Engee documentation

Rotational Mechanical Converter (TL)

Interface between conductive fluid and mechanical rotational networks.

rotational mechanical converter (tl)

Description

The Rotational Mechanical Converter unit represents the interface between a thermally conductive fluid network and a mechanical rotational network.

The block converts thermal liquid pressure into mechanical torque and vice versa. It can be used as a basic unit for rotary drives.

In the converter, the volume of the fluid is changed and its temperature change is calculated by taking into account the heat capacity of this volume.

Conservation of mass

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

динамическаясжимаемостьжидкостиотключенадинамическаясжимаемостьжидкостивключена

where:

  • - is the mass flow rate of fluid entering the transducer through port A;

  • - mechanical orientation of the transducer (1 if increasing fluid pressure causes a positive displacement of R relative to C, -1 if increasing fluid pressure causes a negative displacement of R relative to C);

  • - fluid density;

  • - transducer displacement;

  • - angular velocity of rotation of the transducer;

  • - volume of liquid inside the transducer;

  • - bulk modulus of elasticity of the liquid inside the transducer;

  • - coefficient of thermal expansion of the liquid;

  • - pressure of liquid inside the converter;

  • - temperature of liquid inside the converter.

The rotation angle 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 parts if the liquid volume is equal to the value of the Dead Volume parameters.

Storing the pulse

The equation for conservation of momentum in a mechanical converter:

,

where:

  • - is the torque caused by the fluid pressure on the moving elements of the converter;

  • - atmospheric pressure.

Conservation of energy

The equation of conservation of energy in a mechanical converter:

,

where:

  • - is the internal energy of the fluid in the converter;

  • - the total energy flow of the fluid entering inside the mechanical converter through port A;

  • - heat flux through port H.

Assumptions and limitations

  • The converter walls do not deform independently of internal pressure and temperature.

  • The inverter does not contain any mechanical hard limiters. Use the Rotational Hard Stop block to enable hard limiters.

  • The hydraulic resistance between the inlet and the inside of the inverter can be neglected.

  • The thermal resistance between the thermal port and the inside of the inverter can be neglected.

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

Ports

Non-directional

A - transmitter input port
thermal liquid

Thermal liquid port, corresponds to the inlet to the transmitter.

H - heat port
heat

A port related to the temperature of the fluid inside the inverter.

R - shaft

Mechanical rotary port, corresponds to the inverter shaft.

C - housing
`rotational mechanics

Mechanical rotary port, corresponds to the inverter housing.

Parameters

Main

Mechanical orientation - orientation of the transducer
Pressure at A causes positive rotation of R relative to C (by default) | `Pressure at A causes negative rotation of R relative to C `

Parameters defines the direction of rotation of the shaft R relative to the housing C depending on the change of the internal volume of the inverter.

  • `Pressure at A causes positive rotation of R relative to C' - an increase in fluid volume causes positive rotation of port R relative to port C.

  • `Pressure at A causes negative rotation of R relative to C' - an increase in fluid volume causes negative rotation of port R relative to port C.

Initial interface rotation - initial offset of port R relative to port C
0 (By default)

The value 0 corresponds to the initial fluid volume equal to Dead volume .

Dependencies

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

Interface volume displacement - volume of fluid displaced per rotation
1.2e-4 m^3/rad (by default).

Volume of displaced/infeeding liquid per one rotation of the mechanical converter shaft.

Dead volume - volume of liquid in the transducer at which the shaft rotation angle is equal to zero
0.1e-5 m^3 (by default)

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

Cross-sectional area at port A - cross-sectional area at the inlet to the transmitter
0.01 m^2 (by default).

Cross-sectional area of the inlet cross-sectional area of the transmitter.

Environment pressure specification - method for determining the ambient pressure

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

  • Specified pressure - the pressure value specified in the Environment pressure parameters is used.

Environment pressure - pressure of the medium in the external part of the transmitter
`0.101325 MPa (by default).

The pressure outside the transmitter acting against the fluid pressure in the transmitter volume. A value of 0 indicates that the transmitter is operating in vacuum.

Dependencies

Used when the Environment pressure specification parameters are set to Specified pressure.

Effects and Initial Conditions

Fluid dynamic compressibility - modelling of fluid dynamic compressibility
On (By default) | Off

  • If checked, fluid dynamic compressibility is taken into account.

Dynamic compressibility determines the dependence of fluid density on pressure and temperature, affecting transients in the system on small time intervals.

Initial liquid pressure - pressure of liquid at zero moment of time
0.101325 MPa (by default)

Liquid pressure in the transmitter at the start of the simulation.

Dependencies

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

Initial liquid temperature is the liquid temperature at zero point in time
`293.15 K (by default).

The temperature of the liquid in the transmitter at the start of the simulation.