modelJunctionY
Extends from Interfaces.partialJunctionY.
Information
This component models a Y-shaped Junction. It computes the pressure loss of the fluid depending on the massflow rate or the massflow rate depending on a given pressure difference, some medium properties and the geometry of the Junction. In addition, the thermodynamic state resulting from mixing of the two fluid flow of possibly differnt states is determined. It is not possible to mix different media models. The component is valid for compressible calculation of one phase media and branching angles from 15°-90°. This model is a junction component only. Therfore flows contrary to the intended flow direction immediatly mean inccorect results and can lead to the model crashing. The model is used best with two given mass flow rates, one pressure boundary and steady state or slowly changing buondary conditions. If two pressure boundaries are used, be careful to prevent back flow into the component.
The Y-Junction component is extending the partial model partialJunctionY implementing the common flow balances for fluid merging components. For the pressure loss calculation the functions dp_SplitterWyeType1_DP and dp_JunctionWyeType2_DP are used depending on the users geometry input. See their documentation for a detailed description on the pressure loss calculation an figuers containing pressure loss coefficieint charts.
PLEASE NOTE: Those functions are based on the formulas and data provided in "Handbook of Hydraulic Resistance" by Idel'chik (1960). Be aware that there the book has been updated since then. Those functions calculate and feed back the pressure loss at each channel as well as the pressure loss coefficient with respect to the velocity in the common channel (outlet section). For more information on the pressure loss function click here.
The different types of splitter geometry are defined as described in Idelchik (1960) where:
- Type I: Fb + Fs > Fc and Fc = Fs "straight pipe with attached pipe branch"
- Type II: Fb + Fs = Fc "two smaller branches merging into a straight pipe, whereby the total inlet and outlet area remains the same"
Sketches of both splitter types are shown in Fig. 1. (Currently not yet available)
[P. Jordan; HTWG Konstanz; 01/24]
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Velocity | eps | Modelica.Constants.eps | To avoid division by zero |
| Boolean | assumeConstantDensity | true | = true, if incompressibility is assumed (use '= false' for Ma > 0.3) |
| SI.Area | A_out | if Y_type1 then A_straight else A_straight + A_branching | (Common) outlet cross-sectional area |
| SI.Area | A_straight | pi/4*d_straight^2 | Straight inlet cross-sectional area |
| SI.Area | A_branching | pi/4*d_branching^2 | Branching inlet cross-sectional area |
| Real | alpha_deg | alpha*180/pi | Branching angle (in deg) |
| Geometry | |||
| SI.Length | d_straight | Straight inlet diameter | |
| SI.Length | d_branching | Branching inlet diameter | |
| SI.Angle | alpha | Branching angle | |
| Boolean | Y_type1 | true | = true, if A_out = A_straight, (= false, if A_out = A_straight + A_branching) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Pressure | DP_straight | Pressure loss in straight pipe (-dp_straight) | |
| SI.Pressure | DP_branching | Pressure loss in branching pipe (-dp_branching) | |
| Internal.Types.PressureLossCoefficient | zeta_straight | Pressure loss coefficient of straight pipe | |
| Internal.Types.PressureLossCoefficient | zeta_branching | Pressure loss coefficient of branching pipe | |
| Modelica.Blocks.Tables.CombiTable1Ds | A | ||
| Real | A_rel_bc | A_branching/A_out | Area ratio branch/ (common) outlet |
| Medium.Density | rho_straight | Medium.density(inlet_straight.state) | Density straight inlet |
| Medium.Density | rho_branching | Medium.density(inlet_branching.state) | Density branching inlet |
| Medium.Density | rho_out | if assumeConstantDensity then (rho_straight + rho_branching)/2 else Medium.density(outlet.state) | Outlet density |
| Real | Q_rel_bc | ||
| Modelica.Blocks.Tables.CombiTable2Dv | K_b1 | ||
| Modelica.Blocks.Tables.CombiTable2Dv | K_s1 |