Double-Acting Actuator (G)
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Double-acting linear actuator in the gas network.
Description
Block Double-Acting Actuator (G) simulates an actuator that converts the pressure drop between two chambers into piston movement. The movement of the piston is controlled by the differential pressure on both sides of the plate separating the chambers of the block. The limits of piston travel are modelled by one of the hard stop models.
The figure shows the main components of the actuator. Ports A and B represent the gas inlets. Port C is associated with the actuator body, port R is associated with the piston, and it returns the piston velocity. The piston position is calculated internally and transferred to port p.
The HA and HB ports are thermal interfaces between each gas chamber and the environment. The moving piston is adiabatic.
Displacement
The piston displacement is determined by the displacement of port R relative to port C. The value of parameters Mechanical orientation determines the direction of piston displacement. The piston displacement is neutral (equal to 0) when the volume of the chamber A is equal to . Dead volume in chamber A.
The direction of piston movement depends on the parameters Mechanical orientation. If the value is set to Pressure at A causes positive displacement of R relative to C, the piston movement is positive with respect to the actuator body when the gauge pressure at port A is positive. The direction of movement is reversed when set to . Pressure at A causes negative displacement of R relative to C.
Rigid Restrictor Model
A set of rigid stops limits the range of motion of the piston. This block uses an implementation of the block Translational Hard Stop, in which the rigid stops are treated as spring-damping systems. The spring stiffness coefficient determines the restoring component of the contact force of the rigid stop and the damping coefficient determines the dissipating component.
The rigid stops are located at the distal ends of the piston stroke. If the mechanical orientation is positive, the lower hard stop is at , and the upper hard stop is at . If the mechanical orientation is negative, the lower hard stop is at , and the upper hard stop is at .
Ports
Conserving
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A
—
inlet for gas flow into the chamber A
gas
Details
Port corresponding to the gas inlet to the A chamber.
| Program usage name |
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B
—
inlet for gas flow into the chamber B
gas
Details
Port corresponding to the gas inlet to chamber B.
| Program usage name |
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R
—
actuator piston
translational mechanics
Details
A mechanical progressive port corresponding to the actuator piston.
| Program usage name |
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C
—
actuator housing
translational mechanics
Details
Mechanical progressive port corresponding to the actuator housing.
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HA
—
heat associated with the chamber A
`heat
Details
Thermal non-directional port associated with chamber A.
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HB
—
heat associated with the chamber B
`heat
Details
Thermal non-directional port associated with chamber B.
| Program usage name |
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Output
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p
—
piston position
scalar
Details
Piston position in m.
| Data types |
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| Complex numbers support |
No |
Parameters
Actuator
# Same fluid on both sides — whether the same fluid is modelled in both chambers of the unit
Details
Whether the same fluid is modelled on both sides of the block. If the parameters are checked, the fluid properties are propagated through the block. If unchecked, the chambers in the block are connected to isolated networks of fluids with different properties.
| Default value |
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| Program usage name |
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| Evaluatable |
No |
#
Mechanical orientation —
piston travel direction
Pressure at A causes positive displacement of R relative to C | Pressure at A causes negative displacement of R relative to C
Details
Defines the direction of piston movement. Options for selection:
-
Pressure at A causes positive displacement of R relative to C- the piston movement is positive if the volume of gas in port A increases. This corresponds to the movement of the rod out of the cylinder. -
Pressure at A causes negative displacement of R relative to C- the piston movement is negative if the gas volume in port A increases. This corresponds to the rod moving into the cylinder.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
No |
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Piston cross-sectional area in chamber A —
cross-sectional area of the chamber piston rod A
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Details
Cross-sectional area of the piston rod on the chamber side A.
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Piston cross-sectional area in chamber B —
cross-sectional area of the chamber piston rod B
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Details
Cross-sectional area of the piston rod on the chamber side B.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Piston stroke —
piston stroke
m | cm | ft | in | km | mi | mm | um | yd
Details
Maximum possible piston travel.
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Dead volume in chamber A —
volume of gas in the chamber A, at which the piston movement is equal to 0
l | gal | igal | m^3 | cm^3 | ft^3 | in^3 | km^3 | mi^3 | mm^3 | um^3 | yd^3 | N*m/Pa | N*m/bar | lbf*ft/psi | ft*lbf/psi
Details
Volume of gas in chamber A at piston movement value `0'. This gas volume corresponds to the position of the piston at which it is up against the actuator end cap.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Dead volume in chamber B —
volume of gas in the chamber B, at which the piston movement is 0
l | gal | igal | m^3 | cm^3 | ft^3 | in^3 | km^3 | mi^3 | mm^3 | um^3 | yd^3 | N*m/Pa | N*m/bar | lbf*ft/psi | ft*lbf/psi
Details
Volume of gas in chamber B at piston movement value `0'. This gas volume corresponds to the position of the piston at which it is up against the actuator end cap.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Cross-sectional area at port A —
cross-sectional area of the port A
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Details
Cross-sectional area at the inlet.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Cross-sectional area at port B —
cross-sectional area of the port B
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Details
Cross-sectional area at the outlet.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Environment pressure specification —
method of setting the ambient pressure
Atmospheric pressure | Specified pressure
Details
Method of setting the ambient pressure. Variant Atmospheric pressure sets the ambient pressure to 0.101325 MPa.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
No |
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Environment pressure —
ambient pressure
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
User-defined ambient pressure.
Dependencies
To use this parameter, set the parameters to Environment pressure specification value Specified pressure.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
Hard Stop
#
Hard-stop model —
selecting the model of the hard stop
Stiffness and damping applied smoothly through transition region, damped rebound | Full stiffness and damping applied at bounds, undamped rebound | Full stiffness and damping applied at bounds, damped rebound
Details
Selects the model for the force acting on the piston when it is at the end positions. See block for more information Translational Hard Stop
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
No |
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Hard-stop stiffness coefficient —
stiffness factor
N/m | lbf/ft | lbf/in
Details
Piston stiffness coefficient.
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Hard-stop damping coefficient —
damping factor
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Details
Piston damping factor.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Transition region —
range of action of the rigid stop model
m | cm | ft | in | km | mi | mm | um | yd
Details
The operating range of the hard stop. Outside of this range, the piston end positions are not applied. Hard-stop model is not applied and no additional force from the stop is applied to the piston.
Dependencies
To use this parameter, set parameter Hard-stop model value Stiffness and damping applied smoothly through transition region, damped rebound.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
Initial Conditions
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Initial piston displacement from chamber A cap —
initial position of the piston relative to the chamber cover A
m | cm | ft | in | km | mi | mm | um | yd
Details
Piston position relative to the chamber lid A at the beginning of the simulation.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Initial gas pressure in chamber A —
initial gas pressure in the chamber A
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
Initial gas pressure in chamber A.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Initial gas pressure in chamber B —
initial gas pressure in the chamber B
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
Initial gas pressure in chamber B.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Initial gas temperature in chamber A —
initial gas temperature in the chamber A
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Details
Initial gas temperature in chamber A.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Initial gas temperature in chamber B —
initial gas temperature in the chamber B
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Details
Initial gas temperature in chamber B.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |