Translational Mechanical Converter (TL)

The interface between the networks of heat-conducting fluid and translational mechanics.

blockType: AcausalFoundation.ThermalLiquid.Elements.TranslationalMechanicalConverter

Path in the library:

/Physical Modeling/Fundamental/Thermal Liquid/Elements/Translational Mechanical Converter (TL)

Description

Block Translational Mechanical Converter (TL) simulates the interface between a network of thermally conductive fluid and a network of translational motion mechanics. The block converts the pressure of the heat-conducting liquid into mechanical force and vice versa. The unit can be used as the main component for linear actuators.

The converter has a variable volume of liquid, and the change in its temperature is calculated taking into account the heat capacity of this volume. If the Fluid dynamic compressibility checkbox is selected, the pressure will also depend on the dynamic compressibility of the fluid. The Mechanical orientation parameter allows you to determine the direction of movement of port R relative to port C with increasing pressure.

Port A is the port of a thermally conductive liquid corresponding to the input section of the converter. The H port is a thermal port that reflects the temperature of the liquid inside the converter. Ports R and C are mechanical translational motion ports connected to the movable part (rod) and the converter housing, respectively.

Conservation of mass

The mass conservation equation for a mechanical transducer has the form:

where:

— the mass flow rate of the liquid in the converter through port A.
— mechanical orientation of the transducer (1 if an increase in fluid pressure causes a positive displacement of R relative to C, -1 if an increase in fluid pressure causes a negative displacement of R relative to C).
— the density of the liquid in the converter.
— the cross-sectional area of the working surface of the transducer rod.
— the speed of movement of the transducer rod.
— the volume of liquid inside the converter.
— the volumetric modulus of elasticity of the liquid in the transducer housing.
— the coefficient of thermal expansion of the liquid.
— the pressure of the liquid inside the transducer housing.
— the temperature of the liquid inside the transducer housing.

In the block, the stem displacement is calculated from the relative port speeds according to the block equations. The position of the stem is zero when the volume of the liquid is equal to the unused volume (the value of the Dead Volume parameter). The direction of the rod action is determined depending on the value of the parameter Mechanical orientation:

If Pressure at A causes positive displacement of R relative to C, the displacement of the stem increases when the volume of the liquid increases compared to the unused volume.
If Pressure at A causes negative displacement of R relative to C, the displacement of the stem decreases when the volume of the liquid increases compared to the unused volume.

Conservation of momentum

The momentum conservation equation for a mechanical transducer has the form:

where:

— the force with which the liquid acts on the transducer rod.
— atmospheric pressure.

Energy conservation

The energy conservation equation for a mechanical converter has the form:

where:

— internal energy of the liquid.
— full power flow through port A.
— the amount of heat flow through the port H.

Assumptions and limitations

The walls of the converter are absolutely rigid. They do not deform due to internal pressure and temperature.
The converter does not contain any mechanical rigid limiters. To add hard limits, use the block Translational Hard Stop.
The hydraulic flow resistance between the inlet port and the inside of the converter is negligible.
The thermal resistance between the thermal port and the inside of the converter is negligible.
The kinetic energy of the liquid in the converter is negligible.

Ports

Non-directional

A — input port to the pass converter:q[<br>] heat-conducting liquid

The port of the heat-conducting liquid corresponds to the input to the converter.

H is the temperature of the liquid in the pass converter:q[<br>] warm

The thermal port associated with the temperature of the liquid in the converter.

R — stock
translational mechanics

Mechanical translational port, corresponds to the stem of the converter.

C — housing
translational mechanics

Mechanical translational port, corresponds to the converter housing.

Parameters

Main

Mechanical orientation — orientation of the pass converter:q[<br>]

Pressure at A causes positive displacement of R relative to C (default)|Pressure at A causes negative displacement of R relative to C

The parameter sets the direction of movement of the rod depending on the change in the volume of the liquid:

Pressure at A causes positive displacement of R relative to C — an increase in the volume of liquid leads to a positive displacement of port R relative to port C.
Pressure at A causes negative displacement of R relative to C — an increase in the volume of liquid leads to a negative displacement of port R relative to port C.

Initial interface displacement — initial position of port R relative to port C
m (default)

The linear displacement 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 displacement of R relative to C, then the parameter value must be greater than or equal to 0.
If Mechanical orientation is important Pressure at A causes negative displacement of R relative to C, then the parameter value must be less than or equal to 0.

Interface cross-sectional area is the cross-sectional area of the internal channel of the transducer, or the working area of the rod on which the liquid exerts pressure, creating a force
0.01 m^2 (default)

The area on which the liquid exerts pressure, creating a translational force.

Dead volume - the volume of liquid at which the stem position is 0
1e−5 m^3 (default)

The volume of liquid at which the position of the stem is equal to 0.

Environment pressure specification — method for determining ambient pressure
Atmospheric pressure (by default) | Specified pressure

Defines a method for determining ambient pressure:

Atmospheric pressure — the atmospheric pressure set in the Thermal Liquid Settings (TL) units is used or Thermal Liquid Properties (TL) connected to the circuit.
Specified pressure — the pressure value specified in the Environment pressure parameter is used.

Environment pressure — the pressure of the medium in the external part of 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

Used if the Environment pressure specification parameter is set to Specified pressure.

Effects and Initial Conditions

Fluid dynamic compressibility — simulation of dynamic compressibility of a liquid
enabled (by default) | turned off

Select the checkbox to enable dynamic compressibility accounting. In the simulation process, dynamic compressibility determines the dependence of liquid density on pressure and temperature, and affects transient processes in the system in small time intervals.

Initial liquid pressure - the initial value of the liquid pressure
0.101325 MPa (default)

The pressure of the liquid in the transducer at the beginning of the simulation.

Dependencies

To enable this option, select the Fluid dynamic compressibility checkbox.

Initial liquid temperature - the initial temperature of the liquid
293.15 K (default)

The temperature of the liquid in the converter at the beginning of the simulation.