variableorifice

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variableorifice

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Iconic Diagrams\Hydraulics\Restrictions

Use

Domains: Continuous. Size: 1-D. Kind: Iconic Diagrams (Hydraulics).

Description

This model describes the laminar/turbulent flow through an orifice if no cavitation occurs. The flow depends on the pressure difference:

 

dp = pa.p - pb.p;

phi = sign(dp) * Cd * A * sqrt( (2/rho) * abs(dp) ) + GLeak * dp;

 

Here Cd is the discharge coefficient that normally has a value between 0.55 and 0.7 and A is the area of the orifice opening. The area A is given as an input signal.

Orifice

The pressure at both ports has a lower limit that is equal to the vapour pressure. Therefore the actual equations used in this component are:

 

p1_lim = if pa.p < p_vapour then p_vapour else pa.p end;

p2_lim = if pb.p < p_vapour then p_vapour else pb.p end;

dp = p1_lim - p2_lim;

Interface

Ports

Description

pa, pb

Both terminals of the hydraulic component.

Causality

 

fixed volume flow out pa

fixed volume flow out pb

 

Input

 

A

Orifice Area [m2], A >= 0.

Parameters

 

rho

GLeak

Cd

Mass density of the fluid [kg/m3].

Conductance of the laminar leakage flow [m3/s.Pa], GLeak >=0!

Discharge coefficient [], Cd >=0!