Rotational Mechanical Converter (IL)
The interface between isothermal liquid and mechanical rotational networks.
blockType: AcausalFoundation.IsothermalLiquid.Elements.RotationalMechanicalConverter
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Description
Block Rotational Mechanical Converter (IL) It is an interface between an isothermal liquid network and a mechanical rotary network. The unit converts fluid pressure into torque and vice versa. It can be used as a base for rotating hydraulic drives.
The volume of liquid in the converter changes during operation. If the Fluid dynamic compressibility parameter is enabled, the pressure is calculated depending on the compressibility of the liquid (dynamic compressibility of the liquid).
The Mechanical orientation parameter determines whether an increase in fluid volume leads to a positive or negative rotation of port R relative to port C.
Port A is the isothermal fluid port corresponding to the input of the transducer. Ports R and C are mechanical rotary ports corresponding to the shaft and housing respectively.
Conservation of mass
The mass conservation equations for the converter have the form:
,
,
,
,
where:
-
— mass flow through port A.
-
— mechanical orientation of the transducer (
1if an increase in fluid pressure causes a positive rotation of R relative to C,−1if an increase in fluid pressure causes a negative rotation of R relative to C). -
— the density of the liquid inside the transducer.
-
— volumetric modulus of elasticity of a liquid.
-
— volumetric displacement of the transducer, that is, the volume of liquid required to rotate the shaft per unit angle.
-
— the angular speed of rotation of the converter shaft.
-
and * — the angular velocities of ports R and C, respectively.
-
— the angle of rotation of the converter shaft.
-
— the volume of liquid inside the converter.
-
— the volume of liquid at which the angle of rotation of the shaft is equal to
0. -
— pressure inside the transducer.
The angle of rotation of the shaft is zero when the volume of the liquid is . Depending on the value of the parameter Mechanical orientation:
-
If the Mechanical orientation parameter is set to
Pressure at A causes positive rotation of R relative to C, then the angle of rotation of the shaft when the volume of liquid increases in comparison with . -
If the Mechanical orientation parameter is set to
Pressure at A causes negative rotation of R relative to C, then the angle of rotation of the shaft decreases when the volume of the liquid increases compared to .
The equations used to calculate the density and volume modulus of elasticity of a liquid mixture depend on the chosen model of the isothermal fluid.
Momentum Balance
The equation of conservation of momentum in the volume of a mechanical transducer has the form:
,
where:
-
— the torque on the converter shaft.
-
— ambient pressure.
Assumptions and limitations
-
The walls of the transducer are ideally rigid.
-
The converter does not contain any mechanical rigid limiters. To turn on the hard limiters, use the block Rotational Hard Stop.
-
The flow resistance between the input and the inside of the converter is negligible.
-
The kinetic energy of the liquid in the converter is negligible.
Ports
Non-directional
A — inlet of the pass converter:q[<br>] isothermal liquid
The isothermal fluid port corresponds to the input of the transducer.
R — shaft pass:Q[<br>] rotational mechanics
Mechanical rotary port, corresponds to the converter shaft.
C — housing
rotational mechanics
The mechanical rotary port corresponds to the converter housing.
Parameters
Mechanical orientation — orientation of the pass converter:q[<br>] Pressure at A causes positive rotation of R relative to C (default) | Pressure at A causes negative rotation of R relative
Sets the direction of rotation of the shaft relative to the liquid pressure:
-
Pressure at A causes positive rotation of R relative to C— an increase in liquid pressure causes the port R to rotate relative to the port C in a positive direction. -
Pressure at A causes negative rotation of R relative to C— an increase in liquid pressure causes the port R to rotate relative to the port C in a negative direction.
Initial interface rotation — the initial angular position of port R relative to port C at the beginning of the simulation
0.0 (default)
The angular position of port R relative to port C at the beginning of the simulation. Meaning 0 corresponds to the initial volume of the liquid equal to Dead volume.
Dependencies
-
If Mechanical orientation is important
Pressure at A causes positive rotation of R relative to C, the parameter value must be greater than or equal to0. -
If Mechanical orientation is important
Pressure at A causes negative rotation of R relative to C, the parameter value must be less than or equal to0.
Interface volume displacement — the volume of liquid being moved per unit rotation angle
0.001 m3/rad (default)
The volume of the liquid being moved per unit angle of rotation of the shaft.
Dead volume — the volume of liquid in the converter at which the angle of rotation of the shaft is zero
1e−5 m3 (default)
The volume of liquid in the converter at which the angle of rotation of the shaft is zero.
Environment pressure specification — method for setting ambient pressure
Atmospheric pressure (by default) | Specified pressure
Defines the method of setting the ambient pressure:
-
Atmospheric pressure— atmospheric pressure. -
Specified pressure— the exact value specified in the Environment pressure parameter.
Environment pressure — pressure outside the pass converter:q[<br>] 0.101325 MPa (default)
The pressure outside the transducer acting against the pressure inside. Meaning 0 This means that the converter operates in a vacuum.
Dependencies
Available if the Environment pressure specification parameter is set to Specified pressure.
Fluid dynamic compressibility — determines whether it is necessary to simulate the dynamic compressibility of a liquid
Enabled (by default) | Disabled
Specifies whether the dynamic compressibility of the liquid should be taken into account. Dynamic compressibility makes the density of a liquid dependent on pressure, which affects the transient response of the system on small time scales.
Initial liquid pressure — the pressure of the liquid at the initial moment of time
0.101325 MPa (default)
The pressure of the liquid at the beginning of the simulation.
Dependencies
Used if the Fluid dynamic compressibility parameter is set to Enabled.