modelDynamicPressureInflow
Extends from Interfaces.SISOFlow.
Information
This inflow boundary is supposed to start an area of the model where dynamic pressure is taken into account. The area is ended with DynamicPressureOutflows.
Components that take dynamic pressure into account (marked with green symbols) should only be used in areas surrounded by DynamicPressureInflows and DynamicPressureOutflows.
The components input velocity can be set to a fixed value or given by a signal. From this reference inflow velocity the medium is accelerated to fit the outflow velocity, that is computed by the area of the component. The sign of the velocity is defined to match the sign of the mass-flow rate at the inlet.
The pressure difference resulting from the velocity difference is based on the total pressure balance, implicitly assuming a nozzle/diffusor of suitable area ratio. When the sign of the velocity does not match the sign of the mass-flow rate, this assumption cannot be upheld. The model then extrapolates the dynamic pressure difference in order to maintain a stable and well-natured behavior but its validity is lost.
The area can be set to a fixed value or given by a signal, representing a variable-area inlet.
By default, the density is assumed to be constant across the component and only the inlet density is used for the calculation of the velocity. This assumption can be reverted by setting assumeConstantDensity = false. This will lead to a non-linear equation system of size 1, as the outlet velocity is calculated based on the outlet density.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | assumeConstantDensity | true | = true, if incompressibility is assumed (use '= false' for Ma > 0.3) |
| Boolean | dv_in | displayParameters and not velocityFromInput and displayInletVelocity | Display inlet velocity |
| Boolean | displayA | displayParameters and displayOutletArea and not areaFromInput | Display outlet cross section area |
| String | compressibilityString | if assumeConstantDensity then "incompressible" else "compressible" | |
| String | displayPos1 | if displayCompressibilityApproach then compressibilityString elseif displayA then "A_out = %A_par" elseif displayInertance then "L = %L" else "" | |
| String | displayPos2 | if displayCompressibilityApproach and displayA then "A_out = %A_par" elseif displayInertance and not displayPos1 == "L = %L" then "L = %L" else "" | |
| String | displayPos3 | if displayCompressibilityApproach and displayA and displayInertance then "L = %L" else "" | |
| Nozzle / Diffusor definition | |||
| Boolean | velocityFromInput | false | = true, if input connector for outlet velocity is enabled |
| SI.Velocity | v_in_par | 0 | Inlet velocity |
| Boolean | areaFromInput | false | = true, if input connector for cross section area is enabled |
| SI.Area | A_par | 1 | Outlet cross-section area |
| Advanced › Regularization | |||
| Boolean | extrapolateQuadratic | false | = true, if extrapolating negative velocities purely quadratic |
| SI.MassFlowRate | m_flow_reg | dropOfCommons.m_flow_reg | Regularization threshold of mass flow rate |
| Layout › Display parameters | |||
| Boolean | displayCompressibilityApproach | true | = true, if assumeConstantDensity is displayed |
| Boolean | displayInletVelocity | true | = true, if inlet velocity v_in_par is displayed |
| Boolean | displayOutletArea | true | = true, if outlet cross section area A_par is displayed |
| Boolean | displayInertance | false | = true, if inertance L is displayed |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealInput | A_var | Outlet cross section area input connector [m2] | |
| Modelica.Blocks.Interfaces.RealInput | v_in_var | Inlet velocity input connector [m/s] |