Pump Characteristic Graph

Michal Krasowski
Michal Krasowski Altair Community Member
edited October 1 in Community Q&A

Good morning All,

I wanted to consult with you my way of my simplified thinking and if it is somehow correct- in terms of analyzing hydraulic system characteristics in Activate 2024.

First of all- the main goal of the model is to be able to test quickly some different pump types and their configuration, together with components that are connected in that circuit and specify the flow distribution and operating point of pumps.

As a input I just want to be able to specify the pumps Pressure(Flow) characteristic (same as Pump Head graph below), as well as components pressure drop characteristics (same as System Head graph below).

image

 

All the components generating pressure drop I just modeled as ResistorTableQpx with manual table that specifies pressure drop value vs flow graph.

image 

And the questionmark is about the best way of modeling the pump, as I do not care so much about the inertia topics, and there are no special valves or components used, so I thought that I will just use Variable Flow Pump and Lookup table to generate a loop. (so the pump flow is just max. flow and the lookup table in loop is defining percentage of max flow that is being used)

System seems to work and match some excel system curves, but it is sometimes slow and sometimes some problems occur, when assembly reaches higher level of complexity.

image

So this is why I just wanted to ask you about some hints, as it is just possible that I am trying to do something that can be done in much more simple way and maybe creating such a loops that I did is slowing it down and might be useless at complex models.

Cause maybe is it better to just recalculate the graph for the mechanical properties like RPM and Torque and to specify the loop based on that and Fixed Displacement Pump?

image

So in the end- long story short:

If you had pressure(Flow) graphs of pumps and components- what would be the best way of approaching it in your opinion?  Just for me not to try to reinvent something and analyze it, when the solution is already there!

Thank you in advance!!!

Michal

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Answers

  • Orestis_YB
    Orestis_YB
    Altair Employee
    edited October 1

    Hello Michal,

    I don't have a complete picture of how your model is connected but I don't see anywhere volume components. That may be your issue. I would suggest to check some Demo Models (press F7 to access Demo Browser) under HydraulicsByFluidon.
    image

    Pump test may be similar to what you are describing. Also here you can find an introductory e-learning on Twin Activate for Hydraulics simulation https://learn.altair.com/course/view.php?id=495 .  Hope this helps!

    Best regards,
    Orestes.

  • RoKet
    RoKet
    Altair Employee

    Hi Michael,

    All pumps already have a loss characteristic, but it's a linear one (leakage through gap). If you want to define your own characteristic, you can use a look-up table (as you already did). If the suction inlet is connected to tank, you can use a flow source instead of a pump.

    grafik.png

    You can use also the VariableFlowPump (as you also already did). The input is relative displacement (between 0 and 1), so you can use the same simple system as I used with flow source but with relative displacement instead of absolute flow.

    Ronald

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