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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)

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

medium

Type: Medium

Description: Medium in the component

Used in Components (22)

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	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