WOLFRAM SYSTEM MODELER

ControlledOrifice

Controlled restriction

Wolfram Language

In[1]:=
SystemModel["Hydraulic.Restrictions.ControlledOrifice"]
Out[1]:=

Information

This is a model of a controlled restriction. 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 (7)

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

Connectors (3)

port_a

Type: Port_a

Description: Port for hydraulic fluid (filled icon)

port_b

Type: Port_b

Description: Port for hydraulic fluid (unfilled icon)

sNorm

Type: RealInput

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

Components (1)

medium

Type: Medium

Description: Medium in the component

Used in Components (22)

Straight4Port

Hydraulic.Valves.DirectionalControl.Internal.States

Basic building block for directional control valves

CrossOver4Port

Hydraulic.Valves.DirectionalControl.Internal.States

Basic building block for directional control valves

Diagonal4Port

Hydraulic.Valves.DirectionalControl.Internal.States

Basic building block for directional control valves

Floating4Port

Hydraulic.Valves.DirectionalControl.Internal.States

Basic building block for directional control valves

Open4Port

Hydraulic.Valves.DirectionalControl.Internal.States

Basic building block for directional control valves

Tandem4Port

Hydraulic.Valves.DirectionalControl.Internal.States

Basic building block for directional control valves

V22

Hydraulic.Valves.DirectionalControl.Internal

Partial valve with two ports and two states

V32

Hydraulic.Valves.DirectionalControl.Internal

Partial valve with three ports and two states

V33

Hydraulic.Valves.DirectionalControl.Internal

Partial valve with three ports and two states

V63

Hydraulic.Valves.DirectionalControl.Internal

Partial valve with six ports and three states

CheckValve

Hydraulic.Valves.DirectionalControl.Internal

Static check valve

ShuttleValve

Hydraulic.Valves.DirectionalControl.Internal

Static shuttle valve

DualPressureValve

Hydraulic.Valves.DirectionalControl.Internal

Static dual pressure valve

PilotOperatedCheckValve

Hydraulic.Valves.DirectionalControl.Internal

Static pilot-operated check valve

UnloadingReliefValveWithReversedPilot

Hydraulic.Valves.FlowControl.Internal

Static unloading relief valve with pilot ratio applied to port_a

VariableTurbulentThrottle

Hydraulic.Valves.FlowControl

Controlled restriction

PressureReliefValve

Hydraulic.Valves.PressureControl.Internal

Static pressure relief valve

PressureReducingValve

Hydraulic.Valves.PressureControl.Internal

Static pressure reducing valve

UnloadingReliefValve

Hydraulic.Valves.PressureControl.Internal

Static unloading relief valve

PressureCompensatingValveNormallyOpen

Hydraulic.Valves.PressureControl.Internal

Static pressure compensating valve

PressureCompensatingValveNormallyClosed

Hydraulic.Valves.PressureControl.Internal

Static pressure compensating valve

TankWithOutlet

Hydraulic.LiquidContainers

Model of a tank with environment pressure at inlet, hydrostatic pressure at the bottom, and an outlet orifice