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Change

Sudden or gradual cross sectional area change in pipe with contraction and enlargement

 

Description

Equations

Variables

Connections

Parameters

Description

The Change component models sudden or gradual changes in the diameter of a pipe and captures both contraction and enlargement within the component.

Equations

The ratio of diameters is calculated as

If

    Loss coefficient of contraction at inlet:

    Loss coefficient of enlargement at outlet:

otherwise,

    Loss coefficient of contraction at inlet:

    Loss coefficient of enlargement at outlet:

The total loss coefficient is defined by using the linear approximation for the transition between contraction and enlargement:

References

[1] : Flow of Fluids Through Valves, Fittings, and Pipes, Crane Valves North America, Technical Paper No. 410M. 1979, p A-26

Variables

Name

Value

Units

Description

Modelica ID

 

Pressure drop from A to B

p

 

Flow rate into port A

q

Connections

Name

Description

Modelica ID

Upstream hydraulic

portA

Downstream hydraulic port

portB

Parameters

General

Name

Default

Units

Description

Modelica ID

Diameter, port_a side

d_a

Diameter, port_b side

d_b

Angle of Contraction/Enlargement

theta

 

Reynolds number at critical flow

ReCr

Pressure difference for transition zone

p_transition

Fluid Parameters

The following parameters, used in the equations, are properties of the Hydraulic System Properties component used in the model.

Name

Units

Description

Modelica ID

Kinematic viscosity of fluid

nu

Density of fluid

rho

Bulk modulus of fluid

El

See Also

Hydraulics Library

Restrictions

 


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