WOLFRAM SYSTEM MODELER

VariableTurbulentThrottle

Controlled restriction

Diagram

Wolfram Language

In[1]:=
SystemModel["Hydraulic.Valves.FlowControl.VariableTurbulentThrottle"]
Out[1]:=

Information

This is a model of a controlled restriction with lumped volumes. The opening area A is controlled with a signal sNorm, normalized between -1 and +1. The area remains at until sNorm has exceeded the overlap parameter. When sNorm reaches 1, the area A equals the parameter . When sNorm is between overlap and 1, the area A follows the equation below:



The flow through the orifice is proportional to the square root of the pressure drop:



where
A:Opening area
:Maximum opening area
:Minimum opening area
sNorm:Normalized control signal
overlap:The orifice does not start to open until sNorm has exceeded this value
:Mass flow rate
:Fluid density
:Discharge coefficient
:Pressure difference between ports a and b

Implementation

The flow equation is linearized for pressure differences near zero to increase numerical stability.

Reference

K. Gieck and R. Gieck, Engineering Formulas, 7th ed., Germering, Germany: Gieck Publishing, 1997 p. N7.

Parameters (8)

medium

Value: Oil()

Type: Medium

Description: Medium in the component

Gleak

Value: 1e-020

Type: PressureDependentLeakage (m³/(s⋅Pa))

Description: Conductance of closed valve

Aleak

Value: (Gleak * ReCr * medium.nu * medium.rho * sqrt(Modelica.Constants.pi) / (4 * Cd ^ 2)) ^ (2 / 3)

Type: Area (m²)

Description: Minimum opening area

AMax

Value: 0.001

Type: Area (m²)

Description: Maximum opening area

Cd

Value: 0.62

Type: Real

Description: Coefficient of discharge for the opening

ReCr

Value: 12

Type: Real

Description: Critical Reynolds number

overlap

Value: 0

Type: Length (m)

Description: Normalized position when the opening is closed

V

Value: 0.0001

Type: Volume (m³)

Description: Volume of component

Connectors (3)

port_b

Type: Port_b

Description: Port for hydraulic fluid (unfilled icon)

port_a

Type: Port_a

Description: Port for hydraulic fluid (filled icon)

sNorm

Type: RealInput

Description: Normalized position of control valve (-1 - 1)

Components (4)

medium

Type: Medium

Description: Medium in the component

volume_a

Type: Volume

Description: Fixed volume with fluid storage

controlledOrifice

Type: ControlledOrifice

Description: Controlled restriction

volume_b

Type: Volume

Description: Fixed volume with fluid storage