Air Detailed Flow
Detailed flow calculation of Air
The Air Detailed Flow component models a flow calculation which is for Laminar and Turbulent for the lumped thermal fluid simulation of Air. This component calculates mainly pressure difference and mass flow rate.
The calculation is changed based on parameter values of Type of pipe, and Dynamics of mass in the Air Settings component.
The definition of Inner hydraulic diameter and Flow area, Geometrical coefficient for laminar flow are explained in the following:
Type of pipe = General
Inner hydraulic diameter is defined with:
Flow area is defined with:
Geometrical coefficient for Laminar flow is defined with:
Geo__act=geo__inExternal input of Geometrical coefficient=trueGeoothers
Type of pipe = Circular
Geometrical coefficient for laminar flow is defined with:
Type of pipe = Rectangular
(*) `MapleSim.Interpolate1D` is the function of Lookup table of 1D.
(*) data is specified with:
- If data_source = inline, parameter table__rect.
- If data_source = attachment, an attached file (.csv and .xls, .xlsx) is used
- If data_source = file, need to specify the path of file (.csv and .xls, .xlsx).
Reynolds number is calculated with:
The friction factor of flow is calculated with:
(*) The above function `HeatTransfer.Functions.lambda_Re` is to calculated friction factor for Laminar and Turbulent flow.
The fundamental implementation is based on the following equations. Especially, the equation of Turbulent flow is Swamee and Jain's approximation .
(Reference) Detailed implementation of Friction factor calculation
Friction factor of Laminar flow is calculated with:
And, Turbulent flow's friction factor is defined with (Swamee and Jain's approximation):
Intermittency is defined with:
So, the friction factor is calculated with:
The following plot is Reynolds number vs Friction factor, and roughnessD__h_act=0.001, IF__speed=0.007, Re__CoT=3500, Geo__act=1.
The definition of Flow calculation is the following and :
Dynamics of mass = Static
Pressure difference is calculated with Darcy–Weisbach equation:
Dynamics of mass = Dynamic
In theory, Mass flow rate is calculated with Darcy–Weisbach equation:
In the Heat Transfer Library, the following equation is used to resolve difficulties of the numerical calculation:
(*) `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.
Definitions related to Mass flow rate and pressure :
Density is calculated with:
If Fidelity of properties = Constant, properties are calculated with:
(*) Regarding the value of properties for Constant, see more details in Air Settings.
If Fidelity of properties = Ideal Gas (NASA Polynomial), properties are calculated with:
(*) The properties are defined with NASA polynomials and coefficients, see more details in Air Settings.
Port's variables are defined with:
 : Swamee P.K., Jain A.K. (1976): Explicit equations for pipe-flow problems. Proc. ASCE, J.Hydraul. Div., 102 (HY5), pp. 657-664.
Mass flow rate
Velocity of flow
Inner hydraulic diameter used for Fluid simulation
Flow area used for Fluid simulation
Geometrical coefficient used for Fluid simulation
Reynolds number for Friction factor calculation
Targeted Reynolds number for Friction factor calculation
Friction factor for Laminar flow
Friction factor for Turbulent flow
Intermittency factor to calculate Transition zone
Density at port_a
Density at port_b
Dynamic viscosity at port_a
Dynamic viscosity at port_b
if External input of Geometrical coefficient = false
Geometrical coefficient input
Specify a component of Air simulation settings
Select pipe type
- Circular pipe
- Rectangular pipe
Internal hydraulic diameter if Type of pipe is General or Circular.
Horizontal length only if Type of pipe = Rectangular.
Vertical length only if Type of pipe = Rectangular.
Flow area only if Type of pipe = General.
Absolute roughness of pipe, with a default for a smooth steel pipe
External input ofGeometricalcoefficient
If true, Geometrical coefficient is defined by the input. And, if Type of pipe = Rectangular, this parameter is valid.
Geometrical coefficient for Laminar flow only if Type of pipe = General and External input of Geometrical coefficient = false.
See Data Source Options section above.
Geometrical coefficient for Rectangular pipe, if data source__rect = inline.
 :Volume flow rate
 :Pressure difference
Geometrical coefficient for Rectangular pipe, if data source__rect =file or attachment. You can specify data by using an attached file or specifying the path of file (.csv and .xls, .xlsx)
Determines which columns of the data table will be used to interpolate.
For example, in an Excel spreadsheet, column A corresponds with 1, column B corresponds with 2, and so on.
Number of rows that are skipped from the top of the data table.
Table points are linearly interpolated
Determines whether the data points will be interpolated linearly or with a cubic spline.
Approximation of function for |dp| <= dp_small
Sharpness of approximation for sqrt(dp) and sqrt(rho * dp)
Time constant for Reynolds number calculation
Reynolds number of the center of Transition zone
Changing rate of Intermittency factor
Heat Transfer Library Overview
Air Shapes Overview
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