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Re: Parameters of Centrifugal Pump in SimHydraulics. The help is very necessary!
Posted:
Apr 18, 2008 9:47 AM
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In article <fua667$1bd$1@fred.mathworks.com>, Evgeny wrote:
> Prompt how correctly to set Centrifugal Pump parameters.
>
> I use "By two 1D characteristics".
>
> Parameters Q-P [0 0.02 0.04 0.06 0.08 0.1 0.12] m^3/s
> Pressure P [4.4 4.8 5.2 5.2 4.8 4 2.4] atm
>
> Parametres N-Q [0 0.02 0.04 0.06 0.08 0.1 0.12] m^3/s
> N [2800 3100 3600 3900 4200 4800 5000] W
>
> Reference density 1000 kg/m^3 for water as I understood
>
> Reference angular velocity 3000 rpm
>
> I submit on an input 3000 rpm and it should turn out Q ~ =
> 0.07 m^3/s at the expiration in atmosphere and P ~ = 4.4
> atm at the closed orifice.
>
> I have hydraulic flow rate turns out negative ((((
>
Around here we do lots of hydraulic modelling/simulation in Simulink
(although we use our own models, not SimHydraulics - but the principles
are the same).
Just because the pump will generate a positive head at the set speed
does not mean the flow will necessarily be forwards. What about the
pressure differential across the pump in the service conditions? If
back-pressure-differential (outpet pressure less suction pressure)
exceeds the pump head, then the flow will go backwards.
I don't know how good the pump modelling is in SimHydraulics; but a
complete pump model should have a characteristic in all four quadrants
of the head/flow curve (all combinations of +/-ve head and flow).
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