modelJunctionY
Extends from Interfaces.partialJunctionY (Duplicate of JunctionN considering dynamic effects).
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 |
|---|---|---|---|
| String | instanceName (from DropOfCommonsPlus) | getInstanceName() | Instance name |
| Boolean | assumeConstantDensity (from partialJunctionY) | true | = true, if mixture states are determined by mass flow rates |
| SI.Velocity | eps | Modelica.Constants.eps | To avoid division by zero |
| 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) |
| Layout | |||
| Boolean | displayInstanceName (from DropOfCommonsPlus) | dropOfCommons.displayInstanceNames | = true, if instance name is displayed |
| Boolean | displayParameters (from DropOfCommonsPlus) | dropOfCommons.displayParameters | = true, if displaying parameters is enabled |
| Advanced | |||
| SI.MassFlowRate | m_flow_eps (from partialJunctionY) | dropOfCommons.m_flow_reg | Regularization threshold for small mass flows |
| ThermofluidStream.Utilities.Units.Inertance | L (from partialJunctionY) | dropOfCommons.L | Inertance on each Branch of Component |
| 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) |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| ThermofluidStream.Interfaces.Outlet | outlet (from partialJunctionY) | Outlet | |
| ThermofluidStream.Interfaces.Inlet | inlet_straight (from partialJunctionY) | Inlet A | |
| ThermofluidStream.Interfaces.Inlet | inlet_branching (from partialJunctionY) | Inlet B |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Real | w_straight (from partialJunctionY) | Regularized weighting factor for specific enthalpy inlet straight | |
| Real | w_branching (from partialJunctionY) | Regularized weighting factor for specific enthalpy inlet branching | |
| Medium.Density | rho_straight (from partialJunctionY) | Medium.density(inlet_straight.state) | Density at straight inlet |
| Medium.Density | rho_branching (from partialJunctionY) | Medium.density(inlet_branching.state) | Density at branching inlet |
| Medium.Density[2] | rho (from partialJunctionY) | {rho_straight, rho_branching} | Density at inlet [straight branching] |
| Real[2] | w (from partialJunctionY) | {w_straight, w_branching} | Regularized weighting factor for specific enthalpy |
| Medium.AbsolutePressure | p_in_straight (from partialJunctionY) | Medium.pressure(inlet_straight.state) | (steady mass-flow) pressure straight inlet |
| Medium.AbsolutePressure | p_in_branching (from partialJunctionY) | Medium.pressure(inlet_branching.state) | (steady mass-flow) pressure branching inlet |
| Medium.AbsolutePressure | p_straight (from partialJunctionY) | Total pressure straight inlet | |
| Medium.AbsolutePressure | p_branching (from partialJunctionY) | Total pressure branching inlet | |
| Medium.AbsolutePressure[2] | p (from partialJunctionY) | {p_straight, p_branching} | Total pressure inlets [straight branching] |
| SI.Pressure | dq_straight (from partialJunctionY) | Dynamic pressure difference straight inlet - outlet | |
| SI.Pressure | dq_branching (from partialJunctionY) | Dynamic pressure difference straight inlet - outlet | |
| SI.Pressure | dp_straight (from partialJunctionY) | Pressure difference straight inlet - outlet | |
| SI.Pressure | dp_branching (from partialJunctionY) | Pressure difference branching inlet - outlet | |
| SI.Pressure[2] | dp (from partialJunctionY) | {dp_straight, dp_branching} | Pressure differences inlets [straight branching] |
| Medium.SpecificEnthalpy | h_straight (from partialJunctionY) | Medium.specificEnthalpy(inlet_straight.state) | Specific enthapy inlet straight |
| Medium.SpecificEnthalpy | h_branching (from partialJunctionY) | Medium.specificEnthalpy(inlet_branching.state) | Specific enthapy inlet branching |
| Medium.SpecificEnthalpy[2] | h (from partialJunctionY) | {h_straight, h_branching} | Specific enthapy inlets [straight branching] |
| Medium.SpecificEnthalpy | h_mix (from partialJunctionY) | Outlet specific enthalpy | |
| Medium.MassFraction[Medium.nXi,2] | Xi (from partialJunctionY) | Mass factions inlets [straight branching] | |
| Medium.MassFraction[Medium.nXi] | Xi_mix (from partialJunctionY) | Mass fractions outlet | |
| Medium.AbsolutePressure | p_mix (from partialJunctionY) | Outlet (steady mass-flow) pressure | |
| SI.Pressure | r_mix (from partialJunctionY) | Outlet inertial pressure | |
| SI.Velocity | c_straight (from partialJunctionY) | Velocity straight inlet | |
| SI.Velocity | c_branching (from partialJunctionY) | Velocity branching inlet | |
| SI.Velocity | c_mix (from partialJunctionY) | Velocity outlet | |
| Real | w2_straight (from partialJunctionY) | Regularized weighting factor for steady mass flow pressure (straight inlet) | |
| Real | w2_branching (from partialJunctionY) | Regularized weighting factor for steady mass flow pressure (branching inlet) | |
| Real[2] | w2 (from partialJunctionY) | {w2_straight, w2_branching} | Regularized weighting factor for steady mass flow pressure [straight branching] |
| SI.Pressure[2] | r_in (from partialJunctionY) | Inertal pressure inlet [straight branching] | |
| 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_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 |