Engee documentation

Rotational Mechanical Converter (TL)

The interface between heat-conducting liquid and mechanical rotary networks.

blockType: AcausalFoundation.ThermalLiquid.Elements.RotationalMechanicalConverter

rotational mechanical converter (tl)

Path in the library:

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

Description

The Rotary Mechanical Converter block represents the interface between a thermally conductive liquid network and a mechanical rotary network.

In the block, the pressure of the heat-conducting liquid is converted into mechanical torque and vice versa. It can be used as the main unit for rotary drives.

In the converter, the volume of the liquid is variable and the change in its temperature is calculated taking into account the heat capacity of this volume.

Conservation of mass

The equation of conservation of mass inside a mechanical transducer has the form:

динамическаясжимаемостьжидкостиотключенадинамическаясжимаемостьжидкостивключена

where:

  • — the mass flow rate of the liquid entering the converter through port A;

  • — mechanical orientation of the transducer (1 if an increase in liquid pressure causes a positive displacement of R relative to C, -1 if an increase in liquid pressure causes a negative displacement of R relative to C);

  • — density of the liquid;

  • — displacement of the converter;

  • — angular rotation speed of the converter;

  • — the volume of liquid inside the converter;

  • — volumetric modulus of elasticity of the liquid inside the transducer;

  • — coefficient of thermal expansion of the liquid;

  • — the pressure of the liquid inside the converter;

  • — the temperature of the liquid inside the converter.

The angle of rotation of the moving parts of the converter in the block is calculated based on the relative angular velocities of the ports in accordance with the block equations. There is no rotation of the moving elements if the volume of the liquid is equal to the value of the Dead Volume parameter.

Conservation of momentum

The equation of conservation of momentum in a mechanical converter:

,

where:

  • — the torque caused by the pressure of the liquid on the moving elements of the converter;

  • — atmospheric pressure.

Energy conservation

The equation of conservation of energy in a mechanical converter:

,

where:

  • — internal energy of the liquid in the converter;

  • — the flow of the total energy of the liquid entering the mechanical converter through port A;

  • — heat flow through port H.

Assumptions and limitations

  • The walls of the transducer do not deform regardless of the internal pressure and temperature.

  • The converter does not contain any mechanical rigid limiters. To turn on the hard limiters, use the block Rotational Hard Stop.

  • The hydraulic resistance between the input and the inside of the transducer can be ignored.

  • The thermal resistance between the thermal port and the inside of the converter can be ignored.

  • The kinetic energy of the liquid in the converter can be neglected.

Ports

Non-directional

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

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

H – thermal port
warm

The port connected to the temperature of the liquid inside the converter.

R – shaft

Mechanical rotary port, corresponds to the converter shaft.

C — housing
rotational mechanics

Mechanical rotary port, corresponds to the converter housing.

Parameters

Main

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 to C

The parameter determines the direction of rotation of the shaft R relative to the housing C depending on the change in the internal volume of the converter.

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

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

Initial interface rotation – the initial offset of port R relative to port C
0 (default)

Meaning 0 corresponds to the initial volume of the liquid equal to Dead volume .

Dependencies

  • The parameter value must be greater than or equal to if Mechanical orientation matches the value Pressure at A causes positive rotation of R relative to C.

  • The parameter value must be less than or equal to zero if Mechanical orientation matches the value Pressure at A causes negative rotation of R relative to C.

Interface volume displacement – volume of displaced liquid per rotation of the PC:q[<br>] 1.2e-4 m^3/rad (default)

The volume of the displaced/ incoming liquid per revolution of the shaft of the mechanical converter.

Dead volume — the volume of liquid in the converter at which the angle of rotation of the shaft is zero
0.1e-5 m^3 (default)

The volume of liquid in the converter at which the angle of rotation of the shaft is zero.

Cross-sectional area at port A — the cross-sectional area at the entrance to the pass converter:q[<br>] 0.01 m^2 (default)

The cross-sectional area of the input section of the converter.

Environment pressure specification — a method for determining environmental pressure

  • Atmospheric pressure — the atmospheric pressure specified in the Thermal Liquid Settings (TL) block is used or Thermal Liquid Properties (TL).

  • 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 of the liquid in the volume of the transducer. Meaning 0 This means that the converter operates in a vacuum.

Dependencies

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

Effects and Initial Conditions

Fluid dynamic compressibility — simulation of dynamic compressibility of liquids as:q[<br>] enabled (by default) | turned off

  • If this option is selected, the dynamic compressibility of the liquid is taken into account.

Dynamic compressibility determines the dependence of liquid density on pressure and temperature, affecting transient processes in the system over short time intervals.

Initial liquid pressure — the pressure of the liquid at zero time, as:q[<br>] 0.101325 MPa (default)

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

Dependencies

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

Initial liquid temperature — the temperature of the liquid at time zero
293.15 K (default)

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