the height is about 80mm.

Conditions in the prism should be:

- Water flow - between 0.5 [liter/min] to 5 [liter/min]
- Formation of air bubbles should be as low as possible (clear flow).
- Water should fill the
__entire__box,__without dead regions__(would love to hear what you think about that possibility considering the current design - is it possible to achieve? do I need turbulent or laminar flow for that? )

__slower__from that box, so the pipe diameter at the box outlet should be

∅Y and then diverge back to the same pipe diameter before the box (e.g. ∅Z). this means ∅X<∅Y<∅Z.

After the water flows out of the box it has to flow towards the main line (∅50mm) and back into the pump,

and vise versa.

I know that I should probably use the Bernoulli equation and take into account losses (using Darcy-Weisbach friction factor)

I find it very confusing to understand where to use [ΔP] and where to use [ΔP loss] (these 2 terms show in the pages I attached)

the givens are:

Total flow rate: 160 [liter/min]

Pressure before the pump: (-0.1)[bar]

pressure after the pump: 0.7[bar]

main line diameter: ∅50mm

especially I would like to know the volume flows, pressures, water speed at all the points I marked in the

__smaller pipe.__and of course the required diameters, including the ones in the convergence and divergence inside the box.

There is also

__1 more question__I wrote

__on the drawing itself__.

I can't seem to understand where to start solving this problem and will appreciate any help you can offer.

Thanks a lot in advance!