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# Translational Mechanical Converter (TL)

Interface between liquid and translational mechanical subsystems

## Library

Thermal Liquid/Elements

## Description

The Translational Mechanical Converter (TL) block represents the liquid side of a translational mechanical interface. This interface converts liquid pressure into force and vice versa. The output force acts in a single direction, set using a Mechanical orientation parameter.

The translational mechanical interface contains no hard stops. To include hard stops, use the Simscape™ Translational Hard Stop block. A model of a translational hydraulic actuator, for example, requires both blocks.

Port A is a thermal liquid conserving port corresponding to the converter inlet. Liquid pressure in the converter equals that at port A. Port Q is a thermal conserving port for modeling heat exchange between the converter liquid and the converter housing. Liquid temperature in the converter equals that at port Q.

The block models the dynamic evolution of temperature in the converter. The block can also model dynamic compressibility effects in the enclosed liquid. The following equations govern the dynamic behavior of liquid at the interface:

where

 A Cross-sectional area of the interface ε Mechanical orientation (1 for Positive, -1 for Negative) F Force the liquid exerts on the interface V Liquid volume in the converter vA Liquid velocity into the converter at port A vinterface Interface velocity (positive for converter expansion, negative for converter contraction) pint Liquid pressure in the converter Tint Liquid temperature in the converter Mass flow rate into the converter at port A βint Liquid bulk modulus in the converter αint Liquid coefficient of thermal expansion in the converter uint Liquid internal energy in the converter ρint Liquid density in the converter ϕA, ϕQ Thermal fluxes into the converter at ports A and Q

The liquid velocity follows from the mass flow rate into the converter:

where ρA,u is the upwind liquid density at port A.

To view the block source code, at the MATLAB® command line enter:

```edit <matlabroot>\toolbox\physmod\simscape\library\m\
+foundation\+thermal_liquid\+elements\<converter>.ssc```

Replace <matlabroot> with the output of the matlabroot command, and <converter> with the compressibility configuration mode using this syntax:

• translational_converter_dynamic_compressibility for the code corresponding to fluid dynamic compressibility ‘On'

• translational_converter_steady_compressibility for the code corresponding to fluid dynamic compressibility ‘Off'

## Assumptions and Limitations

• Converter walls are not compliant. They cannot deform, regardless of internal pressure and temperature.

• The converter contains no mechanical hard stop.

## Dialog Box and Parameters

Mechanical orientation

Select the relative orientation of the converter with respect to the thermal liquid system. The relative orientation determines the translation direction associated with positive flow into the converter. That direction is positive if the mechanical orientation of the converter is positive. It is negative if the mechanical orientation of the converter is negative. The default setting is Positive.

Interface cross-sectional area

Enter the cross-sectional area of the converter interface. This is the area the liquid must push to generate a force. The default value is 0.01 m^2.

Interface initial extension

Enter the offset distance between the translating converter interface and the converter cap at time zero. The default value is 0.

Enter the liquid volume remaining in the converter at a zero offset distance. The default value is 1e-5 m^3.

Fluid initial temperature

Enter the liquid temperature in the converter at time zero. The default value is 293.15 K.

Fluid dynamic compressibility

Select whether to include the effect of fluid dynamic compressibility on the transient response of the converter model. Selecting On exposes an additional parameter. The default setting is Off.

Fluid initial pressure

Enter the liquid pressure in the converter at time zero. This parameter is visible only if Fluid dynamic compressibility is On. The default value is 1 atm.

## Ports

This block has the following ports.

 A Thermal liquid conserving port Q Thermal conserving port R Translational mechanical conserving port associated with the moving interface C Translational mechanical conserving port associated with the converter casing