Air Flow - MapleSim Help
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Air Flow

Flow calculation of Air

 

Description

Equations

Variables

Connections

Parameters

See Also

Description

The Air Flow component models a generic flow calculation for the lumped thermal fluid simulation of Air. In this component, pressure difference and mass flow rate are calculated.

 

Equations

The calculation is changed based on parameter values of Type of flow and Dynamics of mass in the Air Settings component.

 

Type of flow = Linear and Dynamics of mass = Static

Pressure difference is calculated with:

dp=1Aα__linearmflow

Type of flow = Linear and Dynamics of mass = Dynamic

Mass flow rate is calculated with:

mflow=Aα__lineardp

 

Type of flow = Square root and Dynamics of mass = Static

Pressure difference is calculated with:

dp=1Aα__sqrt2mflow2signmflow

Type of flow = Square root and Dynamics of mass = Dynamic

In theory, Mass flow rate is calculated with:

mflow=Aα__sqrtdp

In the Heat Transfer Library, the following equation is used to resolve difficulties of the numerical calculation:

mflow=Aα__sqrt`HeatTransfer.Functions.regRoot`dp,sharpness

(*) `HeatTransfer.Functions.regRoot` is the same function as `Modelica.Fluid.Utilities.regRoot`. To check the details of the package and view the original documentation, which includes author and copyright information, click here.

 

Type of flow = Darcy-Weisbach and Dynamics of mass = Static

Pressure difference is calculated with:

dp=12λLD__hA2{inStream`port_a.rho`dp0inStream`port_b.rho`othersmflow2signmflow

Type of flow = Darcy-Weisbach and Dynamics of mass = Dynamic

In theory, Mass flow rate is calculated with:

mflow=2D__hA2λL{inStream`port_a.rho`dp0inStream`port_b.rho`othersdp

In the Heat Transfer Library, the following equation is used to resolve difficulties of the numerical calculation:

mflow=2D__hA2λL`HeatTransfer.Functions.regRoot2`dp,dp_small,inStream`port_a.rho`,inStream`port_b.rho`,true,sharpness

(*) `HeatTransfer.Functions.regRoot2` is the same function as `Modelica.Fluid.Utilities.regRoot2`. To check the details of the package and view the original documentation, which includes author and copyright information, click here.

 

Common definitions are the following:

dp=`port_a.p``port_b.p`

v=mflow{inStream`port_a.rho`dp0inStream`port_b.rho`othersA

`port_a.mflow`=mflow

`port_b.mflow`=mflow

`port_a.hflow`=inStream`port_b.hflow`

`port_b.hflow`=inStream`port_a.hflow`

`port_a.rho`=inStream`port_b.rho`

`port_b.rho`=inStream`port_a.rho`

`port_a.T`=inStream`port_b.T`

`port_b.T`=inStream`port_a.T`

 

Variables

Symbol

Units

Description

Modelica ID

dp

Pa

Pressure difference

p

mflow

kgs

Mass flow rate

mflow

v

ms

Velocity of flow

v

Connections

Name

Description

Modelica ID

port__a

Air Port

port_a

port__b

Air Port

port_b

Parameters

Symbol

Default

Units

Description

Modelica ID

Airsimulationsettings 

AirSettings1

Specify a component of Air simulation settings

Settings

Type offlow

Linear

Select Flow calculation type

 - Linear

 - Square root

 - Darcy-Weisbach

TypeOfFlow

α__linear

10

Flow coefficient for Linear type

alpha_lin

α__sqrt

60

Flow coefficient for Square root type

alpha_sqrt

L

0.1

m

Pipe length (Only for Darcy-Weisbach)

L

D__h

0.1

m

Internal hydraulic diameter (Only for Darcy-Weisbach)

Dh

A

Pi400

m2

Flow area

A

λ

0.000015

Friction coefficient for Darcy-Weisbach equation

lambda

dp__small

0.1

Pa

Approximation of function for |dp| <= dp_small

dp_small

sharpness

1.0

Sharpness of approximation for sqrt(dp) and sqrt(rho * dp)

sharpness

See Also

Heat Transfer Library Overview

Air Overview

Air Basic Overview