Hydraulic Pipeline

[Jerome]

Hi all,

I don't know how to exactly parametrize the hydraulic pipeline block.
In case I have a pipe which is 5 Meters long and outlet is 2 meters above fluid-level, what is the "Aggregate equivalent length of local resistances" -

Thank you for your help
Cheers
Jerome

[TideMan]

Post by Jerome
Hi all,
I don't know how to exactly parametrize the hydraulic pipeline block.
In case I have a pipe which is 5 Meters long and outlet is 2 meters above fluid-level, what is the "Aggregate equivalent length of local resistances" -
Thank you for your help
Cheers
Jerome

I guess you're using Simulink, which I don't have.
I've done a fair bit of pipeline hydraulics outside of Simulink, but I
have no idea what "Aggregate equivalent length of local resistances"
means. It's gobbledygook.
I empathise with you.
Why not use 5 and see what happens?

[Arnaud Miege]

Post by Jerome
Hi all,
I don't know how to exactly parametrize the hydraulic pipeline block.
In case I have a pipe which is 5 Meters long and outlet is 2 meters above
fluid-level, what is the "Aggregate equivalent length of local
resistances" -
Thank you for your help
Cheers
Jerome

Hi,

I assume you are referring to the hydraulic pipeline block in SimHydraulics:
http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/hydro/ref/hydraulicpipeline.html

Have a look at the documentation:
"Aggregate equivalent length of local resistances

This parameter represents total equivalent length of all local resistances
associated with the pipe. You can account for the pressure loss caused by
local resistances, such as bends, fittings, armature, inlet/outlet losses,
and so on, by adding to the pipe geometrical length an aggregate equivalent
length of all the local resistances. This length is added to the geometrical
pipe length only for hydraulic resistance computation. The fluid volume
depends on pipe geometrical length only. The default value is 1 m."

If you want to negletct those effects, you can set it to 0 or some small
value.

HTH,

Arnaud

[Jerome]

Post by Arnaud Miege

Post by Jerome
Hi all,
I don't know how to exactly parametrize the hydraulic pipeline block.
In case I have a pipe which is 5 Meters long and outlet is 2 meters above
fluid-level, what is the "Aggregate equivalent length of local
resistances" -
Thank you for your help
Cheers
Jerome

Hi,
http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/hydro/ref/hydraulicpipeline.html
"Aggregate equivalent length of local resistances
This parameter represents total equivalent length of all local resistances
associated with the pipe. You can account for the pressure loss caused by
local resistances, such as bends, fittings, armature, inlet/outlet losses,
and so on, by adding to the pipe geometrical length an aggregate equivalent
length of all the local resistances. This length is added to the geometrical
pipe length only for hydraulic resistance computation. The fluid volume
depends on pipe geometrical length only. The default value is 1 m."
If you want to negletct those effects, you can set it to 0 or some small
value.
HTH,
Arnaud

Hi Arnaud,
thanks for your prompt response.
Exactely that is the block I'm refering to.
In my assumption I only want to account for a height difference between inlet(Tank level) and outlet of 2 Meters. no other losses such as mentioned.
Is there a formula with which I can calculate the Aggregate equivalent length of local resistances" (L_eq)
Cheers,
Jerome

[Arnaud Miege]

Post by Jerome
Hi Arnaud,
thanks for your prompt response.
Exactely that is the block I'm refering to.
In my assumption I only want to account for a height difference between
inlet(Tank level) and outlet of 2 Meters. no other losses such as
mentioned. Is there a formula with which I can calculate the Aggregate
equivalent length of local resistances" (L_eq)
Cheers,
Jerome

Then I suggest you neglect this and set it to zero. Note however, that the
hydraulic pipeline block does not account for gravity effects (i.e. it
assumes that both extremities are at the same height). If you want to
include gravity effects, then you need to use the low-pressure version of
the block (available since R2009a):
http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/hydro/ref/hydraulicpipelp.html

HTH,

Arnaud

[Jerome]

Post by Arnaud Miege

Post by Jerome
Hi Arnaud,
thanks for your prompt response.
Exactely that is the block I'm refering to.
In my assumption I only want to account for a height difference between
inlet(Tank level) and outlet of 2 Meters. no other losses such as
mentioned. Is there a formula with which I can calculate the Aggregate
equivalent length of local resistances" (L_eq)
Cheers,
Jerome

Then I suggest you neglect this and set it to zero. Note however, that the
hydraulic pipeline block does not account for gravity effects (i.e. it
assumes that both extremities are at the same height). If you want to
include gravity effects, then you need to use the low-pressure version of
http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/hydro/ref/hydraulicpipelp.html
HTH,
Arnaud

Hi Arnaud,
Thx for your Help.

Jerome