modelDynamicJunctionN
Extends from ThermofluidStream.Utilities.DropOfCommonsPlus.
Information
Dynamic variant of the generic N-to-1 junction. This model includes dynamic pressure/momentum effects and is intended for transient simulations of merging nodes.
This junction model (see fig. 1) mixes fluids of different velocity entering the mixing chamber by different cross section areas and outputs the mixed fluid on an outlet with a separate area.
The pressure balance is done on the steady-state pressure, and mixing (red) assumes to preserve the kinetic energy of the fluid, resulting in an effective mixing velocity and area. This implies, that the mixing area A_mix changes during the simulation, which can be interpreted as narrowing down the mixing area by flow separation.
After mixing the fluid is accelerated to match the outlet area.
In general the component has two non-linear equation systems of size 1. This can be resolved by setting Advanced->assumeConstantDensity=true (default: false), simplifying several computations under the assumption of constant density of all fluid streams being mixed.
fig. 1
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | assumeConstantDensity | true | = true, if incompressibility is assumed (use '= false' for Ma > 0.3) |
| Integer | N | 1 | Number of inlets |
| SI.Area[N] | A | Cross section area of inlets | |
| SI.Area | A_out | Outlet cross section area | |
| Advanced | |||
| SI.MassFlowRate | m_flow_reg | dropOfCommons.m_flow_reg | Regularization threshold for small mass flows |
| Utilities.Units.Inertance | L | dropOfCommons.L | Inertance of each inlet/outlet |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Interfaces.Inlet[N] | inlets | Vector of N inlets | |
| Interfaces.Outlet | outlet | Outlet | |
| JunctionN | junction | ||
| Boundaries.DynamicPressureInflow | dynamicPressureInflow | ||
| Modelica.Blocks.Sources.RealExpression | v_mix | Conservation of kinetic energy |
Contents
| Name | Description |
|---|---|
| Medium | Medium model |